广谱“油膜”暂堵钻井液体系研究

Study on system of broad-spectrum oil-film temporary plugging drilling fluid

在钻井过程中,为达到保护油层的目的,通常根据油层的平均孔喉半径,在上部钻井液中加入合适粒径的暂堵剂,再配合胶体填充粒子将其改造为对油层具有保护作用的钻井液。但在实际井中,油层孔喉半径分布范围较宽,导致经改造后的钻井液仅对某井段具有较好的屏蔽暂堵效果,而对另外的井段则不能起到较好的保护油层作用。针对油层非均质性强、孔径分布范围较大、油层孔径难以准确预知等特点,根据室内岩样污染评价结果,提出了采用广谱“油膜”暂堵剂GPJ的暂堵技术。室内评价和现场应用表明,该钻井液体系不仅实现了对油层的广谱暂堵,而且保护油层效果更佳,可获得更大的日产油量。

To achieve the objective of protecting reservoir during drilling, the common means is to add proper graded temporary plugging materials, coupled with colloid filling particles in upper drilling fluid based on the average radius of pore throat in reservoir, which converts upper drilling fluid to reservoir protection fluid. However, in practice due to wide distribution of radius of pore throat, the converted fluids exert good shielding temporary plugging effects only at certain intervals, and can not exert function of protecting reservoir. Aimed at the reservoir of severe heterogeneity, wide pore radius distribution and unpredictability of pore radius, the method of using GPJ broad-spectrum temporary plugging agent for temporary plugging purpose was put forward based on the lab pollution evaluation results of core samples. The lab evaluation and field tests show that the drilling fluid system not only has broad-spectrum temporary plugging effect, but also bears the function of reservoir protection, thus increasing daily oil production greatly.