investigations into petroleum source rocks within the
TRANSCRIPT
Investigations into Petroleum Source Rocks within the Mississippian Madison Group: Bluell
Subinterval of Western McKenzie CountyTimothy O. Nesheim1, Stephan H. Nordeng2, and Chioma J. Onwumelu2
1North Dakota Geological Survey2University of North Dakota
GEOLOGIC INVESTIGATION NO. 255NORTH DAKOTA GEOLOGICAL SURVEYEdward C. Murphy, State GeologistLynn D. Helms, Director Dept. of Mineral Resources2021
Table of Contents
Tables
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Stratigraphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Previous Work. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Core Geochemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Lower Bluell Subinterval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Lower Bluell core Lithofacies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Wireline Log Signataure and Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Interpretations and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Thermal Maturity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Kerogen Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Additional Madison Source Beds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-10
Table 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-18
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Figures
Figure 1. Map of western North Dakota showing the distribution of oil and gas productive Madison wells and the study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Figure 2. Stratigraphic column of the Mississippian Madison Group section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Figure 3. Study area map displaying the five study cores and structure contours of the Frobisher-Alida Interval top in feet below sea level. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Figure 4. Wireline log cross-section of the lower Ratcliffe and upper Frobisher-alida subintervals with TOC-RockEval core data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Figure 5. Organic-richness plot of Madison core samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Figure 6. Modified Van Krevelen diagram with brown circles depicting samples from the lower Bluell subinterval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Figure 7. Tmax versus measured depth of Madison core samples color coated based upon NDIC well number and symbol shaped based upon Bluell versus non-Bluell subinterval . . . . . . . . . . . . . . . 6Figure 8. Core photographs from the lower Bluell subinterval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Figure 9. Isopach map of the gross thickness of the high TOC lower Bluell facies . . . . . . . . . . . . . . . . . . . . . . . . . 8
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INTRODUCTIONMississippian Madison Group (Madison) reservoirs have combined to produce over 1 billion barrels of oil to date from over 6,000 vertical and horizontal wells within the Williston Basin of North Dakota (Fig. 1) (NDOGD, 2019). Cumulative production from the Madison is second only in the state to the prolific Bakken-Three Forks play. Prior to the emergence of the Bakken-Three Forks play (~2006), Madison reservoirs served as the primary target for hydrocarbon production in the state and accounted for approximately 64% of the state’s oil production through the end of 2005 (NDOGD, 2019).
Madison production began shortly after the discovery of oil in North Dakota during the early 1950’s. Through the 1980’s, exploration and development of the unit was completed using primarily vertical wells (LeFe-ver, 1992). Horizontal well drilling (non-hydraulically fractured) emerged in the Madison beginning in the late 1980’s to early 1990’s (LeFever, 1992). More re-cently, the Midale-upper Rival play of northern Burke County has transitioned into the first in-state Madison play undergoing unconventional-style development, horizontal drilling coupled with multi-stage hydraulic fracturing, and may hold potential for the drilling and completion of several hundred horizontal wells (Ne-sheim, 2018; 2019). The Midale-upper Rival play may represent the beginning of a transition of the greater Madison play into an unconventional, resource play that centers around targeting oil accumulations within tight, low porosity-permeability reservoirs.
Identifying and characterizing the petroleum source beds that have charged Madison reservoirs may serve as a key step in furthering exploration and develop-ment in the unit. Initial geochemical studies of pro-
duced oil and core extracts concluded that the Madison reservoirs were sourced by hydrocarbons generated and expelled by the underlying Bakken Formation (Dow, 1974; Williams, 1974; Thode, 1981; Leenheer and Zumberge, 1987). However, continued oil geochemical studies found that while some inter-mixing with Bakken oils occurs proximal to faulting/fracturing, Madison reservoir oils are distinct of Bakken oil and therefore, the Madison likely contains one or more organic-rich source bed horizon(s) (Price and LeFever, 1992; Osadetz and Snowden, 1995; Jarvie, 2001; Jiang et al., 2001). Organic-rich horizons have been described within the Mission Canyon and Lodge-pole Formations, which comprise the middle and lower portions of the Madison (Osadetz and Snowdon, 1995; Jar-vie, 2001; Jiang et al., 2001; Chen et al., 2009). However, limited information exists regarding the stratigraphic and vertical extent, organic-richness, and thermal maturity of prospective petroleum source beds within the Madison section. Therefore, the purpose of this report is to review TOC-RockEval analysis data from select Madison cores, in combination with wireline logs, to identify and evaluate prospective Madison source bed horizons.
STRATIGRAPHYThe Madison is predominantly a carbonate-evaporite unit that is subdivided into the Lodgepole, Mission Canyon, and Charles Formations in ascending order within the North Dakota portion of the Williston Basin (Fig. 2) (Murphy et al., 2009). The Mission Canyon and Charles Formations are further subdivided into the Tilston, Frobisher-Alida, Ratcliffe, and Poplar Intervals, from which the Frobisher-Alida and Ratcliffe Intervals contain the majority of oil producing reservoirs in the Madison section (Fig. 2) (LeFever and Anderson, 1986: Murphy et al., 2009).
The Frobisher-Alida Interval has been described as an upward-shoaling cycle which began with open-marine sedi-mentation that transitioned into widespread sabkha-saline evaporites (Petty, 1988). The Frobisher-Alida has been
Figure 1. Map of western North Dakota showing the distribution of oil and gas productive Madison wells (black dots) and the study area. County lines are shown as light gray lines.
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subdivided into upwards of seven subintervals, which listed in ascending order consist of the Landa, Wayne, Glenburn, Mohall, Sherwood, Bluell, and Rival subintervals (Fig. 2) (LeFever and Anderson, 1986; Petty, 1996). The subintervals are defined by widespread marker beds, generally range from 30 to 100 feet (10 to 30 meters) in thickness and vary between different aggradation/progradation styles (Petty, 1996).
PREVIOUS WORKUsing early geochemical analysis techniques on both produced and core extract oil sam-ples, Williams (1974) concluded that Madison reservoir oils comprised of a unique oil family that was sourced from organic-rich shales in the underlying Bakken Formation (Fig. 2). Vertical oil migration from the Bakken shales to the overlying Madison reservoirs was hypothesized to have occurred along faulting/fracturing trends such as the Nesson anticline with lateral migration through intraformational porous and permeable carrier beds (Dow, 1974). Initial subsequent studies further examining both produced and core extract oil samples yielded similar interpretations about the Madison-Bakken Petroleum System (Thode, 1981; Leenheer and Zumberge, 1987).
However, as oil geochemistry studies continued in the Williston Basin, Bakken and Mad-ison oils have been found to be notably distinct from one another. Price and LeFever (1992) observed that Madison oils are more paraffinic and display higher gas chromato-gram peaks in the n-C20 to n-C30 range than Bakken oils, which conversely are less par-affinic and display higher gas chromatogram peaks in the n-C10 to n-C17 range. Fur-thermore, Madison reservoir oils are distinct from Bakken oils across the US Williston Basin based upon light hydrocarbon and C8+ fingerprints (Jarvie, 2001). Madison oils are commonly noted to have a C35 hopane predominance, which is limited to absent within Bakken oils (Osadetz and Snowden, 1995; Jarvie, 2001). Also, Madison reservoir oils have also been found to differentiate from Bakken oils in North Dakota and Montana based upon pristane-phytane ratios, where Madison oils have overall lower pristane-phytane ratios (Price and LeFever 1992; Jarvie, 2001). Similarly, oil extracts from Bakken shale core samples consistently have higher reported pristane-phytane ratios than oil extracts from organic-rich lime mudstone core samples from the Lodgepole Formation in southern Saskatchewan (Osadetz et al., 1992; Jiang et al. 2001). The organic-rich lime mudstone extracts also displayed a C35 hopane predominance and other factors that are indicative of a Lodgepole source for a portion of Madison reservoir oils (Osadetz et al., 1992; Jiang et al. 2001). Thus, while early geochemistry studies linked Madison reservoir oils to the Bakken shale, continued investigations have differentiated Madison and Bakken oils with some indications of the Madison source originating in the Lodgepole Formation.
Madison source beds may be comprised of differing kerogen type(s) dependent on stratigraphic positioning. Jarvie (2001) inferred two sets of Madison source beds using the methodology from Hughes et al. (1995): 1) carbonate source beds with higher sulfur content that have charged Madison reservoirs along the North Dakota-Montana northern tier counties, and 2) marly shale facies with lower sulfur contents that have sourced reservoirs within the central basin. The higher sulfur, carbonate-sourced oils were described to have lower API oil gravity and in-terpreted to have been generated at lower thermal maturity while the lower sulfur, marly shale-sourced oils have higher API oil gravities and are believed to be generated at higher thermal maturities (Jarvie, 2001). Lillis (2012) noted that most oils produced from reservoirs in the Frobisher-Alida Interval have high sulfur content, indicative of Type II-S kerogen which thermally matures at lower temperatures compared to Type I and regular Type II kero-gen. Meanwhile, oils produced from reservoirs in the Ratcliffe Interval (includes Midale), upper Rival subinterval (Nesson), Landa subinterval (basal Frobisher-Alida), and Tilston Interval were noted to contain mostly moderate to low sulfur concentrations, indicative of non-Type II-S kerogen (Lillis, 2012). Furthermore, Jarvie (2016) noted that Madison source rocks display variability in organofacies based upon light hydrocarbons and biomarker data from samples spanning the Ratcliffe, Frobisher-Alida, and Tilston Intervals. In summary, previous studies indicate that
Figure 2. Stratigraphic col-umn of the Mississippian Madison Group section. The dark blue portion rep-resents the section exam-ined in this report. Dev. = Devonian; Fm. = Forma-tion; Mbr. = Member; un-diff. = undifferentiated
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Madison oils from differing stratigraphic intervals are from multiple source bed horizons with variable organofa-cies that range from Type II to Type II-S kerogen.
