煤层气水平井充气欠平衡钻井注气工艺研究　　

Study on gas injection technique of aerated underbalanced drilling for CBM Horizontal Wells

龚才喜 梁海波 古冉

GONG Caixi LIANG Haibo GU Ran

中国石化华北油田分公司工程处，河北任丘　062552 西南石油大学，四川成都　610500

Engineering Technology Department of PetroChina Huabei Oilfield Company, Renqiu 062552, China Southwest Petroleum University, Chengdu 610500, China

充气欠平衡钻井是目前煤层气钻井中最常用的技术手段，如何在控制注气压力，注气量以及排量等参数的情况下，使得钻进时既能满足携岩要求，又能有效地控制井底压力是一个难题。应用FLUENT软件，通过对不同的注气压力、注气量以及排量条件下的计算模拟，得出U型井直井造穴处的压降规律，并基于此，优选确定出一套合理的工艺参数，确保在充气欠平衡钻井过程中，既能形成期望流型、满足携岩要求，又能有效控制井底压力。文中通过一口井的实钻数据建立了分析模型，并进行了计算模拟，最终优化出注气压力、注气量和泵排量等参数，总结出其变化规律。该研究成果对保障钻井作业安全及优化钻井作业有一定的借鉴作用。

Nowadays, aerated underbalanced drilling becomes one of the most commonly used techniques in coalbed methane drilling. It is difficult to satisfy the rock cuttings portability requirement and control the stability of bottom hole pressure, while controlling the gas injection pressure, rate, and volume. The pressure drop performance is obtained at the corresponding cave through numerical simulation by FLUENT software under different gas injection pressure, rate and volume. So a reasonable set of technical parameters are selected, which can guarantee the expected flow type to fulfill the rock portability requirements, and stabilize the bottom hole pressure during aerated underbalanced drilling. An analyzing model is built up through the real-time parameters from one well, and the gas injection pressure, rate and volume are optimized, following with the parameter varying rules. The results have some guidance to ensure drilling safety and optimize drilling operations.