Engineered Fluid Design Helps Drilling the Longest Horizontal Section in Record Time – A Case Study from Turkey

Abstract

Drilling extended lateral sections to maximize reservoir exposure is key to optimizing field production and data recovery. However, it presents peculiar challenges not limited to hole-cleaning, wellbore stability, narrow drilling windows, and excessive torque and drag. Thus, customizing the fluid system to drill lateral sections requires information to understand the formation characteristics, including geomechanical data to determine the correct mud weight window, a precise selection of optimal fluid rheological properties, good inhibition, and lubricity, which are of foremost importance for extended-reach drilling (ERD) wells. The reservoir section of the well presented in this paper was previously drilled unsuccessfully twice, as the targeted zone was not reached. During the drilling phase, a large amount of non-productive time (NPT) was observed due to stuck pipe incidents, hole collapse, and then, hole cleaning issues were encountered while drilling. Another critical concern is the narrow mud weight window range, which causes the formation to break when Equivalent Circulating Density (ECD) increases beyond the pore pressure or fracture pressure of the formation. A new generation of High-Performance Non-Aqueous Based Mud (HPNBM) was engineered to drill these types of complicated, long horizontal intervals matching the drilling performance required to drill such sections and deliver a perfect gauge hole. This HPNBM provides high shear-thinning properties, an excellent low-end rheological profile, and rapid-set/easy break gels. This paper presents a successful well delivery of drilling the longest horizontal section in the country within a record amount of time. The previous attempts were carefully studied to identify the challenges associated during drilling and considered while designing this HPNBM. The high-performance non-aqueous based mud system proposed with stress caging technique was successful, economic, and drilled successfully with zero non-productive time (NPT) related to drilling fluids. Engineering software was utilized as hole cleaning is critical for drilling the horizontal sections to reach the targeted depth and run casing to the bottom. This paper presents the longest horizontal section (4,200 ft) to be drilled to the targeted depth as planned in Turkey. A comprehensive analysis that includes the planning phase, application, techniques, and performance of the mud system will be presented.