While the Madison appears to have one or more distinct sets of petroleum source beds based upon oil geochem-ical analysis data, there are areas in the basin which exhibit varying degrees of mixing between Madison and non-Madison sourced oils. Madison reservoir oils from the Richey and Cow Creek Fields of eastern Montana show evidence of mixing between Red River and Madison sourced oils (Jarvie, 2001). Furthermore, Madison reservoir oils from the Poplar Dome area of eastern Montana, as well as the McGregor and Beaver Lodge Fields located along the Nesson anticline of western North Dakota, display a mixed Bakken-Madison sourced signature (Jarvie, 2001: Jiang and Li, 2002). Both the Poplar Dome and Nesson anticline are prominent structural features within the basin where faults may have served as conduits for vertical oil migration (Orchard, 1987). Also, Bakken oil has sourced the Lodgepole mounds near Dickinson, North Dakota, localized reservoir features positioned in the basal Lodgepole Formation that directly overly the Bakken Formation (Jiang et al., 2002a). From the Canadian portion of the Williston Basin, Madison reservoir oils from fields located along regional inferred faulting-fracture trends exhibit geochemical signatures indicative of mixed Bakken and Madison derived oils (Jiang and Li, 2002; Chen et al., 2009). Therefore, some evidence remains of non-Madison sourced oils migrating into Madison reservoirs, par-ticularly along structures that exhibit substantial vertical faulting/fracturing.
Initial studies reported TOC values in the Madison Group consistently <1% (Williams, 1974; Osadetz and Snowdon, 1986). However, Osadetz et al. (1992) and Osadetz and Snowdon (1995) later published datasets (3 and 23 sam-ples) in which organic-rich Lodgepole samples from southern Saskatchewan averaged TOC values of 4.84% and 5.49% with corresponding average HI values of 594 and 401 mg HC/g TOC. Jiang et al. (2001) reported additional data from organic-rich Lodgepole lime mudstone samples (10 samples from 5 cores), also from southern Saskatch-ewan, that similarly averaged 5.3% TOC (2.1-10.3%) with an average hydrogen index of 591 mg HC/g TOC. Further-more, Jarvie (2001) reported three organic-rich horizons in the Mission Canyon Formation in one core from eastern Montana that averaged TOC values of 1.96%, 8.50%, and 1.92% with corresponding HI average values of 394, 300, and 274 mg HC/g. More recently, Jarvie (2016) reported that elevated TOC values (>1% present-day values) are present in multiple Madison subintervals spanning the Ratcliffe, Frobisher-Alida, and Tilston Intervals. While previous studies have differentiated Madison reservoir oils from Bakken oils over large portions of the Willis-ton Basin, limited published information exists on the stratigraphic positioning, lateral extent, and organic richness of petroleum source beds in the Madison.
METHODSFive Madison cores were selected for examination and sampling that extend through the upper portions of the Frobisher-Alida Interval in western McKenzie Coun-ty (Figs. 3 and 4). In addition to stratigraphic position-ing, each core was further selected based upon one or more of the following criteria: 1) previously completed
Figure 3. Study area map displaying the five study cores (col-ored-coded circles to match figure 7) and structure contours on the Frobisher-Alida Interval top in feet below sea level (grey lines). Small grey dots depict wireline log control wells for the structure contours. NDIC (North Dakota Industrial Commis-sion) well numbers are listed above each core location symbol with average reliable Tmax values from the Bluell subinterval below (Tmax value ranges underneath). Study area is depicted on the Figure 1 regional map. Red lines depict documented structures: a = Mondak monocline, b = Beaver Creek anticline, c = Red Wing Creek structure, d = Little Knife anticline
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TOC-RockEval data indicative of organic-rich and oil-prone source rock (≥1-2% TOC, S2 versus S3 ratios of ≥3), 2) elevated core-plug oil saturations (≥40-60% So) within low-porosity core sections (≤2-3% ɸ), 3) darkly colored in-tervals observed through available core photographs, and/or 4) cores located within previously sampled/identified stratigraphic sections that yielded organic-rich samples.
Each core was examined, described, and correlated to corresponding wireline logs before being sampled. Geologic tops from the lower Ratcliffe (Midale subinterval) and upper Frobisher-Alida (Rival, Bluell, Sherwood, and Glenburn subintervals) Intervals were extracted from Petty (1988; 1996) and McClellan (1995) and subsequently correlated into and across the study area using wireline logs from available wells including the five cored wells of the study (Fig. 4).
TOC-RockEval samples were collected using a drill press that allowed for pinpoint sampling precision while creating a fine, powdered sample adequate for analysis while preserving the integrity of sampled cores. Samples collected from NDIC (North Dakota Industrial Commission) well permit #7228 are approximate 1-foot averages while the other four cores were sampled at specific depth points. Samples from all five cores represent both the darker colored and adjacent lighter colored core intervals. Sample analysis for TOC-RockEval data was completed using the Source Rock Analyzer available through the University of North Dakota.
The organic richness of the analyzed samples was evaluated through the combination of TOC and HI data. TOC values of 1% by weight or greater are generally considered good quality source rock (Peters and Cassa, 1994). Therefore, a 1% TOC threshold was used as a general cutoff to identify prospective, organic-rich, petroleum source rock horizons. HI is a measurement of milligrams of hydrocarbons (mg HC) per gram of total organic carbon (TOC) generated and measured during Rock-Eval pyrolysis. HI essentially represents the ratio of kerogen (organic carbon capable of converting to hydrocarbons) to that of TOC on a scale of 0–1200. HI and TOC both gradually decrease during thermal maturation of a given source rock as kerogen (oil-prone organic carbon) is converted into hydrocarbons and generated hydrocarbons are expelled from the source rock (Dembicki, 2009).
Thermal maturity was evaluated using Tmax generated from the RockEval Pyrolysis analyzes. Increased Tmax values indicate higher levels thermally maturity for sample with respect to hydrocarbon generation and the greater the percentage of original kerogen that has been converted into hydrocarbons (Peters, 1986). Pyrogram curves were visually examined to evaluate the S2 peaks used to determine the Tmax values. Tmax values were also plotted against PI values to determine if there were any notable variances between increasing PI with respect to changes to Tmax.
Core to log (wireline logs) adjustments were made comparing described core lithologies, core gamma-ray, and core-plug porosity data to corresponding wireline logs. The wireline-log signatures through organic-rich horizons identified through TOC-RockEval analysis (generally containing ≥1% TOC) were examined and utilized to correlate the horizons between non-cored and/or non-sampled wells.
RESULTSCORE GEOCHEMISTRYA total of 222 core samples were collected and analyzed for TOC-RockEval data. TOC values ranged from 0.21 to 17.02 % by weight with an average of 1.1% (Fig. 5, Table 1). While elevated TOC values (≥1%) were found intermittently throughout the various subintervals comprising lower Ratcliffe and upper Frobisher-Alida Intervals, the majority of higher TOC values of 1% or greater were from the lower half of the Bluell subinterval (lower Bluell) (Fig. 5). Examining HI versus OI, the composite Madison samples plot along a Type I/II to Type III/IV kerogen signatures on a modified Van Krevelen diagram, with higher TOC samples preferentially plotting more towards a Type I/II, oil-prone kerogen signature (Fig. 6).
Including the entire Madison dataset generated from all five cores, a total of 70 reliable Tmax values were identified based upon pyrogram S2 peaks and PI values. Out of those Tmax values, 46 were from the Bluell subinterval, which
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Figure 6. Modified Van Krevelen diagram with brown circles depicting samples from the lower Bluell subinterval: small and light brown circles = <1% TOC, medium sized and colored = 1-2% TOC, large and dark brown = >2% TOC. Small white squares rep-resent non-lower Bluell Madison samples.
Figure 7. Tmax versus measured depth (below surface) of Madison core samples color coated based upon NDIC well number and sym-bol shaped based upon Bluell versus non-Bluell subinterval.
Figure 5. Organic-richness plot of Madison core samples. Brown cir-cles depict samples from the lower Bluell subinterval with size and color shading based upon cutoffs for good (>1%) and excellent (>2%) quality source rock (Dembicki, 2009). Small and light brown circles = <1% TOC, medium sized and colored = 1-2% TOC, large and dark brown = >2% TOC. Small white squares represent non-lower Bluell Madison samples.
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ranged from 437.0 to 456.0 °C and averaged 446.8 °C (Table 1). Overall, the Bluell and other Madison Tmax values increase with depth but with a non-linear relationship that varies from one core data set to another (Fig. 7). Spatially, the Bluell Tmax values increase east-southeast across the study area (Fig. 3).
