Overestimation of Original Gas in Place in Water-Drive Gas Reservoirs Due to a Misleading Linear p/z Plot

Elahmady, Mohamed; Wattenbarger, R.A.; Pham, Tai

doi:10.2118/02-11-01

Cited by 3 publications

(4 citation statements)

References 4 publications

(4 reference statements)

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“…The second way is that sands with unified gas-water interface in different substrata are linked vertically at individual well in general, which is called sand link point. This kind of wells exists almost in the main sands, especially in Ng 1+2 [11][12][13] . Judgment of connectedness for this kind of multi-layer sands is difficult, because it is based on data of well testing basically.…”

Section: Reservoir Connectednessmentioning

confidence: 99%

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Revitalization of Gas Field Applying Reservoir Characterization Techniques

Sheng

Ding²,

Li³

2003

Canadian International Petroleum Conference

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Gudao shallow gas field has been in later production period. In order to improve the development results, researches of reservoir characterization and enhancing gas recovery were launched in 1997. Utilizing technical measures including geology, geophysical, logging, gas reservoir engineering and stratigraphic correlation etc., original gas in place (OGIP) is recalculated and evaluated. On the basis of production characteristics analysis, distribution of remaining gas is made clear, and potential targets are put forward. The major results are as follows. 1. Substrata are re-divided utilizing sand tracing technique and secondary logging interpretation. 2. Cognition of some gas sands being not connected mutually is turned via stratigraphic re-correlation, thus contradictions of unbalanced reserves-production relationship and lower formation pressure of new wells than normal pressure are solved. 3. Change rules of output and pressure for various kinds of reservoirs are investigated, and main factors influencing recovery efficiency are analyzed and respective ways for enhancing recovery efficiency are brought forward sequentially. 4. OGIP is recalculated using pressure drop method (p/z-Gp) to verify results of volumetric method further, which can explain why recovery efficiencies of some reservoirs exceeded 100% before. 5. Based on break-even analysis, economic limit reserves for different kinds of reservoirs are computed, and overall adjustment plan is submitted, in which 12 wells have been brought on stream with gas rate of 107 ¥ 10 3 m 3 /d.Incremental producing reserves in place are 508 ¥ 10 6 m 3 with recoverable reserves 305 ¥ 10 6 m 3 , and favorable economic benefit has been seen with predictable production value about RMB 1,700 million Yuan. Thirty-five backup reservoirs are found as well, which provides dependable foundation for the future, and PETROLEUM SOCIETY CANADIAN INSTITUTE OF MINING, METALLURGY & PETROLEUM2 overall recovery efficiency predicted could be advanced for more than 5% and gas production decrease has been relieved. The results could provide certain directive meanings for gas fields of similar type.

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Section: Reservoir Connectednessmentioning

confidence: 99%

“…12,13 For OGIP of single reservoir is small, only one well is drilled on one reservoir in general, thus influences of well pattern and well space does not exist. Under conditions of not sand production, rate of gas production has little influence on recovery factor for gas reservoir.…”

Section: Production Factorsmentioning

confidence: 99%

Revitalization of Gas Field Applying Reservoir Characterization Techniques

Sheng

Ding²,

Li³

2003

Canadian International Petroleum Conference

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“…Due to the high requirements and difficulty in testing the compressibility of the reservoir rock in abnormal pressure gas reservoirs, the experimental test results of the rock compressibility under abnormal pressure were not reported, − and this perhaps the reason for the misunderstanding of abnormal pressure gas reservoirs. , This research aims to accurately determine the rock compressibility and correctly understand the development characteristics of abnormal pressure gas reservoirs. In this research, a series of experiments for developing abnormal pressure gas reservoirs were designed to accurately obtain the compressibility of formation rocks under abnormal pressure conditions.…”

