pne g9 gasbuggy

8/7/2019 pne g9 gasbuggy

1/14

This pap is t

i

DRILLING AND TESTING OPERATIONSFOR PROJECT GASBUGGY

BYW. G. Cutler a n d H. L.Kendnck, Members AIME, E1 Paso Natural Gas c o m p w y ,

Farmington, New Mexico

be presented a t the 43rd Annual Fall Meeting of the Society ofPetroleum Engineers ofAIME to be heldin Houston, Texas on September 29 to October 2, 1968.

ABSTRACT

This paper dea ls with mechanics of drilling and tes-

ting of the Gasbuggy sit e wells in the pre-shot and post -shot program. The information obtained from pre-shot well

drilling and production tes ting of GB-1 and GB-2 wells

confirmed the te st s it e acceptability. The drilling discus-sion outlines the hole size, casing program, mud and gasdrilling requirements, hydrological testing, coring, natu-

ral gas flow measurement and logging program.

Hydrological testing of water-bearing strata above

the Pictured Cliffs zone wa s performed to determine the

quantity and quality of mobile water that might affect the

experiment. The natural gas flow and shut-in well test da-t a obtained while drilling and following completion of

each well are presented. The mechanics of emplacement

hole drilling, casing, loading and stemming for shot con-

tainment are dis cussed.

Following the detona tion of th e device on December10, 1967 the re-entry into the emplacement hole for pre-liminary sampling and chimney height determination is

described. Post-shot pres sure build-up data and gas sam-pling procedures are described. The re-entry drilling intoGB-2R is described and the la tes t available test data rel-ative to the flow rates and pressure data are presented.

INTRODUCTION

Project Gasbuggy moved from a four-year planning

stage to the site confirmation stage immediately follow-

ing the signing of a contract by the Atomic Energy Com-

mission, the Department of the Interior, and El Paso Nat-

ural Gas cl)mpany for the jointly sponsored project onJanuary 31, 1967. Obtaining tes t si te confirmation wasthe fi rst order of busines s and the firs t well, GB-1, was

spudded on February 11, 1967.

The purpose of GB-1 was (1) to evaluate the water-bearing strata above the Pictured Cliffs zone for quantityand quality, (2) to evaluate the natural gas flow and shut-

in pressure data of the objective Pictured Cliffs reservoir

and (3) to obtain formation properties for reservoir evalu-

ation of the gas-bearing Pictured Cliffs zone and associ -

ated formations.

A producing Pictured Cliffs well drilled in 1956 waslocated 33 0 feet from the proposed GB-1 location. Thiswell, the San Juan 29-4 Unit No. 10, was dri lled and com-pleted with 9-5/8-inch surface casing se t a t 124 feet,5-1/2-inch production casing set in a mud-drilled 8-3/4-inch hole through the Pictured Cliffs formation to 4203

feet. The well was selectively perforated, sand-waterfractured and completed with 2-inch tubing. The well' s

calculated open flow at t he end of a three-hour blow down

through a 3/4-inch choke was 1400 Mcfd. The initial de -liverability to the pipeline was 60 Mcfd at 50 percent ofthe wellhead shut-in pressure. The original bottom hole

pressure was calculated to be 1230 psig at 4156 feet with

a reservoir temperature of 130' F. This w e 11 produced81,854 M c f from initial production in 1957 to the time itwas shut in during October, 1967.

GB-1 WELL PROGRAMThe drilling program for GB-1 consisted of setting

13-3/8-inch surface casing at 502 feet. A conventional12-1/4-inch hole was mud-drilled to a depth 45 fee t abovethe Ojo Alamo formation. From this point diamond coringwith an 8-3/4-inch by 5-1/4-inch core bit was initiatedand the u p p e r portion of t he Ojo Alamo was cored andswab teste d under a packer to determine the ra te of water

entry. The lower portion of the Ojo Alamo wa s also cored

and similarly tested. Results of e ach te st indicated a low

mobility water factor and a water quality not suitable for

domestic use.

