提高超深裂缝性储层改造体积技术研究及应用

Application and improvement of ultra-deep fractured reservoir stimulated volume technology

超深储层天然裂缝对改造井产量影响大,但其发育形态复杂,动用天然裂缝提高改造体积,对改造技术要求高。结合储层天然裂缝发育特征,基于单弱面理论及摩尔应力圆强度准则分析,证明改造水力裂缝影响范围内的天然裂缝开启是动态变化的过程,提高人工裂缝缝内净压力有利于提高开启天然裂缝的比例。在超高闭合应力作用下,剪切滑移天然裂缝、酸液未处理或酸液处理的张性激活天然裂缝,可作为油气流动通道,流体通过能力有限。获得高强度支撑的张性开启天然裂缝具有较高导流能力,可与人工裂缝共同构成油气渗流主通道,是构成储层内部高效缝网的主框架、提高裂缝储层改造体积的关键。通过论证改造过程提高井底净压力对张性开启天然裂缝的作用,研究酸压及加砂复合改造技术、缝内暂堵措施、加重压裂技术及小粒径与组合粒径支撑剂相结合的技术措施,综合形成提高裂缝性储层有效改造体积技术,取得较好应用效果。研究对超深高应力裂缝性储层提高有效改造体积具有借鉴意义。

Natural fractures in ultra-deep reservoirs have great impact on the production of the fractured wells,but their developmental patterns are complex,and the use of natural fractures to improve the stimulated volume requires high stimulation techniques.Combined with the natural fracture development characteristics of the reservoir,based on the single weak plane theory and Moore's stress circle strength criterion analysis,it is confirmed that the natural fracture opening within the influence of the hydraulic fracture is a dynamic process,and increasing the net pressure within the hydraulic fracture is conducive to increasing the proportion of natural fractures.The shear-slip natural fractures,acid-untreated or acid-treated tensile-activated natural fractures under ultra-high closure stress can be used as oil and gas flow channels with limited fluid passage capacity.Tensile-opened natural fractures that obtain high-strength support have high flow-conducting capacity and can constitute the main oil and gas seepage channel together with hydraulic fractures,which is the main framework constituting the efficient fracture network and the key to improve the stimulation volume of the fractured reservoir.By demonstrating the role of improving the net pressure at the bottom of the well in the stimulation process to open the natural fracture by tension,the compound stimulation technology of acid-fracturing and sand-adding,temporary plugging measures within fractures,augmented fracturing technology,and technical measures combining multi-size particle proppants are studied to form a comprehensive technology to improve the effective stimulation volume of fractured reservoirs and achieve better in-situ application results.This study can be used for improving the effective stimulation volume of ultra-deep and high-stress fractured reservoirs.