页岩气藏水平井多级压裂裂缝扩展模型研究

Propagation model of multi-stage hydraulic fracturing for horizontal wells on shale gas reservoirs

"水平井+多级压裂"技术是目前页岩气藏开发的一项核心技术,并已取得商业化成功.该技术的应用有效改变了压裂的作用区域,但对于裂缝分支的起裂和扩展程度认识的不清,导致水力压裂设计较为粗糙.本文应用最小作用量原理,使裂缝系统的流体压力能、流体动能、弹性能、岩石表面能和摩擦损失热能构成的拉格朗日函数满足哈密顿积分条件,建立了预测最大储层改造体积(Stimulated Reservoir Volume,SRV)时裂缝虚拟个数和虚拟长度模型,其中裂缝虚拟个数可以用来描述裂缝的复杂性.对裂缝虚拟个数和裂缝生长率模型单因素分析结果表明,杨氏模量、范宁摩擦系数等对裂缝虚拟个数的影响显著,裂缝净压力、范宁摩擦系数对裂缝生长率的影响显著.威远-长宁页岩的现场研究实例表明,W1井的裂缝虚拟个数比N1井强,W1井的储层体积改造程度比N1井好,且W1井的裂缝复杂程度更好,而裂缝虚拟个数概念能够反映压裂裂缝的实际复杂性.这为完井工程师提供了理论指导,以提高页岩气储层井压裂改造设计和分析准确性.

Multi-stage Moreover,hydraulic fracturing of horizontal wells is a key technique used for exploiting shale gas has reservoirs changed at present.fracturing hydraulic it has become a commercially the successful knowledge technique.about The application of this technique the the the area effectively.Due to lack The of the the initiation and extension of fracture branches,fracturing design is rough.application and of the minimum action principle makes the Lagrangian function satisfy the Hamiltonian elastic integral condition,surface the and the Lagrangian frictional function loss is composed of the fluid pressure and energy,fluid kinetic energy,fracture energy,rock energy describe of energy.The virtual The number virtual length the models of are and established,the which rate can complexity show of fractures.single and factor analysis on virtual number have model growth on model fracures that net the Young’s modulus Fenning Fanning’s friction coefficient a significant effect the number of fractures,The and the pressure and friction coefficient have a significant effect on the growth well rate of fractures.than field well,study and in Weiyuan-Changning reservoir block show is that the than virtual that number N1 of and fractures the in W1 is higher well that of N1 the volume can of W1 well actual better of well,complexity of W1 is better.The virtual number of fractures design reflect the complexity,shale which provides theoretical guidance for completion engineers to improve the and analysis accuracy of gas reservoir fracturing.