Coring was continued to the casing point above the

Fruitland formation and after the cored hole was reamed

9-5/8-inch casing was run and ce m e n t e d at 3755 feet.Full hole 8-3/4-inch by 5-1/4-inch coring with gas circu-lation was initiated immediately below the casing to the

top of the Pic ture d Cliffs where the core hole siz e was

reduced to 6-1/4-inch and continued to the well's totaldepth of4320 feet, or 120 feet into the L e w i s shale. Atota l of 870 fee t of continuous coring was performed with

a core recovery of 98 percent. Throughout the gas coringoperation natural gas flow gauges were recorded at each

drill pipe connection and when the c o r e barrel was pul-

led. Figure 1illustrates the natural gas flow data secur-ed during the coring operation.


2/14

DISCLAIMER

This report was prepared as an account of work sponsored by anagency of the United States Government. Neither the United StatesGovernment nor any agency Thereof, nor any of their employees,makes any warranty, express or implied, or assumes any legalliability or responsibility for the accuracy, completeness, orusefulness of any information, apparatus, product, or processdisclosed, or represents that its use would not infringe privatelyowned rights. Reference herein to any specific commercial product,process, or service by trade name, trademark, manufacturer, orotherwise does not necessarily constitute or imply its endorsement,recommendation, or favoring by the United States Government or anyagency thereof. The views and opinions of authors expressed hereindo not necessarily state or reflect those of the United StatesGovernment or any agency thereof.


3/14

DISCLAIMER

Portions of this document may be illegible inelectronic image products. Images are producedfrom the best available original document.


4/14

A short duration, ls-hour, pressure build-up test wa sconducted when c o r i n g reached the top of the Pictured

Cliffs. A natural g as flow rate of 100 Mcfd was measured

for the Fruitland z o n e immediately prior to shutt ing in

th e well.

At tot al d e p t h the cored i n t e r v a l wa s reamed to

8-3/4-inches. A seri es of dry hole logs , directional sur-veys, borehole photos and packer flow meter surveys were

completed prior to running the 2-inch production tubing.

Flow testing was resumed following a seven-day shut-in

period with an isochronal type test being conducted with

six-hour flow periods at r a t e s of 90, 440, 275, and 146

Mcfd.

After a review of t he da ta obtained during the drill-ing and the i n i t i a l tes tin g of GB-1 the technical repre-

sen tat ive s of the participating organizations recommend-

ed, and secured, site acceptability.

GB-2 WELL PROGRAM

Immediately after site acceptance the GB-2 well wa s

comm e n c ed to confirm the continuity of dat a obtainedfrom GB-1. The well was located 470 feet from GB-1 and300 feet from the proposed emplacement hole location.

The relative well locations ar e shown in Figure 2.

Surface 9-5/8-i n c h casing was set at 496 feet, andan 8-3/4-inch hole was mud-drilled through the Ojo Alamoformation where a hydrological swab test was conducted

in a similar manner as employed in GB-1. Drilling wa s re-

sumed to the casing point at the Fruitland-Pictured Cliffs

c o n t a c t where "-inch casing w a s run and cemented at3920 feet.

Below the c a s i n g a 6-1/4-i n c h by 3-1/2-inch ga scoring program was pursued to total depth of 4260 feet.Mud or water entry, a t t r i b u t e d to drilling the naturallyfractured upper Pictured Cliffs with mud prior to runningcasing, necess itate d remedial cement squeeze operations

at the c a s i n g seat after reaching 4046 feet before suc-cessful gas coring could be accomplished to total depth.

As in GB-1, natural gas gauges were taken with eachdrillp i p e connection and trip with the core barrel. The flow

rates ranged from 4 to 43 Mcfd in the cored interval. Three

h u n d r e d forty feet were co re d with a 92 percent corerecovery.

