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Page 1: Ghawar Still No 1
Page 2: Ghawar Still No 1

Left top: A July 25, 1948, lab report strongly indicated the presence of hydrocarbons at ‘Ain Dar. Left middle: A June 12, 1951, flow-test report on Ghawar’s first well, at ‘Ain Dar, was very promising. Left bottom: Legendary Bedouin guide Khamis bin Rimthan was instrumental in guiding Aramco geologists to potential well sites throughout the Eastern Province. Above: a map showing the location of Ghawar “discovery” wells west of the Arabian Gulf.

Expo 2010, Shanghai 51

62-year-old super-giant Ghawaroil field as productive as everWritten by Brett Fischbuch and Tom Keith

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The debut discoveries, following the signing of anexploration concession agreement between Saudi Arabiaand Standard Oil Of California (Socal) in 1933, wereat Dammam (1938), Abu Hadriyah (March 1940) andAbqaiq (December 1940).

These successes led in less thana decade to the astounding real-ization that a number of appar-ently independent, commerciallyviable oil fields were, in fact, allpart of one mind-bending mega-field — Ghawar.

Ghawar is divided into fiveareas, discovered individually:’Ain Dar (1948), Haradh (1949— located in the southernmostpart of the field), ‘Uthmaniyah(1951), Shedgum (1952) andHawiyah (1953).

The giant reservoir is 280 kilo-meters long and 40 km wide,encompassing 1.3 million acres.Saudi Aramco continues topump about 5 million barrelsof Arabian Light crude oil fromGhawar reservoirs every day. Italso pumps 2.5 billion cubic feetper day (cfd) of natural gas fromthe field in association with theproduction of oil, and another 4billion cfd of non-associated gas,produced from independent gasreservoirs beneath but not part ofGhawar’s oil-bearing formations.

So, by all measures, Ghawar— the “crown jewel” for SaudiAramco and the Kingdom —is an awesome asset.

Ghawar has all the right stuffto be a super producer: high po-rosity of its reservoir rock, whichmeans there’s an abundance of

rock pores, or spaces, for holding oil; high permeabil-ity, meaning many natural channels allowing oil to flowthrough the rock; valuable light rather than heavy oil; andhigh recovery potential.

The original realization of Ghawar’s existence wasa kind of educated hunch.

In 1940, while the Abqaiqprospect was being drilled, ayoung geologist — Ernie Berg— was spending his second fieldseason mapping adjacent quad-rangles on the edge of the greatRub‘ Al-Khali desert, or “EmptyQuarter.” Berg mapped the dryriver bed known as Wadi Sahabain the Haradh area and noticedthat it took a sharp turn to thesouth from its normal east-westcourse for no reason apparent tothe naked eye.

After measuring and plot-ting a large enough area to seea trend, it became apparentthat the wadi was diverted bya broad, low-relief dome, thesurface expression of a muchlarger subsurface dome or an-ticline. Aramco geologist MaxSteineke, who was the drivingforce behind the company’s firstcommercial discovery two yearsearlier at Well No. 7 in Dam-mam, came into camp the nextday and agreed with Berg thatthe Haradh structure was poten-tially significant.

In fact, it turned out thatBerg’s map was the first to delin-eate a structure in the Ghawarfield and was therefore whatgeologists would call the “dis-covery map” for that field. With

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Above: Saudi Arabia’s King Abdulaziz Al Saud ushered in a transformational era by fully sup-porting the search for oil in his Kingdom starting in 1933. Top left: Ernie Berg, at right, with fel-low geologist Tom Barger in the 1930s, is credited with discovering the desert outcrops that hinted at giant Ghawar’s existence. Middle left: ’Ain Dar No. 1, an early pro-duction well. Bottom left: a desert exploration party in the Ghawar area in the 1940s.

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Legendary Aramco geologistMax Steineke, above, backedthe intuitions of fellow geolo-gist Ernie Berg that ultimatelyproved well-founded, as a seriesof seemingly independent fieldsproved to be one giant field,Ghawar. Top right and middle:Aerial views of ‘Udhailiyah, thenthe new base for South Ghawarfield operations, 1956. Bottomright: the Ghawar field’s Hawi-yah Gas Plant, 1999.

