利用图版法预测欠平衡钻井井壁稳定性

Prediction Wellbore Stability in UBD by Using Collapse Circle Chart

与常规钻井液钻井相比,欠平衡钻井技术在提高机械钻速、保护油气层等方面有着无可比拟的优势;其中井壁稳定是欠平衡钻井过程中最为突出的问题。目前对于欠平衡钻井没有一套合理的井壁稳定分析方法,给现场钻井带来很多困难,需要进行欠平衡钻井井壁稳定性预测方法研究;通过建立坍塌周期图版来预测欠平衡钻井井壁稳定性。介绍了井壁坍塌过程动态计算模型研究、坍塌周期图版绘制、现场试验验证和现场应用。结果表明:国内外首次以坍塌周期图版的形式进行欠平衡钻井井壁稳定性动态预测,坍塌周期图版能够确定合理的钻井液密度,预测井壁坍塌的程度,为欠平衡钻井的设计和施工提供理论依据,是欠平衡钻井技术的配套技术,具有良好的推广应用前景。

Underbalaced drilling （UBD） technology has great advantage in enhancing ROP, protecting reservoir and so on compared to conventional drilling. The wellbore stability is the most important aspect in UBD. Nowadays, without the appropriate wellbore stability analytic approach of UBD and then bring great difficulties. So need to re- search the predictive approach of wellbore stability in UBD through developing the collapse circle chart. Borehole collapse process dynamics calculation model is introduced, how to develop the collapse circle chart of the wellbore, the field experimental verification and the field application. The experiment results demonstrate that the collapse circle chart of the wellbore can help to design the appropriate drilling fluid density, predict the degree of the well collapse, offer the theory reference for UBD design and operation. The wellbore collapse circle chart is the support technology of UBD, has bright filed application prospect.