水平井加重钻井液垂沉规律实验研究

EXPERIMENTAL RESEARCH ON THE VERTICAL SETTLING LAW OF WEIGHTING DRILLING FLUID IN HORIZONTAL WELLS

加重钻井液在倾斜井眼的特殊垂沉现象，将加剧水平井钻井过程中井眼净化的难度。通过自制垂沉实验仪器，研究加重钻井液中重晶石材料在常温常压下的静态垂沉现象、规律以及钻井液静切力对垂沉的影响。室内研究表明，加重钻井液在倾斜状态下的垂沉程度可以用倾角和钻井液流变性关系的函数来表示。垂沉是一种沉降不稳定现象，实质是钻井液体系处于短距离重力沉降环境和Ｂｏｙｃｏｔｔ效应下，其下部在单位时间内的颗粒沉积量及底层密度均比垂直状态时大，因而若提高钻井液体系的悬浮能力，即可防止加重钻井液出现垂沉。

The special vertical settling of weighting drilling fluid in inclined hole will increase the difficulty of hole purification during drilling of horizontal wells.The research of static vertical settling of 13ante in weighting drilling fluid at ordinary temperature and atmospheric pressure,and the influence of gel strength of drilling fluid on vertical settling shows that the degree of vertical settling of weighting drilling fluid in inclined hole can be expressed by the relation between dip and rheology of drilling fluid. The vertical settling is an unsteady phenomenon,it's caused when the drilling fluid at short-distance gravitational settling environment and under Boycott effect, the depositional volume of grain at the lower part of drilling fluid in unit time and the density in the bottom are higher than that in vertical 11de, so as to prevent the vertical settling of weighting drilling fluid, it's necessary to improve the suspension capability.