地层模块尺度下的新型钻井液侵入物理模拟系统

A new physical simulation system of drilling mud invasion in formation module

在攻克大尺寸样品模块饱和加压、侵入室设计、钻井液侵入装置密封保压和钻井液侵入全过程动态监测等关键技术难题的基础上,设计并制造了地层模块尺度下的钻井液侵入多功能物理模拟系统,总结了钻井液侵入过程中砂岩地层模块的电阻率、压力和泥饼参数的变化规律。介绍了该系统的设计思路、组成和各部分的功能,实施了砂岩地层模块钻井液侵入实验,结果表明:盐水钻井液侵入过程中,地层模块径向电阻率向远离井筒方向依次开始减小;侵入初期泥饼逐渐形成,其厚度增加而孔隙度、渗透性降低,地层模块径向压力梯度迅速降低,侵入中后期泥饼性质、砂岩模块径向压力梯度趋于稳定。设计的系统仿真度高、利用率高、可操作性强,可用于揭示砂岩储集层钻井液侵入机理、分析钻井液侵入特征、完善测井响应钻井液侵入校正方法等。

After several key technologies, including the saturation and pressurization of large sample, design of invasion room, sealing and pressure maintaining of the apparatus, and dynamic monitoring of the entire invasion process were solved, a multifunctional physical simulation system of drilling mud invasion in formation module has been designed and built. By using the system, the variation patterns of formation module resistivity, pressure and mud cake parameter during the invasion are summarized. The design idea, components, and fimctions of each component of the system are introduced in this paper; and a drilling mud invasion experiment in the sandstone formation module was done. The experiment results show that the radial resistivity of formation module decreases in turn during brine drilling mud invasion; at the beginning of invasion, the mud cake is gradually formed with the increase of its thickness and the decrease of its porosity and permeability, and the radial pressure gradient of formation module decreases rapidly; in the middle and late periods of invasion, the mud cake properties and the radial pressure gradient of formation module become stable. The designed system, with high simulation degree, high utilization ratio and good maneuverability, can be used to reveal the invasion mechanism of drilling mud in sandstone reservoirs, analyze invasion characteristics, and improve invasion correction method for logging response and other researches.