井下压力温度测试技术在徐深5井的应用

针对深层欠平衡钻井存储式随钻井下压力温度测试工具和配套软件存在的问题，进行了改进与完善，解决了井下仪器的振动问题，延长了钻井过程中的有效工作时间，改进后的工具在徐深5井进行了应用，该井是大庆油田深层加快勘探的一口重要的欠平衡预探井。通过应用，实测出该井第三次开钻井段钻井过程中不同情况下的井底压力、温度。利用关井求压时的井底压力变化能够准确地计算出地层压力、井底负压值的大小，对比设计井底压力值，为科学指导下步钻井，精确控制井底负压值提供依据。利用井底压力的实测值与理论值之间的误差分析表明，由于岩屑的影响造成井底压力增加，导致井下出现过平衡，影响欠平衡钻井的效果。同时，还介绍了实测井底压力温度数据在环空岩屑携带的情况、实际钻头压降大小和井下流体温度变化等方面的应用。

DOWHOLE PRESSURE AND TEMPERATURE MEASUREMENT TECHNOLOGY USED IN WELL XUSHEN-5

According to the problems related with downhole pressure and temperature recording tools and softwares in deep UBD wells, improvements have been made, to mitigate the vibration of the downhole tools and to elongate their working life. The improved tools have been field tested on Well Xushen-5, an important preliminary prospecting UBD well of Daqing Oilfield meant to quicken the deep exploration activity. During the test, the downhole temperatures and pressures under different well conditions in the third-spud section were actually measured and recorded. After combining with the downhole pressure variations during the well shut-in, the formation pressure and underbalance value at the well bottom were accurately calculated. And by comparing with the designed hole bottom pressure, experiences were obtained to provide scientific guidance on precise control of underbalance pressure downhole in future drilling. The analysis of the actual measured pressure and the theoretic pressure of the tested well indicated the drill cuttings had caused the increase in downhole pressure, resulting in an overbalance condition which prevented the desired advantageous outcome of UBD. Application of recorded downhole pressure and temperature data in analysis of upward return of drilling cuttings in the annulus, the actual pressure drop on bit, and the change of downhole fluid temperature, etc. are further discussed in this paper.