LOWER BLUELL SUBINTERVALSamples with ≥1% TOC in the lower Bluell vertically span upwards of approximately 15 to 20 feet in gross thickness within three of the study cores located in the central to western portions of the study area (Figs. 3 and 4 – wells #6414, #7228, and #6747). In those cores, the lower Bluell averages approximately 1-2% TOC, but with highly variable organic-richness in which individual sample TOC and HI values range from upwards of 6% and ≥200 mg HC/g TOC down to <0.5% and ≤50 mg HC/g TOC (Figs. 4-6). In the northern most study core (Figs. 3 and 4 - well #6839), a few of the lower Bluell samples contained ~1% TOC with higher HI (100-200 mg HC/g TOC), but most of the samples of the subinterval were relatively organic-lean with either <1% TOC and/or low HI (<100 mg HC/g TOC). The fifth and eastern most core (Figs. 3 and 4 - well #6718) was not sampled for TOC-RockEval analysis due to the lithological makeup of the lower Bluell which is reviewed below.
LOWER BLUELL CORE LITHOFACIESIn conjuncture with sampling for TOC-RockEval analysis, each study core was logged (described) and correlated to wireline logs for preliminary, regional stratigraphic correlations. Examining the lithological trends of the five study cores, the lower Bluell is primarily comprised of medium brown to very dark grey fossil lime wackestone within the four more westerly cores in the study area (Fig. 8A and 8B, Plate I). The higher TOC values (≥1%) correspond-ed with dark to very dark grey/black, moderately to well laminated, fossil lime wackestone containing relatively abundant brachiopod shells and crinoid stem fragments (Fig. 8A, Plate I). Meanwhile, the lower TOC values (<1%) corresponded with medium brown, poorly laminated, fossil lime wackestone to floatstone, in which tabulate and/or rugose corals where present in addition to brachiopod and crinoids (Fig. 8B, Plate I). In the fifth and eastern most core examined, the lower Bluell consists primarily of light to medium brown, oolitic-peloidal lime grainstone (Fig. 8C, Plate I), a high energy carbonate facies.
WIRELINE LOG SIGNATURE AND MAPPINGUnlike typical organic-rich petroleum source beds, such as the Upper and Lower Bakken shales, the higher TOC (≥1%) facies of the Bluell cannot readily be differentiated from the lateral or vertically adjacent, lower TOC (<1%)
Figure 8. Core photographs from the lower Bluell subinterval. A) Dark grey to black, laminated, fossil lime wacke-stone, B) medium brown to dark grey, poorly laminated, fossil lime wackstone, and c) medium tan/brown, laminated, oolitic-peloidal lime grainstone. NDIC (North Dakota Industrial Commission) well number and core depth interval in the bottom left corners and one-inch scale bars in the bottom right corners of each photograph.
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strata using the gamma-ray wireline log signature. Instead, the high TOC Bluell facies has to be identified on wire-line logs using cross-plots of deep resistivity versus sonic travel time, neutron porosity, and bulk density logs (Fig. 4 – cross-section) (Passey et al., 1990). The high TOC Bluell facies appears to correspond with where all three cross-plots display a positive deep resistivity cross-over in which deep resistivity values are above 200 ohmmeters (Fig. 4).
The lower Bluell high TOC facies was first correlated across the study area starting with the core-control wells and their corresponding digitized logs followed by additional available digital wireline logs. Next, raster logs were used to further correlate the lower Bluell high TOC facies. While the raster logs did not allow for wireline log cross-plots, a combination of gamma-ray and resistivity wireline logs along with neutron-density porosities and/or sonic travel time appear adequate for correlation when compared to the digital logs of previously correlated wells.
Overall, the high TOC facies of the lower Bluell ranged from being absent, particularly towards the east-southeast parts of the study area, to reaching gross thicknesses of upwards of 30 ft. towards the northwest, and generally ranges from 10 to 20 ft. thick when present (Fig. 9). As the high TOC facies of the lower Bluell thins and disap-pears in the subsurface, the thickness of the Bluell interval does not appear to substantially thin or thicken (Fig. 4). Instead, based on both log and core data, the high TOC facies of the lower Bluell laterally grades into either organic-lean fossil lime wackestone or oolitic-peloidal lime grainstone. Also, the gross-thickness of the high TOC Bluell facies decreases to becomes absent proximal to structures, which mostly trend northwest-southeast across the study area (Fig. 9). INTERPRETATIONS AND DISCUSSIONTHERMAL MATURITYTmax values indicate that the high TOC facies of the lower Bluell has reached the early to late stages of oil genera-tion within the study area. The early, peak, and late oil generation windows are typically represented by Tmax val-ue ranges of 435-445 °C, 445-450 °C, and 450-470 °C (Peters and Cassa, 1994). The individual reliable Bluell Tmax values ranged from 437 °C to 456 °C, while the core data set averages ranged from 441°C to 453 °C (Fig. 7, Table 1), indicative that the Bluell is within the early to late oil generation windows. However, as previously noted, oils produced from the Frobisher-Alida reservoirs are commonly en-riched in sulfur, which is indicative of Type II-S ker-ogen that thermally matures at lower temperatures (Lillis, 2012). Jarvie (2016) assumed a Tmax of 427 °C to mark the beginning of the oil generation win-dow for Madison source bed samples. Therefore, the lower Bluell may be within the peak to late oil generation window dependent upon the type(s) of kerogen present.
Figure 9. Isopach map of the gross thickness of the high TOC lower Bluell facies. Contours are in 5-foot intervals and the brown contour fill is in 10-foot intervals. Small light grey circles are the wireline log well control and the large black circles are the core control wells. Study area is depicted on the Figure 1 regional map. Red lines depict documented structures: a = Mondak monocline, b = Beaver Creek anticline, c = Red Wing Creek structure, d = Little Knife anticline
9
KEROGEN TYPERegarding kerogen type(s) within prospective Madison source beds, a few general comments/conclusions can be drawn. First, if the lower Bluell and adjacent strata are within the peak to late mature stages of the oil generation window, the majority (≥50%) of the original kerogen has likely been converted into hydrocarbons and the current kerogen signature based on HI versus OI ratios is not fully reflective of the original kerogen signature (Dembicki, 2009). Secondly, Frobisher-Alida reservoirs are primarily known to produce oil with gas as a secondary component. This means any substantial prominence of Type III gas-prone kerogen within Madison source beds is unlikely, and therefore the original kerogen was likely oil-prone Type I, Type II, and/or Type II-S.
ADDITIONAL MADISON SOURCE BEDSWhile this report focused on the Bluell because of the prominence of elevated TOC values, core samples with elevated TOC, coupled with increased HI, extended stratigraphically well beyond the Bluell. Furthermore, wireline log cross-plots of deep resistivity versus bulk density, neutron porosity, and sonic velocity in numerous wells examined indicate additional prospective organic-rich horizons of various thicknesses and lateral distributions that are present in both subintervals above and below the Bluell.
CONCLUDING REMARKS• The Bluell subinterval, particularly the lower Bluell, contains the most prominent vertical and lateral
distribution of high TOC values (≥1%) within the sampled cores spanning the upper Frobisher-Alida and lower Ratcliffe intervals.
• Wireline log cross-plots of deep resistivity versus bulk density, neutron porosity, and sonic travel time are useful when combined to identify prospective organic-rich carbonate rock within the Madison Group.
• Core data, combined with wireline log cross-plot mapping, demonstrates the lower Bluell is comprised of upwards 20-30 ft. (gross thickness) of organic-rich carbonate rock along western McKenzie County.
• Tmax values indicate that the lower Bluell within western McKenzie County and any stratigraphically adjacent Madison petroleum source beds range from the early to late, or peak to late mature stages of oil generation depending upon the type(s) of kerogen present.
REFERENCESChen, Z., Osadetz, K.G., Jiang, C., and Li, M., 2009, Spatial variation of Bakken or Lodgepole oil in the Canadian Williston Basin:
American Association of Petroleum Geologists Bulletin, v. 93, p. 829-851.Dembicki, H., 2009, Three common source rock evaluation errors made by geologists during prospect or play appraisals: American
Association of Petroleum Geologists Bulletin, v. 93, p 341-356.Dow, W. G., 1974, Application of oil-correlation and source-rock data to exploration in Williston Basin: American Association of
Petroleum Geologists Bulletin, v. 58, p. 1253-1262.Hughes, W.B., Holba, A.G., and Dzou, L.I., 1995, The ratios of dibenzothiophene and pristane to phytane as indicators of depositional
environment and lithology of Petroleum source: Geochimica et Cosmochimica Acta., vol. 59, no. 17, 3581-3598.Jarvie, D.M., 2001, Williston Basin Petroleum Systems: Inferences from oil geochemistry and geology: The Mountain Geologist, vol.
38, no. 1, p. 19-41.Jarvie, D.M., 2016, Madison Group source rocks, Williston Basin, USA: American Association of Petroleum Geologists Annual
Convention and Exhibit, Calgary, Oral Presentation PowerPoint, 22 slides.Jiang, C., Li, M., Osadetz, K.G., Snowdon, L.R., Obermajer, M., Fowler, M.G., 2001, Bakken/Madison petroleum systems in the
Canadian Williston Basin. Part 2: molecular markers diagnostic of Bakken and Lodgepole source rocks: Organic Geochemistry, vol. 32, p. 1037-1054.
