Identifying Subsurface Characteristic or Attributes that enabled Produced Water Disposal and Increasing Production in a Mature Field Sabriyah North Kuwait: A case study

Abstract

Abstract Mature fields generally require water injection to either provide pressure support to sustain oil production and or arrest decline. The injected water produced along with oil as fluid requires separation for reinjection or disposal. Surface disposal requirements often creates increased environmental scrutiny and regulatory compliance obligations may pose significant operational and cost challenges that can limit efficiency and profitability. A cost and operationally efficient approach must include subsurface disposal. This project discusses an approach to identifying subsurface characteristic or attribute that allows for a cost effective approach to produced water disposal and enhancing oil production by 1-3% within a mature field. Identifying existing closed wells and formations with high capacity to handle the water disposal has a vital role in the overall field development by allowing currently closed highly water cut wells put back on production. Initial step was to nominate potential non-reservoir formation, if any, that is suitable for produced water disposal. Several closed wells penetrating these formations provide cost effectiveness without having to trigger new Capital expenditure. Detailed geological, seismic and cement bond evaluation of existing closed wells helped to narrow down and identify candidates for disposal opportunities. An Early Cretaceous (Aptian) Shuaiba formation with thickness ranging in 150-450ft across Sabriyah field selected as suitable. The formation, though non-hydrocarbon bearing in study area, is a highly dolomitized limestone with characteristic packestone and grainstone facies. The carbonate sedimentology highly fractured cavernous porosity with history of causing drilling operations challenges includes excessive losses, bad cement bonds among others. Suitable zones within candidate wells identified and perforated for Injectivity testing. A combination of high precision temperature and noise logs along with injection logging tools used to evaluate and establish Injectivity within the Shuaiba formation. Preliminary results confirmed that Shuaiba formation is a good candidate disposal formation that can handle surplus water production. Initial estimates indicated disposal intake capacity of up to 14400 bwpd at 1200-psi wellhead pressure. Disposal has continued for over twelve months within the pilot well and several more wells identified for repeat performance. The first successful operation to support produced water disposal within the Shuaiba formation in Sabriyah Field North Kuwait. Subsurface injection and disposal in matured Sabriyah field has contributed to overall water cycle handling and management strategy. Asset owner are now able to sustain and enhance production by putting back more closed or high water cut wells back on production with potential to increase total field production by up to 10% without incurring significant operating or capital expenditure.