东海油气田深部泥页岩特性及钻井液技术研究

针对东海油气田从玉泉组到平湖组钻井过程经常出现剥落掉块导致蹩钻、蹩扭矩、起下钻遇阻等问题，开展了东海油气田泥页岩特性及钻井液技术研究，研究中采用了X射线衍射、理化性能测试、扫描电镜以及高压压汞分析了东海地区泥页岩井壁失稳的机理，提出了纳微米微孔封堵和活度平衡的钻井液技术对策，获得了一套适合于东海油气田深层泥页岩井壁稳定的海上反渗透型钻井液技术并开展了室内评价和现场应用，应用井与邻井相比，12(1/4)"井段划眼时间从137.75 h减少到39.50 h，循环时间从56.75 h减少到35.75 h，单井划眼和循环时间节约近5 d。

A Study on the Characteristics of Deeply Buried Mud Shale and Drilling Fluid Techniques in Oil and Gas Fields of East China Sea

In view of the frequent occurrence of problems such as bit-bouncing, torque distortion, and tripping resistance caused by peeling and chipping during drilling operations across the Yuquan and Pinghu formations of the oil and gas fields of the East China Sea, the present study investigates the characteristics of mud shale and drilling fluid techniques in the oil and gas fields of the East China Sea. X-ray diffraction, physical and chemical property tests, scanning electron microscopy, and high-pressure mercury injection were adopted to analyze the mechanisms of borehole destabilization in the mud shales of the East China Sea area. Based on these analyses, nano/micro pore sealing and balanced activity drilling fluid techniques were proposed to resolve the aforementioned issues. On this basis, a set of offshore reverse-osmosis-based drilling fluid techniques suitable for stabilizing deep mud shale borehole walls in oil and gas fields were developed for the East China Sea. Laboratory evaluations and field applications of these techniques were performed, and it was observed that compared with a neighboring well, the reaming time of the experimental well of size 12(1/4)" decreased from 137.75 h to 39.50 h and the circulation time decreased from 56.75 h to 35.75 h, resulting in time savings of close to 5 d for reaming and circulation for a single well.