Optimal Design of Casing Programs for Ultra-Deep Wellsin the Shunbei Oil and Gas Field

As exploration & development of the Shunbei Oil and Gas Field continues to deepen, the original casing program shows the problems such as high drilling risk and low efficiency, and it is necessary to optimize the casing program. With this in mind, we utilizled the logging data of drilled wells, to calculate the pore pressure, fracture pressure, and collapsing pressure of formation with Drillworks software, and the calculation results were corrected by combining with the drilling data of drilled wells and rock mechanics test results. Hence, it was possible to obtain the formation three-pressure profile of Shunbei Oil and Gas Field, and further define the necessary sealing points for geological engineering according to the profile. Based on the necessary sealing points, by comprehensively considering the drilling technical level and drilling/completion requirements, 5 types of casing program were designed. By predicting the drilling periods and drilling costs of those 5 types of casing program, and comparing the advantages and disadvantages, a four-spud unconventional casing program was selected properly. After this casing program was used in the Shunbei Oil and Gas Field, the ROP was increased by 30%–40%, the drilling period was shortened by 33–45 d, and all the wells reached the target layers smoothly. It indicated that the optimized casing program in Shunbei Oil and Gas Field improved drilling efficiency and reduced drilling risks.