Jiang, C., and Li, M., 2002, Bakken/Madison petroleum systems in the Canadian Williston Basin. Part 3: geochemical evidence for significant Bakken-derived oil in Madison Group reservoirs: in Organic Geochemistry, vol. 33, p. 761-787.
Leenheer, M. J., and Zumberge, J. E., 1987, Correlation and thermal maturity of Williston Basin crude oils and Bakken source rocks using Terpane Biomarkers: in Williston Basin: Anatomy of a Cratonic Oil Province, p. 287-298.
LeFever, J.A, and Anderson, S.B., 1986, Structure and stratigraphy of the Frobisher-Alida and Ratcliffe Intervals, Mississippian Madison Group, north-central North Dakota: North Dakota Geological Survey, Report of Investigation No. 84, 17 pp. and 14 pl.
LeFever, J.A., 1992, Horizontal drilling in the Williston Basin, United States and Canada: Rocky Mountain Association of Geologists, Geological Studies Relevant to Horizontal Drilling: Examples from Western North Dakota; edited by J.W. Schmoker, E.B. Coalson, and C.A. Brown, p. 177-197.
Lillis, P. G., 2012, Review of oil families and their petroleum systems of the Williston Basin: The Mountain Geologist, vol. 50, no. 1, p. 5-31.
McClellan, W. A., 1995, Sherwood subinterval of the Mission Canyon Formation in central western North Dakota, North Dakota Geological Survey, Report of Investigation No. 97, 11 pp. and 7 pl.
Murphy, E.C., Nordeng, S.H., Junker, B.J., and Hoganson, J.W., 2009, North Dakota stratigraphic column: North Dakota Geological Survey Miscellaneous Series 91.
Nesheim, T.O., 2018, Spatial distribution of elevated oil saturations within the Midale subinterval (Mississippian Madison Group), Burke County – North Dakota: North Dakota Geological Survey, Geological Investigation No. 213, 18 p.
Nesheim, T.O., 2019, Review of the emerging Midale-upper Rival (Mississippian Madison Group) unconventional-style play, northern Burke County: North Dakota Department of Mineral Resource, Geo News, vol. 46, no. 1, p. 4-6.
North Dakota Oil and Gas Division (NDOGD), 2019, North Dakota cumulative oil production by formation through December 2019: https://www.dmr.nd.gov/oilgas/stats/2019CumulativeFormation.pdf (retrieved September 30th, 2020).
Thode, H.G., 1981, Sulphur isotope ratios in petroleum research and exploration: Williston Basin: in American Association of Petroleum Geologists Bulletin, vol. 65, p. 1527-1535.
Orchard, D. M., 1987, Structural history of Poplar Dome and the Dissolution of Charles Formation salt, Roosevelt County, Montana: in C.G. Carlson and J.E. Christopher eds., 1987, Fifth International Williston Basin Symposium, Saskatchewan Geological Society, p. 169-177.
Osadetz, K.G., Brooks, P.W., and Snowdon, L.R., 1992, Oil families and their sources in Canadian Williston Basin, (southeastern Saskatchewan and southwestern Manitoba): Bulletin of Canadian Petroleum Geology, vol. 40, no. 2, p. 254-273.
Osadetz, K.G., and Snowdon, L.R., 1986, Petroleum source rock reconnaissance of southern Saskatchewan: in Current Research, Pat A, Geological Survey of Canada, Paper 86-1A, p. 609-617.
Osadetz, K.G., and Snowdon, L.R., 1995, Significant Paleozoic petroleum source rocks in the Canadian Williston Basin: Their distribution, richness, and thermal maturity (southeastern Saskatchewan and southwestern Manitoba): Geological Survey of Canada, Bulletin 487, 60 p.
Passey, Q. R., Creaney, S., Kulla, J. B., Moretti, F. J., Stroud, J. D., 1990, A practical model for organic richness from porosity and resistivity logs: American Association of Petroleum Geologists Bulletin, vol. 74, p. 1777-1794.
Peters, K.E., 1986. Guidelines for evaluating petroleum source rock using programmed pyrolysis. AAPG (Am. Assoc. Pet. Geol.) Bull. 70 (3), 318–329.
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Price, L.C., and LeFever, J.A., 1992, Does Bakken horizontal drilling imply a huge oil-resource base in fractured shales?, in LeFever, J.A., eds., Geological Studies Relevant to Horizontal Drilling: Examples from Western North America: Rocky Mountain Association of Geologists, Denver, CO, p. 199-214.
Williams, J. A., 1974, Characterization of oil types in Williston Basin: American Association of Petroleum Geologists Bulletin: v. 58, p. 1243-1252.
10
11
SRA
Tmax
Tmax
Calc
.S1
/TO
CM
adis
onTo
pBa
seTO
C(°
C)Q
ualit
y%
Ro
*100
Subu
nit
6414
3305
3007
3900
0092
921.
630.
962.
160.
3844
41
0.83
133
235.
759
0.31
R (u
n)64
1433
0530
0739
0000
9293
.80.
910.
330.
810.
2544
51
0.84
8927
3.2
360.
29R
(un)
6414
3305
3007
3900
0092
951.
220.
481.
920.
3044
21
0.80
157
256.
439
0.20
R (u
n)64
1433
0530
0739
0000
9296
0.95
0.18
0.37
0.53
440
30.
7739
560.
719
0.33
R (u
n)64
1433
0530
0739
0000
9305
1.06
0.22
0.38
0.50
439
30.
7436
470.
821
0.37
R (u
n)64
1433
0530
0739
0000
9310
.85
0.85
0.84
0.75
0.40
438
30.
7288
471.
999
0.53
R (u
n)64
1433
0530
0739
0000
9311
.80.
540.
250.
310.
2544
43
0.83
5746
1.2
460.
45R
(un)
6414
3305
3007
3900
0094
010.
620.
860.
610.
4044
13
0.77
9865
1.5
139
0.59
FA (B
l)64
1433
0530
0739
0000
9402
1.18
1.19
1.16
0.48
441
20.
7898
412.
410
10.
51FA
(Bl)
6414
3305
3007
3900
0094
031.
050.
630.
840.
3344
73
0.88
8031
2.5
600.
43FA
(Bl)
6414
3305
3007
3900
0094
040.
660.
410.
400.
3244
23
0.79
6148
1.3
620.
51FA
(Bl)
6414
3305
3007
3900
0094
050.
330.
120.
130.
2943
33
0.64
3988
0.4
360.
48FA
(Bl)
6414
3305
3007
3900
0094
160.
691.
630.
720.
3743
83
0.72
104
541.
923
60.
69FA
(Bl)
6414
3305
3007
3900
0094
171.
680.
661.
080.
4443
73
0.71
6426
2.5
390.
38FA
(Bl)
6414
3305
3007
3900
0094
181.
940.
701.
250.
4643
93
0.75
6424
2.7
360.
36FA
(Bl)
6414
3305
3007
3900
0094
191.
000.
561.
050.
3044
72
0.89
105
303.
556
0.35
FA (B
l)64
1433
0530
0739
0000
9420
0.87
0.59
0.80
0.31
448
20.
9092
362.
668
0.42
FA (B
l)64
1433
0530
0739
0000
9421
1.18
0.34
0.83
0.38
448
20.
9070
322.
229
0.29
FA (B
l)64
1433
0530
0739
0000
9422
.20.
700.
200.
250.
3544
83
0.91
3650
0.7
290.
44FA
(Bl)
6414
3305
3007
3900
0094
230.
870.
400.
490.
3344
62
0.86
5638
1.5
460.
45FA
(Bl)
6414
3305
3007
3900
0094
241.
040.
530.
860.
2945
12
0.96
8328
3.0
510.
38FA
(Bl)
6414
3305
3007
3900
0094
251.
450.
302.
070.
3144
82
0.91
143
216.
721
0.13
FA (B
l)64
1433
0530
0739
0000
9426
0.65
0.24
0.33
0.32
450
30.
9451
491.
037
0.42
FA (B
l)64
1433
0530
0739
0000
9427
.20.
850.
160.
700.
3044
31
0.82
8235
2.3
190.
19FA
(Bl)
6414
3305
3007
3900
0094
281.
070.
650.
940.
3545
33
0.99
8833
2.7
610.
41FA
(Bl)
6414
3305
3007
3900
0094
291.
010.
251.
040.
3344
61
0.86
103
333.
225
0.19
FA (B
l)64
1433
0530
0739
0000
9430
.21.
190.
491.
120.
4144
61
0.88
9434
2.7
410.
30FA
(Bl)
6414
3305
3007
3900
0094
310.
800.
370.
560.
3444
42
0.83
7043
1.6
460.
40FA
(Bl)
6414
3305
3007
3900
0094
321.
220.
431.
360.
3544
31
0.82
111
293.
935
0.24
FA (B
l)64
1433
0530
0739
0000
9433
0.56
0.28
0.30
0.33
447
30.
8954
590.
950
0.48
FA (B
l)64
1433
0530
0739
0000
9434
0.43
0.22
0.20
0.27
443
50.
8147
630.
