Research On Fracturing Technology Of Horizontal Wells With Deep Shale Gas

Sichuan basin is rich in shale gas resources,and only longmaxi formation and qiongzhusi formation have natural gas resources exceeding 39 × 1012m3 in two sets of Marine shale reservoirs,among which shale gas resources in the deep(3,500m deep)account for more than 85%.China has formulated relevant development plans,but at present,deep shale gas development technology has not made a breakthrough,which is mainly reflected in the existing shallow shale gas staged fracturing tools,plug pump delivery and perforation combined process,and the low adaptability of fracturing technology to deep shale reservoirs.Under high temperature and pressure conditions,the packer performance of the segmented tool decreased,and the drilling and grinding capacity of the coiled tubing bridge plug was limited after fracturing.During the bridge plug pumping,because of the long trajectory of the well,higher pump displacement is required to provide greater pumping thrust to overcome the friction of the cable in the wellbore,and the cable weakness has a certain pulling force,thus increasing the risk of the bridge plug pump release.After the implementation of existing shallow shale gas fracturing technology in deep shale gas Wells,the fracture complexity and reservoir reconstruction volume(SRV)are low,and the productivity of gas Wells after fracturing is not high.In view of the above problems,it is of great significance to carry out the research on deep shale gas completion and fracturing technology to solve the practical problems in the field and realize the effective development of deep shale gas resources.Based on the investigation of the fracturing tools for horizontal Wells at home and abroad,and combined with the characteristics of deep shale gas development,the evaluation and optimization of deep shale gas fracturing tools were carried out.Based on the problem of bridge plug pumping in deep shale gas Wells,a cable with an outer diameter of 9mm was developed to improve the tension between the cable body and the weakness,and a fine calculation model of pumping displacement was established to realize fine optimization of pumping displacement.Based on the comprehensive calculation model of induced stress for fracture propagation in hydraulic fracturing,the methods to improve the complexity of fracture were put forward,such as shortening the length of subsection to increase induced stress interference between fractures,increasing the net pressure in fracture by whole-process pumping of low-viscosity slip water with high displacement,and temporarily blocking steering technology.Proppant diverting capacity calculation model is established,using the measurement data of indoor experiments verify the model accuracy,rely on the model was carried out by proppant number of layers,embedded,crushing effect on fracture diverting capacity,put forward by adding proppant shop buy layer,improve the proppant added amount to ensure that support high fracture diverting capacity of technological process.The research results have been successfully applied in the field.The results show that the dissolvable plug segmented fracturing tool can meet the needs of field operation.After fracturing,there is no need to drill and mill the coiled tubing plug,which reduces the test cycle by more than 5d.The optimized cable and pumping process was 13.9%more efficient than that before optimization.After the implementation of deep shale gas fracturing technology in Wells Zi2 and H2,the test production is respectively 45 X 104m3/d and 22 X 104m3/d,realizing the effective utilization of deep shale gas resources.