With the desired objective of increasing Oil production, the Operator initiated a high inclination well drilling campaign utilizing open hole completions with Inflow Control Device (ICD) screens in Burgan (sandstone) reservoirs. The approach dramatically reduces the effect of water and gas breakthrough, while optimizing production rates throughout the completion interval.
Challenges encountered while drilling these high inclination wells included increased non-productive time resulting from interbedded formations with varying formation pressures, wellbore instability in the reactive, stressed shale sections and hole cleaning challenges.
A non-aqueous reservoir drilling fluid (RDIF) system was customized with extensive laboratory testing to overcome the challenges and protect the reservoir from drilling fluid damage. The formation damage phenomena investigated included foreign particle invasion, formation clay swelling, chemical incompatibility, oil wetting of the reservoir rock, emulsion blocking and fluid invasion (water blocking).
Based on the reservoir rock morphology and the calculated pore throat size distribution, the bridging particles type, size distribution, and concentration to be selected to rapidly establish a tight thin filter cake and prevent the invasion of filtrate and fine drilled solids deep into the formation to minimize damage to reservoir and avoid getting differential stuck pipe incident.
Removal of skin damage resulting from external and internal filter cake deposition while drilling reservoir with invert emulsion fluid is vitally important to enhance production. The customized near-wellbore damage remediation system constructed around an in-situ acid precursor was designed to improve hydrocarbon recovery.
This paper also summarizes engineering best practices developed while drilling, tripping and performing PST to achieve the operators well objectives. The lessons learned during these applications were incorporated into future wells to standardize operating procedures and improve field performance.