Planning and Well Design for Kuwait Oil Company’s first North Kuwait Jurassic Horizontal Well - Case History

Abstract

Recent drilling activities in the State of Kuwait have focused on the search for high quality oil from the Jurassic formations. The wells drilled to these prospects are very challenging because of HPHT conditions, presence of high levels H 2 S and CO 2 , and narrow pore/fracture pressure windows.The targeted Jurassic formations are the Najmah-Sargelu and Middle Marrat, which are located below the Gotnia salt/anhydrite. These reservoirs consist of layered shales and limestones, which can be highly fractured. One of the main challenges in the effective development of these reservoirs is the ability of the wells to access a permeable interconnected vertical fracture network. Horizontal well profiles increase the probability of crossing multiple fractures or fracture swams, resulting in high productivity and reserve recovery per well.A 'Conceptual Project' was set up with the objective to design the first horizontal well to be drilled through the Najmah reservoir, in the North Kuwait fields. The challenges included; the establishment of an optimum well trajectory, drilling through the mobile salt section of the Gotnia at well inclinations above 60º, planning a pilot hole in the reservoir section to facilitate positioning of the lateral, identifying suitable water base mud system to improve image log quality, planning a high DLS openhole sidetrack just below 10 3/4" casing shoe and introducing a casing string (just above lateral) to address borehole stability concerns.To address these challenges a team based approach was established between operator and contractors, to develop the well design, detailed engineering and operational procedures. This paper will describe the methodology adopted during this well design process and the technical challenges faced and overcome.