Regional Temperature Gradient: A Key To Tilted OOWC

Stenger, Bruno

doi:10.2118/53197-ms

Cited by 13 publications

(5 citation statements)

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“…However, the large west-to-east tilt in Central Haradh is more difficult to explain by the same calculations, as the depth to the equilibrium surface in the aquifer would be much greater. The shallow OOWC noted on Central Haradh's west flank is localized and appears to be a physical singularity (Stenger, 1999). Fresh, recent aquifer waters have been sampled in this area and temperature variations seem to correlate with production-related pressure variations.…”

Section: Discussionmentioning

confidence: 90%

“…Finally, conclusions on the origin of the tilted OOWC will be submitted together with a brief review of implications for the on-going development of the southernmost area of Ghawar. As indicated by Aramco (1959) and discussed by Stenger (1999) and Stenger et al (2001), the tilted OOWC in Ghawar does not lend itself to a straightforward classification. According to Wender et al (1998), the growth history of the Ghawar structure consisted of the following four main phases: Hercynian Orogeny (Carboniferous); Zagros rifting (Early Triassic); Early Alpine Orogeny (Late Cretaceous); and Late Alpine Orogeny (Tertiary).…”

Section: Introductionmentioning

confidence: 94%

“…Given the variable oil and water densities as measured in Ghawar, these surfaces are tilted. Stenger (1999) suggested the following:…”

Section: Fluid Properties and Static Equilibriummentioning

confidence: 99%

“…It is possible to calculate the equilibrium of the oil and water columns across the structure based on the above assumptions (Stenger, 1999). At the northern end of Ghawar (salinity 225,000 ppm TDS), the OOWC is 6,650 ft deep, whereas the calculated OOWC (from an average salinity of 65,000 ppm TDS) is 6,368 ft at the southern end of the Haradh sector.…”

Section: Fluid Properties and Static Equilibriummentioning

confidence: 99%

“…The apparent paradox was explained by variable salinity at the regional scale. To the best of our knowledge, this concept had not been applied to tilted OOWC prior to the work of Stenger (1999).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Tilted original oil/water contact in the Arab-D reservoir, Ghawar field, Saudi Arabia

Stenger¹,

Pham²,

Al-Afaleg³

et al. 2003

GeoArabia

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A review of the electrical logs, fluid properties, and production history of 195 flank wells drilled in the Arab-D carbonate reservoir of the Ghawar field, Saudi Arabia, showed that the original oil/water contact was regionally tilted. The contact was about 200 ft higher in the southern Haradh sector than in the northern Shedgum and ‘Ain Dar sectors. In Haradh, the fluid contact was also locally tilted down from west to east by as much as 800 ft. In the reservoir, the oil and aquifer densities changed from lighter oil and denser water in the north to lighter water and denser oil in the south. Decreasing methane content caused the increase in oil density and a reduction in the water density was the result of a salinity decrease. The evolution of fluid densities was closely correlated to a decreasing regional-scale geothermal gradient, probably indicating that temperature controlled the distribution of fluid densities. Simple analytical calculations showed that the magnitude of the observed tilt of the original oil/water contact from north to south might be explained by changes in fluid densities. On the western flank of central Haradh, the Arab-D reservoir water was anomalously young and fresh and this created a large salinity gradient between the western and eastern aquifer legs. This anomaly was explained by pressure-dependent vertical leakage along the Wadi Sahba structural trough between the Arab-D reservoir and the shallower Biyadh aquifer. Consequently, the integrity of the Hith Formation seal above the Arab-D reservoir might be locally compromised under particular conditions. A full-field reservoir simulation model, specific geological features, and examples from the technical literature supported a static interpretation of the tilted original oil/water contact in the Arab-D reservoir of Ghawar through the combined effects of changes in oil and water densities.

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Section: Discussionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 94%

“…Given the variable oil and water densities as measured in Ghawar, these surfaces are tilted. Stenger (1999) suggested the following:…”

Section: Fluid Properties and Static Equilibriummentioning

confidence: 99%

Section: Fluid Properties and Static Equilibriummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%