水力压裂加砂施工曲线形态剖析

Curve Shape Analysis of Sand Hydraulic Fracturing Operation

压裂是油气井增产的一项重要技术措施。依据200多口井压裂资料,分析了其“加砂”工序中泵压、排量、混砂比曲线随时间的变化形态,归纳出“加砂”曲线的5种类型:下降型、下降稳定型、波动型、上升型、稳定型。研究认为下降或下降稳定型曲线形态主要是因被压开地层裂缝缝高的增加;波动型曲线形态主要受地层物性严重非均质性影响;上升型曲线形态是受地层渗透性差、层薄影响,造成缝高延伸受阻,水平延伸缓慢或是携砂液在地层缝内严重堵塞,产生砂卡,泵压突然上升;稳定型曲线形态可能是地层滤失量的增加,使施工泵压长时间维持常量。现场施工可根据加砂曲线形态,合理调整“加砂”施工参数,保证油井施工顺利进行。

F racturing operation is an important measure of stim-ulation.Based on fracturi ng data from over200wells,vari-ations of curve shapes of pump pressure,di scharge capacity and sand-fluid ratio with time are analyzed and5curve types are summarized including decline type,stabilized de-cline type,wave type,asc ending type and stabilized type.Curve shapes of decline type and stabilized dec line type are the results of enlargement of fracture height;that of wave type is controlled by heterogeneity of physical proper-ty;that of ascending type is influenced by the low perme-ability and small layer thickness;and that of sta bilized type is possibly caused by increasing of filtration loss.Parame-ters o f sand fracturing operation can be adjusted according to the curve shapes to ens ure smooth operation.