This paper outlines the successful integration of subsurface, water handling, well surveillance and production operations teams across the North Kuwait asset to significantly improve the operating procedure for waterflooding the Sabiriyah Mauddud field. This effort required a new way of managing this reservoir in NK: a multifaceted approach of balancing voidage with injection, conducting extensive surveillance/analysis within the reservoir to assess the efficacy of various courses of action and, most significantly, adjusting various teams' "key performance indicators" (KPIs) to align injection and production allowables with sound reservoir management principles.
An innovative, unified information management system was used to monitor voidage replacement ratio (VRR) to provide a basis for pattern balancing. Extensive surveillance operations provides the data necessary to monitor individual pattern balance, watercut performance, optimize areal sweep efficiency by adjusting injection and production allowables, assist in planning water shutoff operations, and design new completions.
Waterflooding the Cretaceous Mauddud reservoir is in an early stage of operations. Water injection commenced in 12 of 17 predrilled waterflood patterns in 2000. These wells were drilled on an inverted nine-spot pattern with spacing of 250 acres per well to quickly provide coverage over the major portion of the reservoir. Surveillance data indicates the reservoir is relatively well connected. Pattern VRR, pressures, and watercuts were somewhat out of balance prior to engaging in this effort. Now, individual waterflood pattern balance is significantly improved and the field-wide VRR is ~1.
Sound reservoir surveillance and waterflood management procedures implemented within a diverse group of teams that have performance goals aligned with "best practice" has resulted in effectively re-balancing this major waterflood. This effective integration of teams retains the flexibility to adjust for an ongoing development of this super giant field.
The Sabiriyah field was discovered in the 1950's with the drilling of the SA-001 well. Production commenced in 1958. Located in North Kuwait (Figure 1), Sabiriyah Field consists of several stacked pay intervals, trapped in a North-South elongated faulted anticline with approximately 500 ft. of present-day four-way closure (Figure 2). Present-day closure has been modified slightly by a recent structural tilt, which occurred after the trap was filled with oil. To date, the major oil pay intervals in the Sabiriyah field occur between 7,100–8,300 ft. drilling depth and include various high-productivity Burgan sandstones overlain by a more moderate-permeability shallow-water ramp-carbonate, the Mauddud. These reservoirs were normally- pressured at the time of discovery.