提高砂岩储层人工裂缝复杂度的压裂技术及其应用

Study and Application on Improving Hydraulic Fracture Complexity in Sandstone Reservoir

提高裂缝复杂度是提高储层改造体积的重要组成部分。为明确砂岩储层复杂裂缝形成的控制因素及实现方法,在物理模拟实验结果的基础上,建立了天然裂缝储层形成复杂裂缝的数学模型,采用数值模拟方法研究了应力场,提出并试验了多种施工工艺。研究结果显示砂岩储层形成复杂裂缝的必要条件包括改变应力场、发育天然裂缝或提高缝内净压力。其中天然裂缝是砂岩储层能否形成复杂裂缝最重要的因素,储层最大最小主应力差越大,天然裂缝与人工裂缝夹角越大,形成复杂裂缝所需缝内压力越大;多缝应力干扰可有效改变应力场。现场监测及压后分析证实试验井形成了复杂裂缝。该技术为低渗尤其是致密砂岩油气藏的经济开发提供了有效手段。

Improving the fracture complexity is one of the most important parts to improve the stimulated reservoir volume.To understand when and how the complex fracture form in sandstone reservoir,a model is established to describe the natural fractured reservoir,the stress filed is analyzed by means of numerical simulation method and several treatment technical are brought forward based on the physical simulation experiment results.The analysis show that natural fractures,stress field inverting and elevating fracture pressure are the necessary condition to form complex fracture,and natural fractures are the most important ones.The bigger the principal stress bias and the orientation between hydraulic fracture and natural fracture are,the higher the fracture pressure is needed.Two and two more factures spread simultaneously could invert the stress field near the fracture.The monitoring and analysis show that the experimental wells form complex fractures by applying the technique.Therefore,the fracturing makes these oilfields with low permeability especially the tight sandstone oilfields be developed economically.