Rapid Assessment of Pattern Waterflooding Uncertainty in a Giant Oil Reservoir

Jones, Alistair; Al-Qabandi, Salman; Reddick, C.; Anderson, S.A.

doi:10.2118/38890-ms

Cited by 11 publications

(4 citation statements)

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“…Oil has been produced from the Mauddud Formation reservoir in the Sabiriyah and Raudhatain fields since the late 1950s, under pressure depletion since there is little natural aquifer support. Offtake rates and predicted recovery factors have remained low under natural depletion and in order to increase offtake, pressure support is now being provided through the implementation of a full-field sea-water injection programme which commenced in late 1999 (Jones et al, 1997).…”

Section: Field Historymentioning

confidence: 99%

Reservoir description of a mid-Cretaceous siliciclastic-carbonate ramp reservoir: Mauddud Formation in the Raudhatain and Sabiriyah fields, North Kuwait

Cross¹,

Goodall²,

Hollis³

et al. 2010

GeoArabia

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The mid-Cretaceous Mauddud Formation is the main producing carbonate reservoir in the Raudhatain and Sabiriyah fields of northern Kuwait. Historical field information and results from waterflood pilots indicate that reservoir performance in these reservoirs is controlled by geological complexity at several scales. A detailed, integrated sedimentological and biostratigraphic investigation of the reservoirs, combined with dynamic reservoir data, have provided an understanding of Mauddud reservoir heterogeneity and of the principle controls on reservoir matrix behaviour. The largely carbonate Mauddud Formation overlies the Upper Burgan Member, a thick succession of fluvio-deltaic deposits, and consists of a diverse suite of carbonate facies deposited in low to high-energy, shallow-marine ramp settings. The basal part of the reservoir comprises mixed carbonate and siliciclastic sediments and reflects the establishment of a carbonate-dominated regime during waning supply of Burgan siliciclastic sediment. This system was eventually drowned and covered by the Wara Formation, a shaly offshore succession that is also the reservoir seal. Sedimentary facies associations and microfossil assemblages within the reservoir are organised in a broadly upward-shallowing succession constructed of several transgressive-regressive cycles, which are defined by prominent, widely-correlatable flooding surfaces. Each cycle exhibits a characteristic internal stacking pattern of minor depositional cycles. Field-wide mapping and interpretation of facies within each cycle reveals a SW to NE, proximal to distal, trend consistent with regional seismic and palaeogeographic interpretations. The high-energy, inner to mid-ramp carbonate succession in the lower portion of the Mauddud reservoir is punctuated by siliciclastic incursions. Abrupt lateral facies changes, thickness variations, and local intra-reservoir erosion surfaces in this section suggest that deposition was influenced by subtle syndepositional tectonism. The upper part of the reservoir, in contrast, lacks significant siliciclastic influence and is made up of widely-correlatable, lower-energy carbonate facies, although local subtle facies variations show that the Raudhatain-Sabiriyah structures continued as palaeohighs during deposition. The contrast in quality between grain-dominated facies at the crests of the two structures and less grainy facies along their flanks was accentuated by carbonate cementation in the water legs of the reservoirs, largely in the form of calcite concretions of variable abundance. Cementation is most pronounced in low-energy wackestone facies, particularly in proximity to flooding surfaces where nodules may be amalgamated to form laterally continuous, cemented layers which are commonly fractured. Another significant, but contrasting, diagenetic modification within the reservoir was the generation of secondary macroporosity through dissolution of aragonitic skeletal components in a shallow to intermediate burial environment. The stratigraphic evolution of the Mauddud reservoir, and its diagenetic overprint, in addition to post-depositional fracturing and faulting, created reservoir heterogeneities, which are critical to reservoir performance; one of the most significant of these is the relationship between horizontal and vertical permeability. Parasequences dominated by high-energy inner ramp grainstones, thin inner ramp rudist-bearing tempestites, and vuggy and fractured rudist floatstones and rudstones constitute thief zones that represent major challenges to reservoir management. In contrast, some cemented layers and flooding surfaces support pressure differentials of up to several hundred pounds/square inch (psi), thus complicating sweep and promoting reservoir compartmentalisation. The strong facies, diagenetic and stratigraphic controls on the distribution of thief zones and intra-reservoir baffles demonstrates how important it is to comprehensively understand reservoir sedimentology and stratigraphy when devising long-term development plans for reservoirs of this deceptively simple character. More recent 3-D seismic data, production surveillance, and horizontal development wells show faults and fractures to be important heterogeneities in both reservoirs. Due to the immaturity of the water flood in the Mauddud reservoirs, the impact of these features on field and well behaviour is as yet unclear, but it is anticipated that the impact of such features on well and field performance will become more pronounced during later development.