A ser ie s of dry hole logs, directional surveys, bore-

hole ca m e r a , packer flow me t e r and bottom hole fluidsampler runs and surveys preceded the landing of 2-inch

production tubing, completing the well.

PRE - SHOT TESTING

A shut-in pressure build-up t e s t of GB-2 was initi-ated and continued for nine w e e ks before the well wasb 1own, without restriction, for eight days to a rate ap-

proaching stabilization at 4 Mcfd. The w e 11 was again

shut in and pressure build up recorded until the hole wa s

mud ded up, wet hole l o g g i n g completed and the well

stemmed for shot containment.

A s e c o n d GB-1 isochronal type test was initiated

after drilling GB-2 and was conducted using six-hour flow

intervals at ra tes of 415, 264, 148 and 75 Mcfd, with the

la st ra te being continued for 30,days . A third flow testwas later made in which the well was produced at regu-

lated surface rates to achieve a constant reservoir volume

withdrawal. The surface rate wa s regulated from 738 Mcfd

init ially to 94 Mcfd at th e conclusion ofthe 6-day period.

Figure 3 shows the wellhead pressures of GB-1 andSan Juan 29-4 Unit No. 10 and the inte rference recorded

between these wells. Immediately prior to final logging

and stemming for s h o t containment the GB-1 w e l l waspr od uc ed through a 3/4-inch choke for five days. Therate was measured at 447 Mcfd at the end of three hoursand 35 Mcfd at the end of the five days. Pressure inter-ference between GB-1 and GB-2 was not observed duringthis period.

THE EMPLACEMENT HOLE

The drilling of GB-E, the nuclear d e v ic e emplace-

ment hole, was s t a r t e d on June 25, 1967. A dry h o 1edigger was employed prior to assembling the drilling rig

to set 30-inch surface casing at 49 feet . A 13-3/4-inchpilot hole was drilled to a depth of 4350 feet and subse-

quently reamed from a 13-3/4-inch to 28-inch hole diam-eter employing both platform r e a m e r s and conventional

pilot and s t r i n g reamers. Specially fabricated casing of20-inch 0. D. was run to a d e p t h of 4324 feet. The pipe

wa s cemented in a conventional oil field manner in three

stages. The first stage employed float shoe, float collaand a baffle collar arrangement, while the second stage

was placed t h ro u g h a cement collar at 3550 eet.Thethird stage used a cement collar at 1800 feet. In excess

of 19,000 cubic feet of cement slurry was used in cement-ing. The 20-inch cas ing was designed to prevent collapse,

assuming that the casing would be dry at the time of de-

vice emplacement. Reinforcing bands were added at 5 and

6 foot in terva ls on the bottom 1460 feet of the cas ing to

achieve the desired collapse design factor.

The 20-i n c h casing from the s u r fa c e to 2400 feetweighed 130 pounds per foot with a wall thickness of .64

inch. The balance of th e casi ng weighed 160 pounds per

foot with a wall th ickness of .77 inch. While cementing,

the stage c o 11 a r at 3550 feet was not closed and later

permitted Ojo Alamo water to leak into the casing. It wa s

decided to run the device with water in the casing rather

than risk s q u e e z e c e m e n t i n g the stage col larpor ts.

The nuclear device canister, shown in Figure 4, was

moved over the emplacement hole with a crane and later

lowered into the 20-inch cased hole on 7-inch casing. The

firing cable is shown extending from above the canister

and running over the rounded crutch which was u s ed to

prevent damage to the cable.

One joint of the 7-inch casing, noted in Figure 5,was made up on th e top of t he cani ster and lowered into

the hole. After skidding the rig over the emplacement hole

the device was lowered on the 7-inch casing to a depth


5/14

of 4240 feet. Some 13 c a b1e s to the device and variousinstruments were supported with clamps between the cen-tralizer blades positioned on every other casing joint and

and w e r e taped to t he ca sing to minimize damage while

lowering.

