顺北油气田超深井井身结构优化设计

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

  • 摘要: 随着顺北油气田勘探开发的不断深入,原有井身结构开始显现出钻井风险大、效率低等问题,亟需优化井身结构。为此,利用已钻井的测井资料,利用Drillworks 软件计算了地层的孔隙压力、破裂压力和坍塌压力,并结合已钻井的钻井资料和岩石力学试验结果对计算结果进行修正,得到了顺北油气田地层的三压力剖面,根据地层三压力剖面确定了地质工程必封点。根据地质工程必封点,综合考虑钻井技术水平和钻井完井要求,设计了5种井身结构,通过预测5种井身结构的钻井周期、钻井成本,对比优缺点,选用了四开非常规井身结构。顺北油气田超深井采用四开非常规井身结构后,机械钻速提高30%~40%,钻井周期缩短33~45 d,均顺利钻至目的层。这表明,顺北油气田采用优化后的井身结构,提高了钻井效率,降低了钻井风险。

     

    Abstract: 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.

     

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