Structural and petrophysical controls on the remaining fluid distribution in the reservoirs of Gharif Formation before abandonment

Taura, Usman; Al-Dhuhli, Hajar; Rudyk, Svetlana Nikolayevna

doi:10.1007/s12665-022-10626-z

Cited by 2 publications

(10 citation statements)

References 17 publications

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“…Fissures were detected in core samples resulting in permeabilities of up to 200 mD. More details about Gharif formation and the Haushi reservoirs in this field can be found in [14,15].…”

Section: Geologic Setting Of the Oil Fieldmentioning

confidence: 95%

“…Porosity (Phi) was calculated using density log, which provided a good match with the core date, and permeability was calculated using correlations with porosity, as described in Ref. [14]. Water saturation was calculated using Archie and Simandoux equations for comparison.…”

Section: Methodsmentioning

confidence: 99%

“…Sensitivity analyses for porosity and permeability cut-offs and other main uncertainties such as oil-water contact were also conducted. Details of the modelling and simulation procedures can be found in [14,15].…”

Section: Methodsmentioning

confidence: 99%

“…The factor of similar horizontal and vertical permeabilities can play a substantial role in fast water breakthroughs. In this study, we focused on the influence of permeability anisotropy on the simulation results while the details of the simulation procedure can be found in Ref [14,15].…”

Section: Influence Of Kv/kh On the Production Curvesmentioning

confidence: 99%

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Matching of Water Breakthrough in Low Resistivity Oil Reservoir Using Permeability Anisotropy

Rudyk,

Al Musalhi,

Taura

et al. 2024

Preprint

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Uncertainties in initial water saturation and early water breakthroughs of un-known sources and paths, which occurred in the low resistivity Lower Haushi sand-stone (LHS) reservoir at the beginning of oil production, imply that the bypassed oil can yet remain in the reservoir. In addition, the upper part of LHS is a tight oil reser-voir, which can still contain a significant amount of unrecovered oil. This opens the opportunity to produce the remaining oil instead of abandoning this reservoir. Low resistivity can exaggerate water saturation, leading to misinterpretation and premature water flooding due to inadequate oil-water contrast. Our analysis revealed a correlation between low resistivity and robust porous network connectivity, along-side elevated formation water salinity in highly porous layers. In regions of high po-rosity, sufficient oil-water contrast facilitates precise water saturation determination, affirming oil presence in all wells. However, within tight oil zones, near-complete wa-ter saturation contradicts actual oil presence. Factors contributing to saturation un-certainty and water breakthroughs were reassessed. Utilizing a 1:1 verti-cal-to-horizontal permeability ratio derived from core data enhanced simulation alignment with water production rates. Investigation into the impact of relative per-meabilities on water production was conducted. Water saturation maps were gener-ated to pinpoint remaining oil reserves. Depletion around wells is evident in lower po-rous regions, while oil persists across the entire tight reservoir, notably in two unex-plored sections.

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“…Fissures were detected in core samples resulting in permeabilities of up to 200 mD. More details about Gharif formation and the Haushi reservoirs in this field can be found in [14,15].…”

Section: Geologic Setting Of the Oil Fieldmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Influence Of Kv/kh On the Production Curvesmentioning

confidence: 99%

See 2 more Smart Citations

Matching of Water Breakthrough in Low Resistivity Oil Reservoir Using Permeability Anisotropy

Rudyk,

Al Musalhi,

Taura

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…Fissures were detected in core samples, resulting in permeabilities of up to 200 mD. More details about the Gharif Formation and the Haushi reservoirs in this field can be found in [14,15].…”

Section: Geologic Setting Of the Oil Fieldmentioning

confidence: 96%

Matching of Water Breakthroughs in a Low-Resistivity Oil Reservoir Using Permeability Anisotropy

Rudyk,

Al-Musalhi,

Taura

et al. 2024

Applied Sciences

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In a mature middle and lower Gharif field in Oman, uncertainties surrounding initial water saturation and early water breakthroughs of unknown sources and paths suggest the presence of significant bypassed oil. In order to determine the areas with remaining oil, petrophysical and logging data of seven wells were processed using Techlog software and imported into Petrel software for modelling and simulation. Porosity was calculated using the Electric Propagation Time log and was utilized to evaluate the presence of oil, particularly in the upper tight zone of the formation. Despite the low resistivity readings in the highly porous layers, caused by good network connectivity and high formation water salinity, the resistivity contrast was sufficient to differentiate them from the oil zone. However, the calculated water saturation (Sw) in the tight top oil zone was high, consistent with the observed water production in the field. To improve the match between production data and simulation results, sensitivity analyses were conducted on various permeability anisotropy and relative permeability values within the model. The analyses showed that core-derived permeability anisotropy (vertical to horizontal ratio of 1:1) yielded a better history match for water production compared to the conventionally used value of 1:10. Water saturation maps were generated at the start and the end of production to highlight saturation distribution within the reservoirs. The maps revealed that in the lower porous part, the oil was fully depleted around the wells but remained trapped in the undrilled areas.

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Structural and petrophysical controls on the remaining fluid distribution in the reservoirs of Gharif Formation before abandonment

Cited by 2 publications

References 17 publications

Matching of Water Breakthrough in Low Resistivity Oil Reservoir Using Permeability Anisotropy

Matching of Water Breakthrough in Low Resistivity Oil Reservoir Using Permeability Anisotropy

Matching of Water Breakthroughs in a Low-Resistivity Oil Reservoir Using Permeability Anisotropy

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