Log Determination of Residual Oil Saturation in the Mauddud Zone, Bahrain Field

Wolff, Martin; Al-Jalahma, A.M.; Hook, Peter

doi:10.2118/25648-ms

Cited by 11 publications

(3 citation statements)

References 10 publications

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“…In particular, the low-permeability, microporous matrix properties of these Mauddud reservoirs are not only similar to Mauddud reservoirs elsewhere, but to many other early and mid-Cretaceous reservoirs in the Thamama, Bangestan and Wasia Groups and their equivalents in the UAE (O'Hanlon et al, 1996;Grötsch et al, 1998), Bahrain (Shehabi and Kollourii, 1987;Wolf et al, 1993), Oman (Harris and Frost, 1984); Saudi Arabia, Iraq and Iran. The upper, shallowest-water parts of shoaling-upwards depositional cycles commonly contain distinctive, coarse-grained, vuggy rudistid rudstones with significantly higher measured permeabilities than the background matrix and strongly contrasting 47 relative permeability characteristics (cf.…”

Section: Application To Other Middle Eastern Reservoirsmentioning

confidence: 66%

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: Application To Other Middle Eastern Reservoirsmentioning

confidence: 66%

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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“…5 The gas injection is very effective in most parts of the reservoir, except the northern and southern flanks, where the water drive dominates. Laboratory studies and cased-hole logs, 6,7 show that large quantity of residual oil (S or of nearly 50 %) will be left in such a system either by gas flooding or by water flooding (Figure: 8). In such system, DEPTH FT 1:320…”

Section: Oil Wet Systemmentioning

confidence: 99%

Reserves Estimation and Classification Challenges in a Mature Oil Field

Zubari¹,

Kumar²

2007

Proceedings of SPE Middle East Oil and Gas Show and Conference

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractEstimation of hydrocarbon reserves is governed by natural, technological and economic factors. Re-estimations and reviews continue almost till the end of exploitation in many instances. Estimation of oil reserves, when a field is in its initial stages of development is a relatively easy task. The estimation will not invite critical or close scrutiny, as the oil production at that stage is far lower than the reserves calculated. However as the field matures and the cumulative oil production approaches the estimated value of reserves, the accuracy in the estimation of reserves becomes crucial and more important. Also the estimation process itself is a challenging task, in the light of uncovering geological complexities and reservoir dynamics during the development and the exploitation methods employed to produce the oil.

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“…De acordo com Wolff et al (1993), mostrou-se eficiente no mapeamento e distinção do óleo remanescente do gás presente no reservatório, apresentando também bons resultados quando utilizadas na calibração de demais poços. Entretanto, algumas considerações foram feitas no que diz respeito às condições necessárias para a utilização em reservatórios.…”

Section: Histórico De Utilização Da Ferramenta E Trabalhos Relacionadosunclassified

Tecnicas geoestatisticas aplicadas na modelagem da saturação de oleo

Zanão¹

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Degree).Cased well logging with tools which quantify the water saturation had been done in the Study Field, located on Recôncavo Basin, considered mature and with reminiscent hydrocarbonates storage in the Sergi Formation. The geostatistical techniques of ordinary kriging and kriging with external drift had been used to the studied field for porosity and water saturation of development model. The results of the modeling of water saturation variable in steps of time allowed to characterized the evolution of the water saturation in the field and the identification of the remaining oil portions. With information models of petrophysics and the fluids saturation , the oil volume calculus for the three temporal intervals analyzed had been done. Values had been obtained which allowed proving the dynamic of Sw variable along the years and verifying the reminiscent oil in the reservoir.

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Log Determination of Residual Oil Saturation in the Mauddud Zone, Bahrain Field

Cited by 11 publications

References 10 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

Reserves Estimation and Classification Challenges in a Mature Oil Field

Tecnicas geoestatisticas aplicadas na modelagem da saturação de oleo

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