Completion Philosophy Rejuvenation to Maximize Well Potential in Challenging Sour HPHT North Kuwait Jurassic Gas Fields

Abstract

It always remains a big question, what is the best way to complete a well for maximum potential? Selecting proper well completion is critical to overcome reservoir challenges and ensure efficient stimulation treatments and well intervention specially in challenging deep highly deviated wells targeting complex high heterogenous HPHT conventional and unconventional tight carbonate gas reservoirs such as North Kuwait Jurassic gas fields (NK JGF). This paper will demonstrate the added value, experience, challenges and lessons learned of completion strategy rejuvenation and paradigm shift journey of NK JGF's wells completion till landing to a combination of three main completion schemes based on structured selection criteria. This is led by integrated team to enhance overall well production potential, overcome reservoir and intervention operations challenges, and early production delivery to achieve asset strategic production target. The Jurassic gas fields produces mainly from deep HPHT, conventional and unconventional tight carbonate reservoirs. The recovery from such complex heterogeneous reservoirs is extremely challenging if conventional development strategies are applied. Due to the high reservoir tightness, permeability contrast among different flow units and dual permeability effect (matrix and natural fractures), well productivity potential significantly depends on the effectiveness of subsequent stimulation treatments of such complex heterogeneous reservoir to improve well productivity and connect the natural fractures. Selecting proper well completion is critical to overcome such reservoir challenges and ensure efficient acid stimulation treatments of such complex formations that need convenient diversion mechanism during the stimulation to enhance the productivity of each individual reservoir layer and enable future flexibility of selective re-stimulation and reservoir management. Based on solid understanding and field experience, the NK JGF asset team has applied a step change in completion strategy from initial legacy 3.5" tubing and 5" cemented liner at early development phase, then 4.5" monobore cemented completion, to recently 4.5" openhole multistage completion until landing on combination of these three main completion schemes based on structured selection criteria considering integration of all subsurface domains and operation teams. Improving the completion efficiency is continuously helping to overcome the NK JGF's reservoirs complexity, improve the overall well potential and associated cost in addition to fast track well delivery to production to meet asset production target. Based on gained experience, an integrated protocol for well completion selection, staging design and installation procedures of multistage completion workflow has been built by the integrated multidisciplinary team to ensure standard process across fields which can be used for application in other fields. This paper describes the learnings of the Jurassic field from the completion and production perspective.