车66区块钻井过程井底压力波动及渗流规律

摘要

Drilling operations in the Che-66 Block are susceptible to blocking, formation collapsing, lost circulation, blowout and other complexities. Based on fluid dynamics in annulus and with consideration to formation permeability features, magnitudes of swabbing pressure and surge pressure produced during tripping and drilling operations were analyzed, together with effects of drilling fluid viscosities, densities, well depths and ROPs. In accordance with linear seepage theory, models for unidirectional fluid spherical centripetal flow and plane radial flow were deployed to determine seepage patterns and lost circulation of drilling fluids during penetration of reservoir formations under negative pressure. Research results show that higher bottom-hole differential pressure and formation permeability may lead to higher speed in seepage of formation fluids and higher volume of drilling fluids lost. The conclusions highlighted fluctuation in bottom-hole pressure during drilling, together with seepage pattern and relevant influencing factors. The research results can provide necessary foundation for optimization of borehole structural design.%针对车66区块钻井过程中易出现的阻塞、地层垮塌、井漏甚至井喷等问题，基于环空流体力学并结合地层渗透性特征，分析了在起、下钻及钻井过程中产生的抽汲压力和激动压力的大小，以及钻井液黏度、密度，井深和钻井速率对其影响的规律；依据线性渗流定律，单向流体球面向心流和平面径向流模型研究了井底负压差下进入、钻过储层的渗流规律变化及正压差条件下钻井液漏失情况，得出井底压差越大、地层渗透率越高，地层流体渗流速度越高，钻井液漏失量越大。该分析结果揭示了钻井过程中井底压力波动和井下渗流规律及其相关影响因素，为井身结构设计优化提供了必要依据。