STEMMING OPERATIONS

The slot ted join ts of c a s i n g were run at predeter-

mined depths to permit placement of the cement used for

the stemming operation. Tubing was run in side the "-inchcasi ng and the cement mixture pumped through the se sl ot s

to fill the annulus between the 7-inch and 20-inch casing.Three s t a ge s of cement were placed from 4228 feet to

3000 feet, 10/80 mesh sand was placed from 3000 feet to2500 feet, cement from 2500 feet to 1500 feet, and sandto within 50 feet of the surface. A chemical grout of 750

gallons was p u m p e d into the top 50 feet of the 20-inch

casing.

Figure 6 d i a g r a m s th e stemming of GB-E, GB-2,San Juan 29-4 Unit No. 10, and the placing of instrument sand stemming ofGB-1 following the completion of preshotproduction testi ng and th e m u d d i n g up of the dry hole

sect ions for wet hole l ogs and surveys. GB-1 was equipped

with instruments and stemmed in the same operation. The

instruments and c a b 1e s w e r e attached to 1520 feet of2-3/8-inch fiberglass tubing and lowered into the hole to4250 fe e t on conventional s t e e1 tubing. Cem e n t waspumped through the tubing string into the open hole sec-tion and the 9-5/8-inch by 2-3/8-inch tubing annulus from4250 feet to 3000 feet. Drilling mud stemmed the balanceof the hole to the surface.

The San Juan 29-4 Unit No. 10 was stemmed by theus e of sand placed in the bottom of the hole opposite the

perforated intervals and a bridge plug s et above the sa nda t 3880 feet . Cement was then p l a c e d from the bridgeplug to 2940 feet and the balance of th e casing was filledwith mud to the surface. GB-2 was stemmed with cementfr o m 4220 feet to 3000 feet and the balance of the holewas filled with drilling mud.

OFFSET WELL PERFORMANCE

Prior to detonation, the s e v e n ga s w ells within a

1-1/4-mile radius ofground zero were shut in for pressurebuild-up study. Sh o r t 1y before detonation, bottom hole

pressure bombs were placed i n three of thes e wells and

surface pressure recording instruments w e r e placed on

three other wells. The cha rts from the se recording instru-men t s only indicated a fluctuation of the stylus at th e

t i m e ground shock reached each instrument and the rateof p r es s u re build-up in each well remained apparentlyunaltered at the time of the detonation and thereafter. No

physical damage was found to have occurred to any of the

field wells or their surface equipment.

RE - ENTRY OPERATIONS

Re-entry drilling operations were initiated in th e em-

placement hole on December 13, following the detonation

on December 10,1967. The program consis ted of drilling

out the sand and cement used to contain the ex plosive in-side the 7-inch casing. Gas was used as the circulating

fluid to a depth of 3300 feet, but was changed to a treatedwater when the cement became sufficiently moist to pre-

clude further ga s drilling. It was determined that w a t e rwas entering the wellbore through the 20-inch s tag e col-lar at a depth of 3550 feet. The rate of influx water was

determined t o be two cubic feet per hour.

At a depth of 3858 feet a six-foot void was encoun-tered a nd circulation was lost. No radioactivity was en-countered. The fluid level was determined to be standing

at a depth of 1750 feet from the surface. D r i 11i n g wa sresumed without the establishment of circulation and on

January 10, 1968 a n i n e-foot void was encountered at adepth of 3907 feet. The bit appear ed to have encountered

metal at a depth of3916 feet and drilling operations werediscontinued. Shortly thereafter radioactive X e n o n gas

was detected at the su rfac e and the wellhead pressure in-creased to 833 psi. The drill pipe utilized to drill downto this depth was stripped out of the hole and 2-1/2-inchtubing was 1 a n d e d at 3792 feet t h r o u g h a productionpacker set at 3786 feet. A diagram of the completed re-

e n t r y wells, GB-ER and GB-ZRS, is shown in Figure 7.Small v o l u m e s of ga s were taken from the well in

order that the gas samples could be collected for labora-

tory analysis. Pressure measurements were made during

the se short flow intervals.