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the onset of World War II, the difficulties of getting suppliesand the loss of men to the war effort, wildcat drilling wassuspended. However, a shallow-drilling campaign designedto confirm geologic structures based on Berg’s and other ge-ologists’ maps was continued. The shallow drilling confirmedBerg’s subsurface anticline at Haradh and was continuednorthward, confirming a continuous anticline stretching fromHaradh to ’Ain Dar and Shedgum. This anticline was dubbedthe En Nala anticline, meaning “The Slippers.”

After World War II and with the resumption of drilling,the most obvious location to resume wildcat drilling wasthe ’Ain Dar structure because of its proximity to producingfacilities at Abqaiq. ’Ain Dar No. 1 was completed in July1948 and put on production in early 1951 at an extraordi-nary rate of 15,600 barrels per day (bpd) of dry oil, mean-ing without water contamination. ’Ain Dar No. 1 was asignificant discovery for Aramco, but nobody knew howsignificant it would become.

Although a number of structures with apparent closurehad been delineated, and at least ’Ain Dar had proven to beoil-filled, nobody openly suggested that the En Nala anti-cline would prove to be one continuous field. Aramco engi-neers wanted to drill a step-out well, ’Ain Dar No. 2, about12 km south of ’Ain Dar No. 1, but Steineke argued thatthe next well should be 185 km to the south on the Haradhstructure first mappedby Ernie Berg nineyears earlier. Steinekeprevailed.

Haradh No. 1 wasa successful wildcatdrilled in 1949. Nextcame ‘UthmaniyahNo. 1, which wasdrilled in 1951. TheShedgum No. 1discovery well wasdrilled in 1952, fol-lowed by HawiyahNo. 1 in 1953. ’AinDar No. 1, Shedgum

No. 1, Haradh No. 1 and Hawiyah No. 1 are still produc-ing today.

These discoveries pointed toward the existence of onecontinuous reservoir with a common oil/water contact,which was designated as Ghawar Field in 1952.

Ghawar — the Bedouin originally called the pasturagearea “El Ghawar” — remains the largest single oil field onEarth. Not only is Saudi Aramco getting most of its dailyoil production from Ghawar but also most of its daily raw-gas feed.

The field’s production reached a zenith of 5.7 millionbpd by 1981 — a world record for continuous productionin a single field — but output was reduced later that decadedue to declining demand. Still, the field’s current, sustained5 million bpd output is unrivaled.

Since its discovery, enormous Ghawar has kept oil ex-perts on their toes. In mid-2007, the Ghawar IntegratedAssessment and New Technology (GIANT) team, an inter-departmental group working on a long-term, visionaryendeavor to better understand and characterize the oil field,came across an interesting finding while looking at waysto maximize the reservoir’s oil recovery percentage. Theresearchers found an extensive micro-pore system of hiddenpassages in carbonate rock, where a significant percentageof unrecovered oil resides. Today, the GIANT team is ana-

lyzing this newfoundpotential and find-ing ways to tap intothe as-yet untappedworld below.

Chart above shows the accumulative oil production over the years ofGhawar’s five discovery wells.

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After World War II and withthe resumption of drilling,the most obvious location toresume wildcat drilling was the’Ain Dar structure because ofits proximity to producing facili-ties at Abqaiq. ’Ain Dar No. 1was drilled in 1948 and flowedoil to the surface during drillstemtesting.

’Ain Dar No. 1 was put on pro-duction in early 1951 at anextraordinary oil rate of 15,600barrels per day (bpd) — and is stillproducing today more than 57 yearslater, with the original well casingsand with the aid of best-in-class res-ervoir management practices.

The well, amazingly, produced“dry oil” for 49 years, before pro-ducing its first water in 1999. Overthe years, this magnificent well hasproduced 152 million barrels of oiland is still producing 2,100 bpdin 2008.

In 1949 Aramco engineers wantedto drill a step-out well, ’Ain DarNo. 2, about 12 km to the southof ’Ain Dar 1; instead, a secondwildcat was drilled 185 km to thesouth at Haradh. At that time,no one openly suggested that the En Nala anticlinewould prove to be one continuous field. This pos-sibility became very real when the Haradh No. 1wildcat struck oil in 1949.

However, because Haradh well was nearly200 km south of ’Ain Dar production facili-ties and therefore impractical to produce atthe time, Aramco had to wait 15 years tobring it on-stream. In 1964, Haradh No. 1was finally put on production at an oil rateof 6,400 bpd. The well was shut in duringthe mid-1980s due to low demand butresumed production in 1990 at 6,700 bpdof dry oil, after acid stimulation. HaradhNo. 1 has produced more than 24 mil-lion barrels of oil in its career, and con-tinues to produce in 2008 at an oil rateof 2,300 bpd with a watercut of only1 percent.

