Equation of State Characterization of a Deepwater Gas Condensate Field with Complex Geochemistry

Abstract

An 8-component Equation of State 3D model coupled to Petroleum Experts’ GAP has been applied to characterize Deepwatergas field rich gas condensate reservoirs to capture compositional grading and phase behavior effects in the reservoir and production facilities. The Deepwatergas field consists of North and South reservoirs separated by a graben. The North reservoir contains a near-critical gas condensate (CGR of ~ 200 stb/MMscf) with evidence of compositional grading and a speculative oilrim while the South reservoir contains lean condensate (CGR ~ 60 stb/MMscf) with heavy oil and a tar mat at the base of the reservoir. Deepwatergas gas wells (one each in North Reservoir and South Reservoir) are tied back through a 26mile flowline to the host, hence understanding the hydraulics of the subsea flow system was also an important part of the performance evaluation, and key to future performance prediction and re-development decisions. The results from the study helped explain the producing CGR in the North reservoir, which remained constant below field dew point, and also provided an assessment of gas compression requirements over the producing life of the field.