页岩气藏压裂支撑剂沉降及运移规律实验研究

Study on proppant settlement and transport rule in shale gas fracturing

页岩气资源储量巨大,但由于页岩渗透率低,往往需要压裂才能有效开采。滑溜水压裂有利于形成复杂的裂缝网络,是中外页岩储层压裂改造首选的压裂液体系。由于滑溜水粘度低,携砂能力差,增加了滑溜水压裂的风险。中国在该领域的研究尚处于起步阶段,尤其对滑溜水携砂支撑剂沉降及运移规律的研究更少,同时缺乏必要的实验手段。为此,设计了裂缝模拟装置,通过实验模拟了施工排量、缝宽、支撑剂粒径、压裂液粘度和砂比等参数对裂缝内支撑剂沉降和运移规律的影响,获得不同参数下支撑剂的沉降速度和水平运移速度,分析了各因素的影响规律,并求解了各因素对支撑剂沉降速度和水平运移速度的修正系数。结果表明,随着缝内流速和压裂液粘度的增大,支撑剂沉降速度减小,水平运移速度增大;随着支撑剂粒径与缝宽比值和砂比的增大,支撑剂沉降速度和水平运移速度均减小。

Huge reserves of shale gas reservoir,is usually of no natural capacity,is often needed to be fractured in order to produce effectively.The slick-water which has low viscosity and proppant carrying capacity is used in shale gas reservoir fracturing.Nowadays,most of the studies about the settlement and transport rule of proppant are theoretical,and the field application always relies on the former experience or software simulation with only few experimental studies.The experimental method is implemented through the fracture physical model to study the impact of the pumping rate,the fracture width,the proppant types and the sand concentration on the proppant settling velocity and horizontal displacement velocity.The correction coefficient of various parameters on the settling and transport velocity is obtained through experiments.Theoretical models of proppant settlement and transport rule in shale gas reservoir fracture are established.It is of instructive significance to the shale gas fracturing design and construction.