Re-entry drilling into the Gasbuggy No. 2 well was

initiated in June, 1968. During the re-entry operations it

was found that the well could not b e entered to the total

depth due to obstructions in the casing at 3704 feet and

3812 feet. A window was milled in t he ca sing a t 3691feet

and a sidetrack hole was gas-drilled to a new total depth

of 4600 feet. During this re-entry drilling operation, gas

flow measurements were made each time drill pipe con-

nections and t r i p s were made. Production t u b i ng wa slanded in th e uncased hole a t 4224 feet after logging and

su r vey operations were completed. Figure 8illustratesthe gas flow data se cur e d while drilling the post-shotsidetrack hole and also shows a comparison of pre-shot

flow measurements obtained from GB-2.

POST -SHOT TESTING

Production testing on the re-entry emplacement well,

GB-ER, started on June 28, and consisted of producing

the well at a r a t e of five million cub ic feet per day for

si x d ays, s h u t t i n g th e well in one day for bottom hole

pressure and temperature measurement, and resuming the

five m i 11i o n cu bic fe et per day flow rate for five days.The well was then shut in briefly for bottom hole pres sure

and temperature measurement, then reopened at a rate of

0.75 million cubic feet per day for four days with bottom

hole p r essu r e s and temperatures being measured. Thewell was then shut in for pressure build up measurements

w h i c h are sti ll continuing. Figure 9 relates the surfacewellhead and b o t tom hole p r e ssu r e data for this testseries.


6/14


7/14

-t-

--.

3785-+- ---

-----

GASBUGGY NO. I

NATURAL GAS FLOW RATESWHILE CORE DRILLING

3756CSG

3888

Figure 1

3888


8/14

29-4 10

Q ..$+ '"Q

900

800

I TOOhl3eap4

500

000

\ 3880'

\\

\\\

GASBUGGY LOCATION PLAN

SECTION 36-T29 W - R4 W@ - SURFACE LOCATION8 - SHOT DEPTH LOCATION

302I--

GB-E21I,'

Figure 2

N

47'

GB-2

GASBUGGY 1 PRL-SHOT TESTS

30'


9/14


10/14


11/14

GASBUGGY STEMMING

SAN JUAN 29-4 UNIT 10 GASBUGGY EGASBUGGY 1 GASBUGGY 2

Figure 6

POST SHOT RE-ENTRY

GASBUGGY ER GASBUGGY 2RSCmmnt cirrulotcda wrfac. casing49'd 30"-154* bndUc(0r p i pSU Polymercirw~otedcement staging on Z@Production casing

2 7 d 6.5 EUE tubing ot3792'

TR391 PlCTURED CLIFFSShot LEWISpolnt 4240' 0

Figure 7


12/14

IFRUITLANDFORMATION

PICTUREDCLIYFSSANDSTONEtITI

I

SHALELEWIS

GASBUGGY NO. 2 R S

NATURAL GAS FLOW RATES

WHILE DRILLING

m3988

Figure 8


13/14

GASBUGGY ER

_-

20 30 IO 20 30 IO-JUNE-I- JULY #-AUGUST-/968

Figure 9

GASBUGGY ER

I968

Figure 10


14/14

,

POST SHOT TESTS

pI

IO20 30 20_. 30 IOJUNE-^* JULY -I-AUGUST-is68Figure 11

GB-ERGAS ANALYSES WITH FLOW

0 8 - ER GAS ANALYSES100%

cs1360%

&E -)5P

20% CIlRBOlV oloxloE I.0

20 30 2 4 6 0 IO 12 14+JUNE-+I* JULY

pne g9 gasbuggy

Documents