751
0.52
FA (B
l)64
1433
0530
0739
0000
9435
0.95
0.24
0.63
0.29
448
10.
9166
312.
225
0.28
FA (B
l)
S2/S
3PI
S1S2
S3HI
OI
Core
Dep
th (f
t.)N
DIC
#AP
I Num
ber
Tabl
e 1
12
SRA
Tmax
Tmax
Calc
.S1
/TO
CM
adis
onTo
pBa
seTO
C(°
C)Q
ualit
y%
Ro
*100
Subu
nit
6414
3305
3007
3900
0094
361.
650.
451.
840.
3144
61
0.87
112
195.
927
0.20
FA (B
l)64
1433
0530
0739
0000
9437
0.56
0.30
0.25
0.28
452
30.
9745
500.
954
0.55
FA (B
l)67
1833
0530
0824
0000
9416
.82.
061.
182.
500.
4944
82
0.91
121
245.
157
0.32
FA (R
i)67
1833
0530
0824
0000
9429
3.25
0.89
5.89
0.37
453
21.
0018
111
15.9
270.
13FA
(Bl)
6718
3305
3008
2400
0094
303.
641.
317.
650.
3645
32
0.99
210
1021
.336
0.15
FA (B
l)67
1833
0530
0824
0000
9431
2.94
0.94
4.75
0.41
451
20.
9616
214
11.6
320.
17FA
(Bl)
6718
3305
3008
2400
0094
3217
.02
6.70
38.0
10.
7245
62
1.04
223
452
.839
0.15
FA (B
l)67
1833
0530
0824
0000
9433
0.60
0.15
0.18
0.33
441
30.
7830
550.
525
0.45
FA (B
l)67
1833
0530
0824
0000
9466
1.31
0.54
0.90
0.51
446
30.
8769
391.
841
0.38
FA (S
h)67
1833
0530
0824
0000
9467
.20.
540.
200.
280.
2444
83
0.90
5244
1.2
370.
42FA
(Sh)
6718
3305
3008
2400
0094
74.2
0.48
0.09
0.13
0.35
451
30.
9527
730.
419
0.41
FA (S
h)67
1833
0530
0824
0000
9475
.50.
880.
310.
480.
3044
73
0.89
5534
1.6
350.
39FA
(Sh)
6718
3305
3008
2400
0094
76.1
0.74
0.34
0.47
0.29
446
30.
8664
391.
646
0.42
FA (S
h)67
1833
0530
0824
0000
9479
.40.
330.
190.
230.
2445
73
1.06
7073
1.0
580.
45FA
(Sh)
6718
3305
3008
2400
0094
80.8
50.
990.
440.
670.
3445
23
0.97
6834
2.0
440.
40FA
(Sh)
6718
3305
3008
2400
0094
82.2
0.89
0.29
0.44
0.31
451
20.
9649
351.
433
0.40
FA (S
h)67
1833
0530
0824
0000
9482
.80.
920.
290.
480.
1645
62
1.05
5217
3.0
320.
38FA
(Sh)
6718
3305
3008
2400
0094
86.6
0.61
0.16
0.19
0.23
464
51.
1931
380.
826
0.46
FA (S
h)67
1833
0530
0824
0000
9487
.90.
680.
130.
120.
2445
04
0.94
1835
0.5
190.
52FA
(Sh)
6718
3305
3008
2400
0094
89.3
0.79
0.28
0.34
0.24
451
30.
9543
301.
435
0.45
FA (S
h)67
1833
0530
0824
0000
9496
.51.
690.
470.
670.
4544
33
0.82
4027
1.5
280.
41FA
(Sh)
6718
3305
3008
2400
0095
01.2
0.92
0.28
0.42
0.25
453
20.
9946
271.
730
0.40
FA (S
h)67
1833
0530
0824
0000
9501
.71.
080.
390.
710.
2645
22
0.98
6624
2.7
360.
35FA
(Sh)
6718
3305
3008
2400
0095
07.4
0.78
0.26
0.40
0.26
453
21.
0051
331.
533
0.39
FA (S
h)67
1833
0530
0824
0000
9514
.10.
630.
210.
240.
2044
63
0.87
3832
1.2
330.
47FA
(Sh)
6718
3305
3008
2400
0095
16.5
0.65
0.25
0.26
0.32
452
40.
9840
490.
838
0.49
FA (S
h)67
4733
0530
0827
0000
9312
.21.
030.
480.
620.
3045
13
0.96
6029
2.1
470.
44FA
(Ri)
6747
3305
3008
2700
0093
12.5
0.82
0.33
0.36
0.29
451
30.
9644
351.
240
0.48
FA (R
i)67
4733
0530
0827
0000
9313
0.77
0.36
0.61
0.39
452
20.
9879
511.
647
0.37
FA (R
i)67
4733
0530
0827
0000
9313
.30.
630.
300.
350.
3045
33
0.99
5648
1.2
480.
46FA
(Ri)
6747
3305
3008
2700
0093
20.6
0.80
0.33
0.47
0.30
455
31.
0359
381.
641
0.41
FA (B
l)67
4733
0530
0827
0000
9320
.81.
180.
490.
870.
2645
52
1.03
7422
3.3
420.
36FA
(Bl)
NDI
C #
API N
umbe
rCo
re D
epth
(ft.)
S1S2
S3HI
OI
S2/S
3PI
Tabl
e 1
conti
nued
13
SRA
Tmax
Tmax
Calc
.S1
/TO
CM
adis
onTo
pBa
seTO
C(°
C)Q
ualit
y%
Ro
*100
Subu
nit
6747
3305
3008
2700
0093
21.4
0.95
0.28
0.63
0.25
451
20.
9666
262.
529
0.31
FA (B
l)67
4733
0530
0827
0000
9346
0.29
0.11
0.17
0.24
451
30.
9659
830.
738
0.39
FA (B
l)67
4733
0530
0827
0000
9347
1.01
0.40
0.92
0.43
452
20.
9891
432.
140
0.30
FA (B
l)67
4733
0530
0827
0000
9348
0.64
0.33
0.48
0.30
459
31.
1175
471.
652
0.41
FA (B
l)67
4733
0530
0827
0000
9349
0.84
0.80
0.72
0.53
453
30.
9986
631.
495
0.53
FA (B
l)67
4733
0530
0827
0000
9350
.35.
197.
109.
290.
8345
12
0.96
179
1611
.213
70.
43FA
(Bl)
6747
3305
3008
2700
0093
50.5
2.79
2.38
3.94
0.88
453
20.
9914
132
4.5
850.
38FA
(Bl)
6747
3305
3008
2700
0093
50.8
3.43
2.21
6.54
0.42
453
20.
9919
112
15.6
640.
25FA
(Bl)
6747
3305
3008
2700
0093
513.
942.
097.
910.
3945
22
0.98
201
1020
.353
0.21
FA (B
l)67
4733
0530
0827
0000
9351
.53.
650.
653.
890.
4845
32
0.99
107
138.
118
0.14
FA (B
l)67
4733
0530
0827
0000
9352
3.89
1.92
7.42
0.39
454
21.
0019
110
19.0
490.
21FA
(Bl)
6747
3305
3008
2700
0093
52.5
2.98
1.30
5.58
0.40
451
20.
9518
713
14.0
440.
19FA
(Bl)
6747
3305
3008
2700
0093
531.
261.
121.
280.
4544
63
0.87
102
362.
889
0.47
FA (B
l)67
4733
0530
0827
0000
9354
1.28
0.51
0.51
0.43
449
30.
9340
341.
240
0.50
FA (B
l)67
4733
0530
0827
0000
9354
.61.
620.
851.
100.
5344
73
0.89
6833
2.1
520.
44FA
(Bl)
6747
3305
3008
2700
0093
550.
670.
320.
390.
3245
73
1.07
5848
1.2
480.
45FA
(Bl)
6747
3305
3008
2700
0093
55.5
1.90
0.94
2.51
0.50
447
20.
8913
226
5.0
490.
27FA
(Bl)
6747
3305
3008
2700
0093
560.
420.
130.
110.
2646
03
1.13
2662
0.4
310.
54FA
(Bl)
6747
3305
3008
2700
0093
570.
960.
460.
630.
3445
23
0.98
6635
1.9
480.
42FA
(Bl)
6747
3305
3008
2700
0093
580.
830.
390.
760.
6935
35
-1.0
092
831.
147
0.34
FA (B
l)67
4733
0530
0827
0000
9358
.51.
430.
421.
750.
3544
82
0.90
122
245.
029
0.19
FA (B
l)67
4733
0530
0827
0000
9359
0.91
0.25
0.64
0.27
448
20.
9170
302.
427
0.28
FA (B
l)67
4733
0530
0827
0000
9360
1.13
0.37
1.51
0.24
447
20.
8813
421
6.3
330.
20FA
(Bl)
6747
3305
3008
2700
0093
611.
320.
821.
210.
4045
12
0.96
9230
3.0
620.
40FA
(Bl)
6747
3305
3008
2700
0093
620.
610.
330.
410.
3846
03
1.12
6762
1.1
540.
45FA
(Bl)
6747
3305
3008
2700
0093
830.
540.
280.
320.
3844
93
0.92
5970
0.8
520.
