地层压力预测技术在准噶尔盆地钻井中的应用

准噶尔盆地东部地区存在多套不同的压力层系，给钻井工程带来了很多困难。地层压力的准确计算对于合理、经济地选用钻井液性能，防止井喷、井漏、井塌等复杂钻井情况的发生具有重要意义。为此，分析了准噶尔盆地东部地区异常压力成因机理，认为水热增压、烃类生成和黏土矿物转化不是该地区异常压力主要成因，欠压实作用才是造成该地区异常压力的主要机理。以现场测井资料和实际施工数据为基础，应用测井资料解释方法对该地区的A1井等6口井进行了地层压力预测。结果表明：奇古组以下地层存在异常高压，钻井时应提高钻井液密度来实现平衡钻井；地层压力预测值与实测值相对误差最高为4.3%，预测精度高，达到了指导现场安全钻井和井控的目的。

Application of formation pressure prediction technology to drilling in Junggar Basin

Multiple pressure systems of formations existing at eastern Junggar Basin bring challenges to drilling engineering. It is known that exact calculation of formation pressure is significant not only for the proper and cost effective selection of drilling fluid properties, but for the prevention of drilling problems like blowouts, lost circulations and well caving. We analyzed the mechanism of abnormal formation pressure development at the eastern Junggar Basin and recognized that the main reason for the abnormal pressure in this area was not the water being heated, hydrocarbons generation and clay minerals being converted, but the under compaction effects. Based on the logging and drilling data collected at the field of this area, prediction of formation pressure was made through the interpretation of the logging data for 6 wells, including the well A1. The results show that for the abnormally high pressure below the Qigu Formation, the drilling fluid density should be increased to achieve balanced pressure drilling; the highest relative error is 4.31% between the predicted and the actual formation pressure values, reflecting high prediction accuracy, so this technology of formation pressure prediction can be the guidance for safe drilling and well control.