The Longest Super Slim 3-7/8in High Angle Slant Profile Drilled Successfully into the Least Stress Direction – Kuwait Case Study

Abstract The objective is to drill a long super slim 3-7/8in high angle 76º inclination profile to maximize the primary reservoir exposure cutting through a depleted zones in a harsh drilling condition and pressure regimes into the least stress direction. The actual drilled profile was checked first from surface down to the last 5.0in liner shoe depth at 18,044’ MD to measure the wellbore tortuosity and predict the cased hole friction factor the buckling areas to assure an optimal weight on bit delivery expected while drilling. A full analysis for the open hole was taken using a nearby wells with similar inclination shorter intervals and were able to derive the expected friction factor to model the right Bottom hole assembly (BHA) with iterations to enhance the capability of drilling a long interval without sacrificing the well stability or directional control to overcome the drilling challenges. The section length was planned to drill 950ft though the reservoir and so, BHA was designed to have a mud motor to control the directional profile and overcome the high downhole torque expected +/- 6,000 ft-lbs and the sinusoidal buckling was 7k lbs WOB. The bit selection played an important rule to choose the right PDC bit with the optimum cutter's distribution and rake angle for more aggressive cutting efficiency to drill with the minimum WOB applied. The reservoir pore pressure and fracture gradient were also derived from the nearby wells to decide keeping optimized mud weight and Rheology for high permeable depleted limestone zones while drilling in azimuth 117º near to the least stress direction in the field. All the drilling and subsurface challenges were sorted and analyzed with an engineered solutions techniques to overcome and deliver the well to the planned TD at 19,000ft MD with total section length of 956ft meanwhile, keeping an optimized drilling parameters and mud rheology to drill the maximum reservoir exposure in a super slim high angle 76º trajectory. This paper provides an overview regarding the preparations on how to drill a high angle well profile in a super slim 3-7/8in hole size and how to overcome the challenges in terms of the buckling limit and the narrow channel of a mud weight range using a solution engineering solution technique and how the execution was taken to fulfill the subsurface reservoir requirements. First time in Kuwait for assigned direction company to drill a long 3-7/8in super slim deep well. Differential sticking hazards were addressed by geomechanical modeling for the depleted reservoir to decide the mud weight window for optimum hole cleaning, Stabilizing the underbalanced formations and controlling the ECD following the best practice for hole cleaning in addition to the usage of the mud motor to overcome the low buckling limit and develop a direction control on the well profile.