高密高粘钻井液四相分离技术研究

Study On 4-phase Separation of Drilling Fluid with High Density and High Viscosity

对钻井过程中地面返回流体的四相分离进行了分析研究,重点是高压、超高压气层钻井和井控时,发生气侵的高密度、高粘度钻井液的分离系统研究。文中提出了几种典型的立式两级分离系统方案,第一级除去地面返回流体中的大宗气体、泡状液体和固体颗粒,第二级对弥散在混合液中的小起泡进行深度分离。由于钻井液随粘度的增大,越难发生气液分离,为除去该钻井液中极难分离的小气泡,提出了几种高效的离心式气液分离器设计方案。一些方案通过实验证明是合理、可行的,分离器实验模型的除气性能稳定、显著,从而为高压、超高压气层安全钻井及井控提供了保障。

4-Phase separation for drilling fluid recovered from ground during drilling process was studied, and the focuses were emphasized on the separation system of drilling fluid with high density and high viscosity that could cause gas cut at high-pressure, ultra high-pressure gas layer and well control. Several typical vertical two-stage separation systems were presented in this article. Their first stage was to remove the mass gas, bubble fluid and solid particles in the drilling fluid back from ground; the second stage was to deeply separate the small air bubbles dispersing in the mixed fluid. The viscosity increase of drilling fluid could cause more difficulties of gas-liquid separation. Several efficient design projects of centrifugal gas-liquid separator were put forward to remove the small air bubbles. Some projects were proved to be reasonable and feasible, the model separators were efficient to remove gas bubbles and could provide guarantee for safely drilling at high-pressure, ultra high-pressure gas layer and well control.