Section: Introductionmentioning

confidence: 99%

Compressibility of Abnormal Pressure Gas Reservoirs and Its Effect on Reserves

Zhang

Gao

2021

ACS Omega

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The compressibility of abnormal pressure gas reservoirs is hard to test, and the interpretation is confusing, leading to many misunderstandings in the current understanding of abnormal pressure gas reservoirs. In this research, a highpressure experimental system was designed, and a series of highpressure compressibility tests of pure water, nitrogen, and rocks under different water saturations were carried out. Then, the effective compressibility of gas reservoirs was calculated; the effect of water saturation on abnormal pressure gas reservoirs and the dynamic prediction was studied. The results show that the compressibilities of water and rock are effectively constant values over the range examined, while the compressibility of gas decreases exponentially with the increase in pressure. The effective compressibility of the stratum increases with the rise of water saturation. The theory of stress and strain of rock mechanics also shows that the rock compressibility is determined by Young's modulus, Poisson's ratio, and porosity and has no connection with the formation pressure. With the increase in water saturation, the swelling degree of the production indicator curve of the simulation experiment becomes larger and larger. After introducing the effective compressibility of the stratum into the gas−water material balance equation, the gas reserves predicted by the revised production indicator curve are the same as the original reserves. The research results have important guiding significance for the efficient development of gas reservoirs.

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“…Author is with the Petroleum engineering Department, Pertamina University, Jakarta, Indonesia (phone: +62 812 2287 3130, e-mail: agus.prama@gmail.com). 4 Putu Suarsana. Author is with Magister Petroleum Engineering Department, Trisakti University, Jakarta, Indonesia, (phone: +62 811889229, e-mail: ips3150@yahoo.com) 5 Anis N Utami.…”

Section: Introductionmentioning

confidence: 99%

Integrated Reservoir Study to Optimize Gas Production of Water Drive Gas Reservoir Case Study: Lower Menggala Gas Field

Widiantoro¹,

Pramana

Suarsana

et al. 2018

ins

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Production optimization in mature field water drive gas reservoir is not easy especially when water already breakthrough in producing wells. An integrated reservoir study is needed to get reliable strategy to optimize production of water drive gas reservoir. This research presents the integrated reservoir study of Lower Menggala (LM) Gas Field which is located Central Sumatera Basin, Riau Province. LM had been produced since 1997, current RF are 55%, which is quite high for water drive gas reservoir. The current gas rate production is about 1.97 MMscfd with high water production around 4250 BWPD, consequently some of wells suffered liquid loading problem This research comprises of well performance analysis, estimate OGIP, aquifer strength of the reservoir by using conventional material balance method and modern production analysis method then conduct dynamic reservoir simulation to identify the best strategy to optimize gas production. Economic analysis also be performed to guide in making decision which scenario will be selected. DST analysis on DC-01 well defined reservoir parameter, boundary and deliverability which are P*= 2520 psia, k= 229 mD, Total skin= 8, detected sealing fault with distance 175 m, and AOF 45 MMscfd. Conventional material balance method gave OGIP 22.7 BScf, aquifer strength 34 B/D/Psi, whereas modern production analysis estimated OGIP 22.35 BScf, aquifer strength 34 B/D/psi. Those two method shows good consistency with OGIP volumetric calculation with discrepancy OGIP value +/- 1%. Six (6) scenario of production optimization has been analyzed, the result shows that work over in two wells and drilling of 1 infill well (case 6) achieve gas recovery factor up to 75.2%, minimal water production and attractive economic result

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Overestimation of Original Gas in Place in Water-Drive Gas Reservoirs Due to a Misleading Linear p/z Plot

Cited by 3 publications

References 4 publications

Revitalization of Gas Field Applying Reservoir Characterization Techniques

Revitalization of Gas Field Applying Reservoir Characterization Techniques

Compressibility of Abnormal Pressure Gas Reservoirs and Its Effect on Reserves

Integrated Reservoir Study to Optimize Gas Production of Water Drive Gas Reservoir Case Study: Lower Menggala Gas Field

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