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Section: Field Historymentioning

confidence: 99%

Reservoir description of a mid-Cretaceous siliciclastic-carbonate ramp reservoir: Mauddud Formation in the Raudhatain and Sabiriyah fields, North Kuwait

Cross¹,

Goodall²,

Hollis³

et al. 2010

GeoArabia

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“…Papers by Jones 36 , Narayanan 37 and Corre 17 provide examples and more in-depth discussion. The latter reference shows how the techniques can be applied to time-varying responses, such as cumulative production.…”

Section: Tie To Classical Modelsmentioning

confidence: 99%

Improving Investment Decisions Using a Stochastic Integrated Asset Model

Begg¹,

Bratvold²,

Campbell³

2001

Proceedings of SPE Annual Technical Conference and Exhibition

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TX 75083-3836, U.S.A., fax 01-972-952-9435. SummaryThis paper addresses the need for a holistic, integrated approach to assessing the impacts of uncertainty on oil and gas investment decision-making. We argue that this cannot be accomplished effectively by just adding a capability to deal with uncertainty to classical, rigorous models of all the components that contribute to an investment decision evaluation. Further, we suggest that such an approach, if feasible, is not desirable. Instead, we propose the concept of a Stochastic Integrated Asset Model (SIAM) embedded in a decision support system. This approach involves trading-off some technical rigor for a more complete and accurate assessment of the impacts of uncertainty on the investment decision-making process. The main elements of the system are: simplified component models for each domain; Monte Carlo simulation engine; modeling language for customization, incorporation of interdependencies between components, implementation of decision logic and updating information as a result of learning. We illustrate how such a system identifies which uncertainties impact the decision the most; values the acquisition of information (data, technical analysis) and encourages flexibility in go-forward plans to mitigate and/or exploit uncertainties. Further applications are to the optimization of development plans, real options valuation and the generation of consistent, risked cash flows for input to portfolio analysis. We believe that application of such a system results in a true value-driven focus to the work of multi-disciplinary asset teams through its ability to integrate the technical and business aspects of decisions.

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Section: Generating Simple Surrogatesmentioning

confidence: 99%

Improving Investment Decisions Using a Stochastic Integrated Asset Model

Begg

Bratvold

Campbell

2001

SPE Annual Technical Conference and Exhibition

View full text Add to dashboard Cite

This paper addresses the need for a holistic, integrated approach to assessing the impacts of uncertainty on oil and gas investment decision-making. We argue that this cannot be accomplished effectively by just adding a capability to deal with uncertainty to classical, rigorous models of all the components that contribute to an investment decision evaluation. Further, we suggest that such an approach, if feasible, is not desirable. Instead, we propose the concept of a Stochastic Integrated Asset Model (SIAM) embedded in a decision support system. This approach involves trading-off some technical rigor for a more complete and accurate assessment of the impacts of uncertainty on the investment decision-making process. The main elements of the system are: simplified component models for each domain; Monte Carlo simulation engine; modeling language for customization, incorporation of interdependencies between components, implementation of decision logic and updating information as a result of learning. We illustrate how such a system identifies which uncertainties impact the decision the most; values the acquisition of information (data, technical analysis) and encourages flexibility in go-forward plans to mitigate and/or exploit uncertainties. Further applications are to the optimization of development plans, real options valuation and the generation of consistent, risked cash flows for input to portfolio analysis. We believe that application of such a system results in a true value-driven focus to the work of multidisciplinary asset teams through its ability to integrate the technical and business aspects of decisions.

show abstract

Rapid Assessment of Pattern Waterflooding Uncertainty in a Giant Oil Reservoir

Cited by 11 publications

References 0 publications

Reservoir description of a mid-Cretaceous siliciclastic-carbonate ramp reservoir: Mauddud Formation in the Raudhatain and Sabiriyah fields, North Kuwait

Reservoir description of a mid-Cretaceous siliciclastic-carbonate ramp reservoir: Mauddud Formation in the Raudhatain and Sabiriyah fields, North Kuwait

Improving Investment Decisions Using a Stochastic Integrated Asset Model

Improving Investment Decisions Using a Stochastic Integrated Asset Model

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