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

Abstract

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 parameters during the invasion are summarized. The design idea, components, and functions 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. Key words: drilling mud invasion, physical simulation, formation module, mud cake parameters