Successful Exploitation of Non-Traditional Clastic Siderite Reservoir Through Integration of High Performance Drilling, Geomechanics and High Definition Reservoir Mapping Technology

Abstract

Almost all worldwide oilfields which have been producing for a long time have reached brown level of maturity. Given the foreseeable increase in global oil demand and consumption in the near future, operators need to be innovative in finding new resources and developing plans to meet the production demand. Oilfield service companies have parallely kept the pace by continuously improving their technologies and evolving their product offering to support activities from exploration to production phases. Sabriyah Lower Burgan reservoir in North Kuwait has been producing for a long time after its discovery. Since oil production is mostly from massive and coal sand members for long time, exploitation of new reservoir is needed to sustain the field productivity. The non-traditional siderite layer (SID3) had been identified by Kuwait Oil Company (KOC) as a potential source of incremental oil production. The reservoir has a lower productivity index and cannot flow significantly in vertical wells. SID3 has a relatively thin layer (5-20 ft TVD) with high lateral variations and presence of regional coal, making it highly challenging for drilling operations. There were many cases of wellbore instability while drilling wells in Lower Burgan in the past. Geological uncertainty generated by pinch out sand bodies in the reservoir section, led to scratching unstable shales and coal layers prone to collapse, thus resulting in stuck pipe events due to hole pack-off. Large volume and size of cavings, restricted circulation, high over pull, tight spots while tripping, and severe time-dependent wellbore instability due to shale sloughing contributed to the event and resulted in costly sidetracks. The geomechanics study is a key technology in the oilfield industry to prevent wellbore instability, via optimization of well trajectory and proper mud weight selection. Application of the study outputs helps minimize drilling risk, diminish non-productive time and ensure well completion within the expected deadline. Horizontal well design is deemed as the most effective way to exploit the SID3 layer, and the application of High Definition Distance-To-Boundary (DTB HD) technology can help the operator mitigate geological uncertainties, maximize reservoir contact and hence boost production rate. Integration of proactive Distance-To-Boundary technology, geomechanics study and meticulous pre-drill preparation have led to the successful completion of several horizontal wells in the SID3 layer. As a result, the operator gained a significant increase in oil production compared to the vertical wells. The well production also benefited from advanced completions technology with inflow control devices, handling other production related matters like presence of shale/silty layers for optimum hydrocarbon recovery. This proves that high-end technologies, coupled with multi discipline domain expertise and high-performance teamwork, is key to sustain the industry's ability to respond to the increase in global energy demand.