疏松砂岩水平井分段压裂分层开采一体化工艺研究

Study on the Integrated Technology of Segmented Fracturing and Stratified Mining of Unconsolidated Sandstone Horizontal Wells

针对疏松砂岩具有高孔、高渗、且强度低、塑性强的特点,裂缝起裂与延伸机理较为复杂,储层非均质性强,裸眼水平井全井段单次压裂起裂位置具有不可控性。压裂充填是为了提高疏松砂岩储层产能,增强低渗层导流能力,解除近井地带污染,实现防砂、增产、调剖和控水等多重目的的有效技术手段。通过对水平井全井段单次压裂和多段压裂的产能模拟对比分析,结果表明,疏松砂岩裸眼水平井分段压裂是可行的、必要的。研制了一套适用于疏松砂岩地质的裸眼水平井分段压裂、分层开采一体化工艺管柱。该工艺管柱通过裸眼封隔器对长水平段进行封隔,每层段设置有双层复合筛管、充填滑套、生产滑套和循环滑套,其中双层筛管基管不打孔。一趟管柱下入即可实现裸眼水平井分段压裂充填防砂作业,且留井管柱保留有分层开采手段,无需后期单独下入分采管柱即可选择性隔离含水、含气储层。该工艺管柱可为海上疏松砂岩储层的高效开采、防砂控水提供新的思路和方向。

Frac-packing is an effective technical means to improve the productivity of unconsolidated sandstone reservoirs,to enhance the conductivity of low permeability layer,to relieve the contamination near the well,and to achieve sand control,yield increase,profile control and water control.Unconsolidated sandstone has the characteristics of high porosity and high permeability,low strength and strong plasticity,complicated fracture initiation and extension mechanism,strong reservoir heterogeneity,and uncontrollable fracture initiation position in the whole well section of open-hole horizontal wells.The results show that it is feasible and necessary to stage fracturing of open-hole horizontal wells in loose sandstone through the comparative analysis of productivity simulation of single fracturing and multi-stage fracturing.A set of integrated technologies of stage fracturing and stratified mining for open-hole horizontal wells in loose sandstone geology is developed.In this process,the long horizontal section is sealed by an open hole packer,and each section is equipped with double-layer composite screen,filling sleeve,production sleeve and circulation sleeve,in which the double-layer screen base pipe is not drilled.The sand control operation of open hole horizontal wells can be realized by stage fracturing and filling in a single run,and the stratified mining means are retained in the remaining well string,and the water-bearing and gas-bearing reservoirs can be selectively isolated without the need to separately run the separate production string in the later stage.This process can provide a new idea and direction for high-efficiency recovery and sand and water control of offshore unconsolidated sandstone reservoir.