Study On Influencing Factors Of New Fractures In Refracturing Of Horizontal Wells

The horizontal well refracturing technology has become an important means for the development of low permeability reservoirs and the tapping potential of the old wells.The physical processes and mechanisms of the initiation and extension of the new fractures during the refracturing of the horizontal wells are not yet clear.The control conditions and influencing factors of the new fractures which produce various morphological characteristics at the time of fracturing are of great significance both for the study of the refracturing mechanism and for the field production.In this paper,the rock mechanics parameters of the well are obtained by the rock mechanics parameter test,and the rock brittleness along the horizontal wellbore is evaluated,and a rock fragility suitable for hydraulic fracturing is proposed based on the rock fracture energy evaluation method.Then,the in-situ stress field near the horizontal well is obtained by the best square approximation of the finite element model by the acoustic emission test of the core.Based on the obtained rock mechanics parameters,the in-situ stress field and the production data of the well pattern injection,the dynamic stress field near the horizontal well is collected.Finally,the new fracture morphology such as the extension direction,the complexity of the cracks and the communication with the adjacent cracks are analyzed in the way of the new fracture at different initiation positions by means of the indoor hydraulic fracturing physical simulation test.The influencing factors such as rock mechanics,geo-stress distribution,pump speed,the old fracture spacing and wellbore orientation were studied.Finally,it is concluded that the influence of horizontal stress difference and the old fracture spacing is obtained,and the influence of pump speed and wellbore orientation is small.