47FA
(Sh)
6747
3305
3008
2700
0093
83.5
1.31
1.16
1.24
0.58
450
30.
9395
442.
189
0.48
FA (S
h)67
4733
0530
0827
0000
9384
0.40
0.35
0.27
0.27
447
30.
8868
681.
088
0.56
FA (S
h)67
4733
0530
0827
0000
9384
.50.
690.
400.
580.
3745
23
0.97
8454
1.6
580.
41FA
(Sh)
6747
3305
3008
2700
0093
850.
470.
300.
290.
3544
53
0.84
6274
0.8
640.
51FA
(Sh)
6747
3305
3008
2700
0093
85.5
0.43
0.23
0.24
0.26
456
31.
0556
600.
953
0.49
FA (S
h)67
4733
0530
0827
0000
9386
0.36
0.15
0.19
0.26
447
30.
8953
720.
742
0.44
FA (S
h)
S3HI
OI
S2/S
3PI
NDI
C #
API N
umbe
rCo
re D
epth
(ft.)
S1S2
Tabl
e 1
conti
nued
14
Tabl
e 1
conti
nued
SRA
Tmax
Tmax
Calc
.S1
/TO
CM
adis
onTo
pBa
seTO
C(°
C)Q
ualit
y%
Ro
*100
Subu
nit
6747
3305
3008
2700
0093
86.5
1.65
0.90
1.80
0.43
445
20.
8410
926
4.2
550.
33FA
(Sh)
6747
3305
3008
2700
0093
870.
620.
190.
180.
2744
53
0.84
2944
0.7
310.
51FA
(Sh)
6747
3305
3008
2700
0094
091.
931.
131.
800.
3544
92
0.93
9318
5.1
590.
39FA
(Sh)
6747
3305
3008
2700
0094
101.
280.
570.
750.
4444
53
0.86
5934
1.7
450.
43FA
(Sh)
6747
3305
3008
2700
0094
150.
480.
240.
200.
3244
73
0.88
4267
0.6
500.
55FA
(Sh)
6747
3305
3008
2700
0094
19.3
1.76
0.54
2.43
0.28
448
20.
9013
816
8.7
310.
18FA
(Sh)
6747
3305
3008
2700
0094
200.
640.
330.
420.
2845
13
0.97
6644
1.5
520.
44FA
(Sh)
6747
3305
3008
2700
0094
22.3
0.72
0.43
0.48
0.22
451
30.
9567
312.
260
0.47
FA (S
h)68
3933
0530
0855
0000
9153
0.66
0.38
0.70
0.37
442
10.
8010
656
1.9
580.
35R
(Be)
6839
3305
3008
5500
0091
560.
940.
630.
600.
4144
33
0.81
6444
1.5
670.
51R
(Be)
6839
3305
3008
5500
0091
57.4
1.29
0.44
0.79
0.48
439
20.
7461
371.
634
0.36
R (B
e)68
3933
0530
0855
0000
9158
.22.
491.
684.
550.
8244
11
0.78
183
335.
567
0.27
R (B
e)68
3933
0530
0855
0000
9163
0.50
0.20
0.16
0.31
439
40.
7532
620.
540
0.56
R (B
e)68
3933
0530
0855
0000
9165
0.27
0.08
0.02
0.22
429
40.
567
810.
130
0.80
R (B
e)68
3933
0530
0855
0000
9215
1.50
0.60
1.30
0.36
440
10.
7787
243.
640
0.32
R (M
i)68
3933
0530
0855
0000
9217
1.04
0.46
0.47
0.47
430
30.
5845
451.
044
0.49
R (M
i)68
3933
0530
0855
0000
9218
1.26
0.61
0.77
0.71
427
30.
5261
561.
148
0.44
R (M
i)68
3933
0530
0855
0000
9219
0.82
0.25
0.35
0.29
440
20.
7543
351.
230
0.42
R (M
i)68
3933
0530
0855
0000
9221
0.93
0.45
0.33
0.46
436
30.
6935
490.
748
0.58
R (M
i)68
3933
0530
0855
0000
9222
1.06
0.44
0.35
0.67
426
30.
5133
630.
542
0.56
R (M
i)68
3933
0530
0855
0000
9223
1.13
0.85
0.99
0.65
424
50.
4788
581.
575
0.46
R (M
i)68
3933
0530
0855
0000
9223
.11.
490.
530.
830.
9542
43
0.47
5664
0.9
360.
39R
(Mi)
6839
3305
3008
5500
0092
250.
680.
370.
350.
4443
13
0.59
5165
0.8
540.
51R
(Mi)
6839
3305
3008
5500
0092
270.
850.
560.
830.
7842
55
0.50
9892
1.1
660.
40R
(Mi)
6839
3305
3008
5500
0092
290.
790.
360.
400.
6342
53
0.50
5180
0.6
460.
47R
(Mi)
6839
3305
3008
5500
0092
310.
650.
360.
410.
6142
53
0.49
6394
0.7
550.
47R
(Mi)
6839
3305
3008
5500
0092
31.7
1.24
0.46
0.64
0.91
427
30.
5252
730.
737
0.42
R (M
i)68
3933
0530
0855
0000
9233
0.35
0.23
0.06
0.30
439
40.
7417
860.
266
0.79
R (M
i)68
3933
0530
0855
0000
9235
0.53
0.22
0.35
0.30
442
20.
8066
571.
242
0.39
R (M
i)68
3933
0530
0855
0000
9250
2.04
0.74
0.77
0.70
431
30.
6038
341.
136
0.49
FA (R
i)68
3933
0530
0855
0000
9250
.22.
261.
181.
661.
4142
15
0.41
7362
1.2
520.
42FA
(Ri)
6839
3305
3008
5500
0092
520.
620.
220.
210.
3043
84
0.72
3448
0.7
350.
51FA
(Ri)
S3HI
OI
S2/S
3PI
NDI
C #
API N
umbe
rCo
re D
epth
(ft.)
S1S2
15
Tabl
e 1
conti
nued
SRA
Tmax
Tmax
Calc
.S1
/TO
CM
adis
onTo
pBa
seTO
C(°
C)Q
ualit
y%
Ro
*100
Subu
nit
6839
3305
3008
5500
0092
540.
530.
450.
260.
4043
44
0.64
4975
0.7
850.
63FA
(Ri)
6839
3305
3008
5500
0092
560.
591.
130.
590.
4243
14
0.59
100
711.
419
20.
66FA
(Ri)
6839
3305
3008
5500
0092
580.
980.
440.
470.
3943
93
0.74
4840
1.2
450.
48FA
(Ri)
6839
3305
3008
5500
0092
600.
600.
270.
260.
2943
93
0.75
4348
0.9
450.
51FA
(Bl)
6839
3305
3008
5500
0092
621.
110.
400.
420.
3644
13
0.78
3832
1.2
360.
49FA
(Bl)
6839
3305
3008
5500
0092
640.
920.
560.
520.
5443
93
0.74
5759
1.0
610.
52FA
(Bl)
6839
3305
3008
5500
0092
660.
290.
280.
170.
2543
24
0.62
5986
0.7
970.
62FA
(Bl)
6839
3305
3008
5500
0092
800.
730.
400.
370.
5442
15
0.42
5174
0.7
550.
52FA
(Bl)
6839
3305
3008
5500
0092
821.
430.
910.
960.
7443
63
0.69
6752
1.3
640.
49FA
(Bl)
6839
3305
3008
5500
0092
840.
370.
320.
330.
2842
25
0.43
8976
1.2
860.
49FA
(Bl)
6839
3305
3008
5500
0092
84.8
1.43
0.81
0.71
0.83
428
30.
5450
580.
957
0.53
FA (B
l)68
3933
0530
0855
0000
9286
1.36
0.52
0.41
0.71
424
30.
4730
520.
638
0.56
FA (B
l)68
3933
0530
0855
0000
9288
0.28
0.20
0.13
0.23
441
40.
7846
820.
671
0.61
FA (B
l)68
3933
0530
0855
0000
9290
0.41
0.41
0.17
0.37
445
40.
8641
900.
510
00.
71FA
(Bl)
6839
3305
3008
5500
0092
921.
670.
500.
710.
5543
63
0.68
4333
1.3
300.
41FA
(Bl)
6839
3305
3008
5500
0092
940.
460.
150.
170.
2644
64
0.86
3757
0.7
330.
47FA
(Bl)
6839
3305
3008
5500
0092
960.
210.
110.
130.
1344
34
0.81
6262
1.0
520.
46FA
(Bl)
6839
3305
3008
5500
0092
980.
280.
170.
200.
1745
94
1.10
7161
1.2
610.
46FA
(Bl)
6839
3305
3008
5500
0093
000.
390.
310.
230.
1745
24
0.98
5944
1.4
790.
57FA
(Bl)
6839
3305
3008
5500
0093
021.
180.
481.
820.
2044
62
0.87
154
179.
141
0.21
FA (B
l)68
3933
0530
0855
0000
9304
0.26
0.17
0.20
0.23
451
30.
9577
880.
965
0.46
FA (B
l)68
3933
0530
0855
0000
9306
0.35
0.21
0.26
0.21
445
30.
8674
601.
260
0.45
FA (B
l)68
3933
0530
0855
0000
9308
0.28
0.17
0.23
0.18
445
30.
