Recovery Mechanisms and Oil Recovery From a Tight, Fractured Basement Reservoir, Yemen

Legrand, Nicolas; Kok, Joop Hendrik De; Neff, Pascale; Clemens, Torsten

doi:10.2118/133086-ms

Cited by 5 publications

(1 citation statement)

References 29 publications

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“…et al [4] proposed the relationship between the degree of compaction, the decrease of porosity based on the linear pore elasticity theory of small strain, and proposed that decrease in permeability of sandstone near the elastic range is primarily dependent on the increase in average effective stress. Legrand, N. et al [5] studied the production mechanism of tight oil in Yemen, and the crude oil flow mainly depended on matrix microfractures and fracture channels. The crude oil flows through the matrix microfractures into the fracture channel and then is produced.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Flowback Behavior for Multi-Fractured Horizontal Wells in Gulong Shale Oil Reservoir Based on Numerical Simulation

Yu,

Wu,

Niu

et al. 2024

Preprint

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Multi-stage hydraulic fracturing with horizontal well technology has been widely used in shale oil reservoir. After hydraulic fracturing, hydraulic fractures and opened beddings are intertwined, which result in a complex fracture network. As well as the migration of multi-phase fluids during fracturing and soaking processes, which lead to complex flowback performance, and brings dif-ficulty to productivity evaluation and flowback strategies optimization. In this paper, taking the Daqing Gulong shale reservoir as an example, a numerical model for flowback period, which considered oil-water-gas three-phase flow and orthogonal fracture network has been established. The characteristics and influencing factors of flowback performance have been deeply studied, and the flowback modes of shale oil are reasonably optimized. Factors such as PTPG (pseu-do-threshold pressure gradient), opened bedding stress sensitivity, opened bedding permeability and matrix permeability have obvious effects on the flowback performance, resulting in signifi-cant variations in production peaks, high yield periods, and decline rates. In addition, three flowback modes are distinguished based on the rate at which the BHP (bottom hole pressure) drops. These correspond to three types of choke modes. Based on the result of numerical model, three flowback modes are optimized and the impacts of different flowback modes on shale oil flowback are clarified. This study is particularly important for understanding the performance of shale oil flowback and guiding the efficient exploitation of shale oil.

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Section: Introductionmentioning

confidence: 99%

Investigation of Flowback Behavior for Multi-Fractured Horizontal Wells in Gulong Shale Oil Reservoir Based on Numerical Simulation

Yu,

Wu,

Niu

et al. 2024

Preprint

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Petroleum Geology and Hydrocarbon Potential of the Guban Basin, Northern Somaliland

Ali

2015

Journal of Petroleum Geology

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The Guban Basin is a NW-SE trending Mesozoic-Tertiary rift basin located in northern Somaliland (NW Somalia) at the southern coast of the Gulf of Aden. Only seven exploration wells have been drilled in the basin, making it one of the least explored basins in the Horn of Africa --southern Arabia region. Most of these wells encountered source, reservoir and seal rocks. However, the wells were based on poorly understood subsurface geology and were located in complex structural areas.The Guban Basin is composed of a series of on-and offshore sub-basins which cover areas of 100s to 1000s of sq. km and which contain more than 3000 m of sedimentary section. Seismic, gravity, well, outcrop and geochemical data are used in this study to investigate the petroleum systems in the basin. The basin contains mature source rocks with adequate levels of organic carbon together with a variety of reservoir rocks. The principal exploration play is the Mesozoic petroleum system with mature source rocks (Upper Jurassic Gahodleh and Daghani shales) and reservoirs of Upper Jurassic to Miocene age. Maturity data suggest that maximum maturity was achieved prior to Oligocene rift-associated uplift and unroofing. Renewed charge may have commenced during post-Oligocene-Miocene rifting as a result of the increased heat flows and the increased depth of burial of the Upper Jurassic source rocks in localised depocentres. The syn-rift Oligocene-Miocene acts as a secondary objective owing to its low maturity except possibly in localised offshore sub-basins. Seals include various shale intervals some of which are also source rocks, and the Lower Eocene evaporites of the Taleh Anhydrite constitute an effective regional seal. Traps are provided by drag and rollover anticlines associated with tilted fault blocks. However, basaltic volcanism and trap breaching as a consequence of the Afar plume and Oligocene-Miocene rifting of the Gulf of Aden cause considerable exploration risk in the Guban Basin.

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An Integrated History Matching Approach of a Fractured Basement Reservoir - Block S2, Yemen

2012

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This work addresses the challenging task of history matching a fractured basement reservoir. Habban field, south-western part of Yemen, produces from two different horizons: the Kuhlan sandstone overlaying the fractured basement. The fractured basement reservoir is characterized by two types of fracturing: background fractures with very low effective permeability of less than 0.001mD and fracture corridors with an effective permeability ranging from 0.01 up to 10 mD, and a total porosity of 1.3% only. Two sets of fracture corridors, with N-S and NW-SE mean orientation, contribute to production whereas background fractures act as storage feeding in those corridors. The large contrast in properties between Kuhlan and Basement adds-on further challenges: Kuhlan possesses good reservoir properties but moderate storage (~10m thick), whereas fractured basement has extremely poor reservoir properties but significant storage (~700m thick). Habban field has produced since end 2006 by depletion through 30 slanted wells. To optimally assess different production strategies, a simulation model was built. Dynamic data (MDT, PLT, BHP, production rates) were used to constrain the dynamic model on well by well basis. Due to this extremely challenging setting, a very high focus was put on a history matching process that integrates geology and reservoir simulation work to result into an enhanced understanding of field mechanisms. One main conclusion of this integrated history matching approach is that water comes to wells from neighborhood formations through main faults, explaining then the erratic water production (no crest to flank correlation). Second highlight concerns the major contribution of N-S main fractures. Finally understanding of the communication mechanism between basement and Kuhlan was enhanced, showing that despite basement poor properties, basement oil feeds in Kuhlan, as Kuhlan is produced. This synergized understanding of Habban mechanisms is a clear milestone for further well location planning and oil recovery optimization under uncertainty.

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Recovery Mechanisms and Oil Recovery From a Tight, Fractured Basement Reservoir, Yemen

Cited by 5 publications

References 29 publications

Investigation of Flowback Behavior for Multi-Fractured Horizontal Wells in Gulong Shale Oil Reservoir Based on Numerical Simulation

Investigation of Flowback Behavior for Multi-Fractured Horizontal Wells in Gulong Shale Oil Reservoir Based on Numerical Simulation

Petroleum Geology and Hydrocarbon Potential of the Guban Basin, Northern Somaliland

An Integrated History Matching Approach of a Fractured Basement Reservoir - Block S2, Yemen

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