The Mechanics Of Multi-branch Fractures Formation With Hydraulic Fracturing

Hydraulic fracturing is an important measure for low permeability reservoirs to increase production.The part of geological conditions of the reservoir is complex. After conventional fracturing still unable to increase production. Reservoir stimulation effect is poor. Therefore, carry out the new hydraulic fracturing technology measures research. It has a positive meaning to improve the production and promote the development of hydraulic fracturing method.In this paper, for the problems Hailaer Oilfield low permeability reservoirs in conventional hydraulic fracturing process conversion effect is not obvious, proposed under conditions that "fiber + particle" temporary blocking, Multi-branch fractures hydraulic fracturing process measures. Paper through experimental methods evaluated the temporary blocking effect of "fiber + particle" temporary blocking agent. Theoretically researched the initiation mechanism of the initial cracks and branch fractures. And conducted multi-branch fractures hydraulic fracturing temporary blocking physical model experimental research. And compared theoretical conclusions with the field test results.Paper based on "fiber + particle" temporary blocking mechanism, carried out "fiber + particle" temporary blocking agent laboratory evaluation experiment. Researched effect of particle and fiber concentration on the temporary blocking effect., the degradation of fiber in temporary blocking agent. Adopt the methods that combining theoretical and experimental researching on the multi-branch fracture formation mechanism. According to fracture mechanics and elasticity theory, considering artificial fracture induced stress field. Established a near-wellbore zone more branch joints initiation fracture mechanical model. Analyzed factors affecting of the multi-branch wellbore fracture initiation fractures. Based on fracture mechanics analying fracture tip stress field of Temporary blocking point.,according to compound stress theory established multi-branch joints in-fractures turning initiation fracture model. According to this model, get on multi-branch fracture fracturing field examples calculation. Verified multi-branch fracture fracturing feasibility. According to the results to analyzed factors affecting of the multi-branch joints Initiation fracture. Consistent with the conclusions of the theoretical model established.The last, as the example B14 wells, applied multi-branch near-wellbore fracture initiation fracture mechanical model calculated branch joints initiation pressure is 31.9MPa, real initiation pressure of 33 MPa, error is 7.4%; calculate crack initiation angle is 42.4 °, the real value of 41.8 °, error is 1.4%. An example S13 wells, Calculate in-fractures several more branches, three turns fracture fracturing real initiation pressure and calculated error is smaller, error range from 1.1% to 6.1%, the same trend. Field test ensure that the authenticity and practicality of the mechanical model.Paper presents the application temporary blocking means forming a multi-branch fracture hydraulic fracturing technology, and through theoretical calculation model describes a multi-branch sew crack law, the results of the paper can guide the multi-branch fracture hydraulic fracturing design and site construction.