8582
641.
361
0.43
FA (S
h)68
3933
0530
0855
0000
9310
0.60
0.26
0.39
0.18
453
30.
9965
302.
243
0.40
FA (S
h)68
3933
0530
0855
0000
9312
0.81
0.80
0.71
0.28
446
30.
8688
352.
599
0.53
FA (S
h)68
3933
0530
0855
0000
9314
0.24
0.23
0.19
0.22
448
30.
9079
920.
996
0.55
FA (S
h)72
2833
0530
0959
0000
8982
.10.
900.
350.
460.
5343
53
0.67
5159
0.9
390.
43R
(Be)
7228
3305
3009
5900
0089
85.0
1.19
0.46
0.59
0.79
440
40.
7550
660.
739
0.44
R (B
e)72
2833
0530
0959
0000
8987
.089
88.0
1.06
0.79
0.92
0.46
438
30.
7387
432.
075
0.46
R (M
i)72
2833
0530
0959
0000
8990
.089
91.0
0.92
0.67
0.68
0.55
430
40.
5974
601.
273
0.50
R (M
i)72
2833
0530
0959
0000
8990
.80.
720.
710.
770.
6943
75
0.71
107
961.
199
0.48
R (M
i)72
2833
0530
0959
0000
8996
.089
97.0
0.91
0.43
0.79
0.67
439
30.
7487
741.
247
0.35
R (M
i)
S3HI
OI
S2/S
3PI
NDI
C #
API N
umbe
rCo
re D
epth
(ft.)
S1S2
16
Tabl
e 1
conti
nued
SRA
Tmax
Tmax
Calc
.S1
/TO
CM
adis
onTo
pBa
seTO
C(°
C)Q
ualit
y%
Ro
*100
Subu
nit
7228
3305
3009
5900
0089
99.0
9000
.00.
820.
490.
540.
6543
33
0.63
6679
0.8
600.
48R
(Mi)
7228
3305
3009
5900
0090
00.5
1.22
0.55
1.14
0.62
437
30.
7193
511.
845
0.33
R (M
i)72
2833
0530
0959
0000
9002
.090
03.0
0.64
0.28
0.43
0.54
426
40.
5067
840.
844
0.39
R (M
i)72
2833
0530
0959
0000
9005
.090
06.0
1.05
0.44
0.51
0.66
426
30.
5149
630.
842
0.46
R (M
i)72
2833
0530
0959
0000
9005
.11.
090.
550.
670.
6543
53
0.66
6160
1.0
500.
45R
(Mi)
7228
3305
3009
5900
0090
06.7
1.18
0.54
0.67
0.75
433
30.
6357
640.
946
0.45
R (M
i)72
2833
0530
0959
0000
9008
.090
09.0
0.84
0.31
0.44
0.60
428
30.
5452
710.
737
0.41
R (M
i)72
2833
0530
0959
0000
9011
.090
12.0
0.60
0.34
1.41
0.56
392
5-1
.00
235
932.
557
0.19
R (M
i)72
2833
0530
0959
0000
9051
.890
52.8
2.17
0.98
2.71
0.58
440
10.
7612
527
4.7
450.
27FA
(Bl)
7228
3305
3009
5900
0090
52.5
9053
.01.
900.
623.
650.
5344
41
0.83
192
286.
933
0.15
FA (B
l)72
2833
0530
0959
0000
9053
.090
54.0
1.13
0.50
1.29
0.50
445
10.
8411
444
2.6
440.
28FA
(Bl)
7228
3305
3009
5900
0090
54.0
9055
.00.
870.
330.
710.
4644
41
0.83
8253
1.5
380.
32FA
(Bl)
7228
3305
3009
5900
0090
55.0
9056
.00.
920.
390.
780.
4444
82
0.90
8548
1.8
420.
33FA
(Bl)
7228
3305
3009
5900
0090
56.0
9057
.01.
400.
420.
890.
5144
31
0.81
6436
1.7
300.
32FA
(Bl)
7228
3305
3009
5900
0090
57.0
9058
.00.
810.
360.
650.
3744
61
0.87
8046
1.8
440.
36FA
(Bl)
7228
3305
3009
5900
0090
58.0
9059
.00.
570.
280.
680.
3144
32
0.81
119
542.
249
0.29
FA (B
l)72
2833
0530
0959
0000
9059
.090
60.1
1.14
0.32
0.80
0.42
445
10.
8570
371.
928
0.29
FA (B
l)72
2833
0530
0959
0000
9060
.190
61.0
0.76
0.30
0.71
0.33
446
20.
8793
432.
239
0.30
FA (B
l)72
2833
0530
0959
0000
9061
.090
62.0
0.85
0.36
0.92
0.42
446
10.
8610
849
2.2
420.
28FA
(Bl)
7228
3305
3009
5900
0090
62.0
9062
.90.
550.
220.
440.
4144
22
0.79
8075
1.1
400.
33FA
(Bl)
7228
3305
3009
5900
0090
62.9
9063
.80.
700.
260.
470.
3444
62
0.86
6749
1.4
370.
36FA
(Bl)
7228
3305
3009
5900
0090
63.8
9064
.50.
860.
330.
780.
4244
32
0.82
9149
1.9
380.
30FA
(Bl)
7228
3305
3009
5900
0090
64.5
9065
.01.
190.
401.
130.
4944
11
0.78
9541
2.3
340.
26FA
(Bl)
7228
3305
3009
5900
0090
65.0
9065
.80.
900.
390.
720.
4744
41
0.83
8052
1.5
430.
35FA
(Bl)
7228
3305
3009
5900
0090
65.8
9067
.40.
570.
320.
490.
4343
83
0.72
8675
1.1
560.
40FA
(Bl)
7228
3305
3009
5900
0090
67.4
9068
.50.
770.
420.
670.
4145
01
0.94
8753
1.6
550.
39FA
(Bl)
7228
3305
3009
5900
0090
68.5
9069
.01.
560.
592.
120.
5144
21
0.79
136
334.
238
0.22
FA (B
l)72
2833
0530
0959
0000
9069
.090
70.0
0.81
0.47
0.84
0.42
441
20.
7810
452
2.0
580.
36FA
(Bl)
7228
3305
3009
5900
0090
70.0
9071
.70.
770.
400.
730.
4744
72
0.88
9561
1.6
520.
35FA
(Bl)
7228
3305
3009
5900
0090
71.7
9072
.00.
890.
430.
890.
5843
72
0.71
100
651.
548
0.33
FA (B
l)72
2833
0530
0959
0000
9121
.091
22.0
0.81
0.50
0.50
0.50
436
30.
6962
621.
062
0.50
FA (S
h)72
2833
0530
0959
0000
9121
.30.
850.
590.
960.
5544
43
0.84
113
651.
769
0.38
FA (S
h)
S3HI
OI
S2/S
3PI
NDI
C #
API N
umbe
rCo
re D
epth
(ft.)
S1S2
17
Tabl
e 1
conti
nued
SRA
Tmax
Tmax
Calc
.S1
/TO
CM
adis
onTo
pBa
seTO
C(°
C)Q
ualit
y%
Ro
*100
Subu
nit
7228
3305
3009
5900
0091
25.0
9126
.00.
680.
390.
790.
4243
63
0.70
116
621.
957
0.33
FA (S
h)72
2833
0530
0959
0000
9125
.50.
560.
280.
380.
3544
03
0.77
6863
1.1
500.
42FA
(Sh)
7228
3305
3009
5900
0091
35.8
0.92
0.33
1.17
0.40
444
10.
8412
743
2.9
360.
22FA
(Sh)
7228
3305
3009
5900
0091
36.0
9137
.00.
490.
180.
340.
4144
22
0.80
6984
0.8
370.
35FA
(Sh)
7228
3305
3009
5900
0091
36.3
1.02
0.37
1.74
0.50
440
10.
7617
149
3.5
360.
18FA
(Sh)
7228
3305
3009
5900
0091
64.7
2.38
2.06
2.19
0.70
435
30.
6892
293.
187
0.48
FA (u
n)72
2833
0530
0959
0000
9165
.091
66.0
0.78
0.32
0.36
0.51
438
30.
7346
650.
741
0.47
FA (u
n)72
2833
0530
0959
0000
9166
.00.
460.
190.
100.
5042
74
0.52
2210
90.
241
0.66
FA (u
n)72
2833
0530
0959
0000
9170
.091
71.0
0.62
0.21
0.16
0.47
435
40.
6726
760.
334
0.57
FA (u
n)72
2833
0530
0959
0000
9176
.091
77.0
0.81
0.43
0.45
0.44
436
40.
7056
541.
053
0.49
FA (u
n)72
2833
0530
0959
0000
9176
.51.
210.
580.
620.
6143
74
0.70
5150
1.0
480.
48FA
(un)
7228
3305
3009
5900
0091
78.0
9179
.00.
640.
300.
280.
4943
44
0.65
4477
0.6
470.
52FA
(un)
7228
3305
3009
5900
0091
80.0
9181
.00.
560.
260.
380.
3743
44
0.66
6866
1.0
460.
41FA
(un)
7228
3305
3009
5900
0091
83.0
9184
.00.
880.
270.
210.
4543
84
0.72
2451
0.5
310.