‘Uthmaniyah No. 1 was important in

establishing that the En Nala anticline was oil-filledbetween ’Ain Dar and Haradh. This wildcat wellwas drilled in 1951 and tested initially at 9,200 bpd.As with the other Ghawar wells, oil gravity was inthe range of 33 degrees API (Arabian Light Crude).

‘Uthmaniyah No. 1 wasbrought onstream in 1956and produced at an oil rateof 11,300 bpd in its firstyear. Located on the easternflank of ‘Uthmaniyah, thiswell was the first of thediscovery wells to employ awater shutoff to extend dryoil production. This dis-covery well has producedmore than 20 million bar-rels of oil.

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The Shedgum No. 1 discovery well was drilledin 1952 to delineate the En Nala anticline tothe east of ’Ain Dar. The well struck oil inthe Arab-D carbonate and was later broughton-stream in 1954 at an outstanding oil pro-duction rate of 12,400 bpd, comparable to’Ain Dar No. 1.

In 1968 the wellbore rock matrix wasacidized to improve the flow of oil fromthe carbonate formation. In 1989 linerswere run across the open hole to proac-tively address future water encroachment.

Recently, the oil production ratewas enhanced greatly for ShedgumNo. 1 by recompleting the well with ahorizontal sidetrack complemented byinflow control device (ICD) technology. Notonly was the oil rate increased from about1,000 bpd to over 3,700 bpd, the watercuthas also been lowered significantly.

Shedgum No. 1 has produced more than98 million barrels of oil over the last 55years, and the application of new technolo-gies will keep the well producing for years tocome.

The final discovery well was Hawiyah No.1, which confirmed that Ghawar held oilbetween ‘Uthmaniyah and Haradh. Drillingwas completed in 1953, and the well cameon-stream in 1966 at 4,800 bpd of dry oil.

The well received an acid stimulationtreatment in 1977, with subsequent pro-duction of 7,600 bpd. Hawiyah No. 1has produced 51 million barrels of oil,and continues to produce today at 4,600bpd.

Since the discovery of the Ghawar fieldin 1948, Saudi Aramco has implementedbest-in-class field management practicesand leading technologies that haveevolved over the years. As a result,Ghawar’s “magnificent five” discovery

wells have demonstrated extraordinaryperformance with extended lifecycles andoutstanding oil recovery.

One of the first reservoir managementinitiatives was gas re-injection in ’Ain Dar.In 1958, King Sa’ud Ibn ‘Abd al-Aziz inau-gurated the Gas Injection facilities in ’AinDar. The primary purpose of this programwas to re-inject produced gas to sustain res-ervoir pressure. Gas injection commenced in1959 and continued for 20 years.

Water injection began in Ghawar in 1964to provide additional pressure support (i.e.

maintaining reservoir capacity to push oilto the surface). This technology, known assecondary recovery, provided a stepwise im-provement in pressure support, and beganthe displacement of oil from the outer edgesof the Ghawar field toward the centralregions to sustain oil production, as demon-strated by the phenomenal performance ofthe discovery wells.

In 1995, a comprehensive 3-D seismiccampaign was conducted across the Gha-war field. The seismic profiles providedvital information on reservoir structure anddistribution of fractures, guiding develop-ment and re-completions across Ghawar.This information, for example, was usedin guiding the placement of the horizontal

well trajectory for ShedgumNo. 1.

The Ghawar discoverywells are still producing todaywith their original well casings.This highlights the outstandingquality of workmanship andmaterials. Combined, the fiveGhawar discovery wells haveproduced nearly 350 millionbarrels of oil.

The discovery wells will con-tinue producing oil, and at theappropriate time Saudi Aramcowill apply the latest best-in-classtechnologies to further extendproducing life and curtail waterproduction.

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(1) 1948 Letter to His Excellency Finance Minister Abdullah Sulaiman reporting that wildcat well ’Ain Dar No. 1 successfully flowed oil to the surface. (2 through 5) Original well completion drawings for Haradh No. 1, ‘Uthmaniyah No. 1, Shedgum No. 1 and Hawiyah No. 1. (6) The original Hawiyah No. 1 well resistivity log showing large oil column.

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