An Integrated Surface, Wellbore, and Reservoir Gas Management Approach for the Mature Mauddud Reservoir in Bahrain Field

Abstract

Bahrain oil field being the first oil discovery in the gulf region in 1932 is now in a mature stage of development. Crestal gas injection in the Mauddud reservoir has continued to be the strongest drive mechanism since 1938. Over the last five years, gas injection and fluid production rates have grown three folds with expanded drilling, workovers, and high volume lift activities however there are significant opportunities to increase oil production and optimize gas injection. Since 2009, a growing number of wells in Mauddud including newly drilled wells were being shut-in due to high gas to oil ratio (GOR) within the limited surface handling capacity. 30% of active producers accounting for 25% of oil production were shut-in by year 2014. Proper evaluation of this opportunity followed by the field implementation has helped to significantly improve the oil production rate, reserves base, and understanding of the Mauddud reservoir fluid dynamics. To manage the voidage replacement ratio (VRR) associated with the rapid increase in oil producers, gas injection in the Mauddud reservoir has grown from 180 mmscfd to 500 mmscfd between years 2009-2015. A phased optimization program has been implemented to identify the conformance issues, impact of faults, and for optimization of surveillance systems in order to maximize the oil recovery. The VRR optimization program has also shown opportunities to preserve the source gas from Khuff reservoir which is a valuable resource for the Kingdom of Bahrain’s future. This paper will describe the integration of gas shut-off workovers, selective gas compression, and VRR optimization as excellent gas management tools for maximizing recovery potential in the Mauddud reservoir.

Nationwide Subsidence in Bahrain Island: Drivers and Implications for Relative Sea-Level Rise

“…Bugti, et al [51] suggest that fault traps could also occur in the Awali field. For instance, numerous faults occur in the Wasia group formations, which contain the Mauddud reservoir, i.e., the largest oil reservoir of the Awali field [52]. The Awali field comprises sixteen oil and six gas reservoirs of fluids varying from tarry oil in the Aruma zone to dry gas in the Khuff zone [46].…”

“…To model this residual deformation (i.e., the sum of the deformations) over the Awali field, one would need to take into consideration the (i) volume of crude oil extracted in each reservoir and change (decrease) in the reservoir pressure [85], (ii) dynamics (decrease) of poroelastic parameters and compressibility of the rocks [85], (iii) weight of the overlying rocks [85], (iv) tectonic (anticlinal uplift) [85], (v) volume of gas or water injected to maintain the pressure and large gas cap to increase the oil production [52], but also (vi) pore pressure change of the aquifers, (vii) variation of the hydraulic head [86], (viii) volume of water encroaching.…”