Implementing Pattern Waterflood in a Complex Carbonate Reservoir, North Kuwait

Commercial production from Raudhatain Mauddud carbonate reservoir in North Kuwait started in late 1957. The production was maintained at low rates until 1998 when it was decided to initiate waterflood for enhancing oil rate and reserves. Field-scale pattern waterflood began in November 2000 after successful waterflood pilot test carried out in 1998.

In order to reduce technical and economic risks arising from uncertainties associated with reservoir development the entire Mauddud Waterflood Development Project was divided in two phases- Sea Water Injection Phase1 (SWIPh1) and Sea Water Injection Phase2 (SWIPh2). SWIPh1 is fully operational and involves initial development of central portion of the reservoir using six inverted 9-spot patterns where rock and fluid quality is good. Successful water injection in these patterns not only allowed reservoir pressure to build quickly reflecting good areal and vertical connectivity it has also led to a three-fold increase in daily oil rate. Time-lapse PLTs in injectors and producers have proved of immense help in identifying high permeability zones causing early injection water breakthrough. Consequent remedial operations have resulted in much improved pattern performance. Frequent measurement of static pressure in producers has helped maintain reservoir pressure above bubble point and periodic PGOR tests to balance injection and production in individual patterns.

Over the last couple of years development activities have gradually shifted to the peripheral or SWIPh2 area where wells are being pre-drilled to acquire new data ahead of commissioning of SWIPh2 facilities. Reservoir rock and fluid quality in this area are relatively inferior and therefore well injectivity and productivity are expected to be low.

Drilling in SWIPh2 area and ongoing extensive surveillance program particularly the RFTs and MDT/RCI sampling have helped improve understanding of the reservoir significantly. It is possible using these modern tools to better characterize individual layers of this complex reservoir. All this complemented with PVT analysis of the bottom hole samples from individual layers has resulted in a huge value addition to the full field simulation study that is underway to determine the most cost-effective future reservoir development option.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California