56FA
(un)
7228
3305
3009
5900
0091
83.6
4.14
2.05
5.12
0.90
441
10.
7712
422
5.7
500.
29FA
(un)
7228
3305
3009
5900
0093
30.4
0.66
0.24
0.34
0.77
441
30.
7852
117
0.4
360.
41FA
(un)
7228
3305
3009
5900
0093
32.5
9333
.50.
430.
120.
190.
3742
64
0.51
4486
0.5
280.
39FA
(un)
7228
3305
3009
5900
0093
33.0
0.35
0.15
0.28
0.36
423
40.
4680
103
0.8
430.
35FA
(un)
7228
3305
3009
5900
0093
70.0
9370
.50.
520.
250.
250.
4643
84
0.73
4888
0.5
480.
50FA
(un)
7228
3305
3009
5900
0094
15.0
9415
.30.
510.
390.
420.
4844
24
0.80
8294
0.9
760.
48FA
(un)
7228
3305
3009
5900
0094
18.0
9419
.00.
530.
310.
470.
4244
03
0.76
8979
1.1
580.
40FA
(un)
7228
3305
3009
5900
0094
19.1
1.29
0.59
1.26
0.89
436
30.
6998
691.
446
0.32
FA (u
n)72
2833
0530
0959
0000
9429
.40.
520.
280.
380.
3644
04
0.76
7369
1.1
540.
42FA
(un)
7228
3305
3009
5900
0094
44.0
9445
.00.
540.
230.
210.
5643
04
0.59
3910
40.
443
0.52
FA (u
n)72
2833
0530
0959
0000
9448
.094
49.0
0.60
0.45
0.44
0.57
436
40.
6973
950.
875
0.51
FA (u
n)72
2833
0530
0959
0000
9457
.094
58.0
0.76
0.44
0.53
0.42
439
40.
7470
551.
358
0.45
FA (u
n)72
2833
0530
0959
0000
9457
.30.
670.
380.
420.
4743
44
0.66
6370
0.9
570.
48FA
(un)
7228
3305
3009
5900
0094
60.0
0.23
0.13
0.09
0.35
474
41.
3739
152
0.3
570.
59FA
(un)
7228
3305
3009
5900
0094
61.0
9462
.00.
670.
480.
450.
5642
34
0.45
6784
0.8
720.
52FA
(un)
7228
3305
3009
5900
0094
61.6
1.07
0.65
0.71
0.70
423
40.
4666
651.
061
0.48
FA (u
n)72
2833
0530
0959
0000
9462
.01.
291.
040.
931.
0642
24
0.44
7282
0.9
810.
53FA
(un)
7228
3305
3009
5900
0094
78.5
9479
.50.
600.
810.
380.
4143
74
0.71
6368
0.9
135
0.68
FA (u
n)
S3HI
OI
S2/S
3PI
NDI
C #
API N
umbe
rCo
re D
epth
(ft.)
S1S2
18
Tabl
e 1
conti
nued
SRA
Tmax
Tmax
Calc
.S1
/TO
CM
adis
onTo
pBa
seTO
C(°
C)Q
ualit
y%
Ro
*100
Subu
nit
7228
3305
3009
5900
0094
79.3
0.70
0.36
0.42
0.47
437
40.
7060
670.
951
0.46
FA (u
n)72
2833
0530
0959
0000
9484
.01.
070.
490.
670.
5244
13
0.77
6349
1.3
460.
42FA
(un)
*Tm
ax Q
ualit
y: 1
= e
xcel
lent
, 2 =
goo
d, 3
= q
uest
iona
ble,
4 =
que
stio
nabl
e/un
relia
ble,
5 =
unr
elia
ble
*Mad
ison
subu
nits
:R=
Ratc
liffe
Inte
rval
;FA
=Fr
obish
er-A
lida;
Bl=
Blue
llsu
bint
erva
l;M
i=M
idal
esu
bint
erva
l;Sh
=Sh
erw
ood
subi
nter
val;
Be=
Bere
ntse
n su
bint
erva
l; Ri
= R
ival
subi
nter
val;
un =
und
iffer
entia
ted
*Abb
revi
atio
ns:C
alc.
=Ca
lcul
ated
;ft.
=fe
et;H
I=Hy
drog
enIn
dex
(mg
HC/g
TOC)
;OI=
Oxy
gen
Inde
x(m
gCO
2/g
TOC)
;PI=
Prod
uctio
nIn
dex;
SRA
=So
urce
Roc
k An
alyz
er; T
OC
= To
tal O
rgan
ic C
arbo
n (b
y w
eigh
t per
cent
);
S3HI
OI
S2/S
3PI
NDI
C #
API N
umbe
rCo
re D
epth
(ft.)
S1S2
20
10
00
30
Gamma Ray
Caliper
0.3 -0.1
Density Porosity0.3 -0.1
Neutron Porosity0.2 2000
Resistivity
9,40
09,
425
0 50
6 16
#671833-053-00824-00-00
Pennzoil Co. and DepcoFederal #22-32K.B. = 2,196 ft
70
60
50
40
80
9,45
09,
475
9,47
5
A
A
L
L
L
LL
LL
LL
h
h
h
WR
?
?
?
Lam
inae
Geo
met
ry
Colo
r
Mudst.
Wackest.
Packst.
Grainst.
FossilsSed.Str.
40
30
20
Gamma Ray
Core GR
0.3 -0.1Density Porosity
0.3 -0.1Neutron Porosity
0.2 2000Resistivity
9,32
59,
350
9,30
0
0 100
100 300
#674733-053-00827-00-00
Shell Oil Co.Mitten #12-10K.B. = 2,270 ft
90
80
70
60
50
9,37
59,
400
core + 2 �. = ~logcore - 3 �. = ~log
00
L
LL
LL
LL
LL
LL
h
h
h
Lam
inae
Geo
met
ry
Colo
r
Mudst.
Wackest.
Packst.
Grainst.
FossilsSed.Str.
9,27
5
core - 12 �. = ~log
60
50
40
9,45
0
30
20
10
00
90
9,40
09,
425
80
70
60
50
40
9,35
09,
375
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
L
L
L
L
WR
A
A
Mid
ale
subi
nter
val
Riv
al su
bint
erva
l
Fro
bis
her
-Ali
da
In
terv
al
Rat
cliff
e In
terv
alB
luel
l sub
inte
rval
Sher
woo
d su
bint
erva
l
Lam
inae
Geo
met
ry
Colo
r
Mudst.
Wackest.
Packst.
Grainst.
FossilsSed.Str.
Caliper0.3 -0.1
Density Porosity0.3 -0.1
Neutron Porosity
0.2 2000Resistivity
Core GR
6 16
Gamma Ray0 100
100 450
#641433-053-00739-00-00
Shell Oil Co.USA 21-8
K.B. = 2,334 ft
core + 4 �. = ~log20
10
00
9,32
59,
300
9,35
0
80
70
60
50
90
9,27
59,
250
30
20
40
9,22
5
L
L
L
TS
TS
TS
TS
TS
TS
Gamma Ray
Caliper
0.3 -0.1Density Porosity
0.3 -0.1Neutron Porosity
0.2 2000Resistivity
0 75
6 16
#683933-053-00855-00-00
Shell Oil Co.USA #43-11
K.B. = 2,065 ft
Lam
inae
Geo
met
ry
Colo
r
Mudst.
Wackest.
Packst.
Grainst.
FossilsSed.Str.
010
20
0
0
0
10
200010
10
101020
0
10
202030
30
2020
00
20
0
0
20
20
20
0 4Miles
c
b
a
d
A’
A
#6747
#6839
#7228
#6414
#6718
- styolitic
- contorted lam./bedding
- lithoclast/s
- nodule/s
- pyrite
- lag
- wave ripple laminae
- microbiolites
Sedimentary/Core Symbols:
- breccia
- rip up clasts
- Ooids
- Oncolite
- peloids
L
- scouring
- burrows
S
- Brachiopod
- Shells
- Crinoid/s
- Gastropod/s
- Ostracod/s
- Bryzoan
- Solitary (rugose) Coral
- Tabulate Coral
- Cross-bedding
- anhydrite nodule/sA
- horizontal burrowsh
L
WR
- Fossil bed/laminae
- LimestoneCore Lithology:
- Dolomi�c Limestone
- Argillaceous Limestone
- Dolostone
- Calcareous Dolostone
- Anhydrite
- Dolomi�c anhydrite
- Birdseye structure
- Mud cracks
North Dakota Geological Survey Geological Investigations No. 255 - Plate I
Edward C. Murphy - State GeologistLynn D. Helms, Director Dept. of Mineral Resources
Explanation: Stratigraphic cross-section (above) of the Sherwood, Bluell, Rival, and Midale subintervals of the Mississippian Madison Group with wireline logs and core description illustrations. Isopach map (left) of the gross thickness of the high TOC lower Bluell facies. Contours are in 5-foot intervals and the brown contour fill is in 10-foot intervals. Small light grey circles are the wireline log well control and the large black circles are the core control wells. See Figure 1 for study area location. Red lines depict documented struc-tures: a = Mondak monocline, b = Beaver Creek anticline, c = Red Wing Creek structure, d = Little Knife anticline
Stratigraphic Cross-SectionPlate I: