不同支撑剂组合对复杂裂缝支撑效果的影响

Support effect of different particle proppant combinations on complex fractures

致密储层进行滑溜水压裂时,常常采用不同支撑剂组合的注入方式来提高压开裂缝的充填效果,而目前关于复杂裂缝中支撑剂组合运移规律方面的研究较少。文中采用大型可视化复杂裂缝颗粒运移模拟装置(考虑壁面粗糙度和滤失的影响),研究了不同支撑剂组合在复杂裂缝中的运移规律及支撑效果,并提出了采用近井带砂堤角度和近井带未充填程度2个参数来评价支撑剂在近井带裂缝中的铺置情况。研究结果表明:先小后大组合的支撑剂对于复杂裂缝的支撑效果最好,小于40/70目的支撑剂在复杂裂缝中有较好的运移能力,而20/40目支撑剂主要依靠重力作用进入分支缝而形成斜坡状砂堤;先大后小组合的支撑剂既不利于近井裂缝支撑,也会影响后期小颗粒支撑剂在分支缝中的运移;混合组合支撑剂会形成分选,呈层叠状分布,从而限制小颗粒支撑剂的运移。

In the slickwater fracturing of tight reservoirs,combined proppant particle size injection is often used to improve the filling effect of fractures.At present,there are few studies on the transport mechanism of the different particle proppant combinations in complex fractures.In this paper,the migration of proppants in complex fractures with different combinations of proppants is compared and evaluated by a large visual complex fracture particle migration device considering fluid loss and roughness.Two parameters,near-well sand dune angle and near-well unfilled degree,are put forward to evaluate the laying of proppant in near-well fractures.The results show that the combination of first small particle and second large particle size has the best supporting effect on complex fractures.The proppant less than 40/70 mesh has better migration ability in complex fractures.The 20/40 mesh proppant mainly relies on gravity to enter the branch fracture to form a sloping sand dune.The combination of first large particle and second small particle will not achieve good support for near-well fractures,and also affect the migration of small size proppants in branch fractures in the later stage.The combination of mixed proppants will produce separation and form a cascading distribution,which limits the migration of small size proppants.