致密储层水平井体积压裂段间距优化方法

目前致密储层的主要开发方式为水平井+体积压裂改造,但对于天然裂缝不发育的储层,通常难以形成复杂的裂缝网络系统,不能够达到预期的改造目标。针对这种情况,在研究压裂过程中诱导应力场变化的基础上,建立了诱导应力和原地应力相叠加的数学模型,结合缝间应力干扰分析结果,形成了体积压裂段间距优化方法。研究结果表明,利用水力裂缝之间的应力干扰中和原始地应力有利于形成复杂裂缝,并且在同样的原始地应力条件下,随着裂缝高度和裂缝内净压力的增加,形成复杂缝网的段间距会增加。现场实例计算验证了通过应力干扰确定水平井压裂段间距优化方法的可行性,该优化方法对致密储层水平井分段体积压裂设计有一定的借鉴意义。

Method of optimizing the spacing between volumetric fracturing stages in horizontal wells in tight reservoir

At present, the main development method for tight reservoirs is horizontal well with volumetric fracturing. But for reservoirs lack of natural fractures, it is usually difficult to form complex fracture network system, and the desired stimulation objectives can not be achieved. To solve this problem, based on the research of the induced stress field variation during fracturing, a mathematic model was built by the superposition of the induced stresses and in situ stresses. And the method of optimizing the spacing between volumetric fracturing stages was created based on analysis of the inter-fracture stress interference. The research results show that complex fractures can be created by neutralizing the original geostress by the inter-fracture stress interference. In addition, under the same original geostress conditions, with the increase of fracture height and net pressure inside the fractures, the interval space which creates complex fracture network also increases. Field practical calculations verified the feasibility of the optimization method for fracturing stage spacing in horizontal wells, which is of some reference significance to the design of staged volumetric fracturing in horizontal wells in tight reservoirs.