| Shaly loose sandstone is defined as the unconsolidated sandstone with the clay contant between 15-50%,its permeability is low,but the shaly loose sandstone reservoir would be one of the next target reservoirs,and hydraulic fracture is an important way of developing low permeability reservoir,so understand the fracture geometry of hydraulic fracture in shaly loose sandstone reservoir would play an essential role in exerting the use of fracturing during production process.Through the study of composition characteristics and menchanical characteristics of shaly loose sandstone,three types of crack propagation and its composite fracturing mode are preliminary analyzed.Due to the rich data of the formation,the X-1 layer of X field in Wenchang is selected as the experimental simulation object.The correlative parameters of shaly loose sandstone are determined,the emulational core making method of shaly loose sandstone is established,and the simulated core formula is optimized.Based on the sample simulated method of shaly loose sandstone,adjust the formula of sample for fracturing appropriately,made the sample for fracturing of shaly loose sandstone which meets the needs of experiments.The true triaxial hydraulic fracturing experiment is carried out under different simulated ground stresses with three kinds of fracturing fluids and the experiments results are described in macroscopic view.On the basis of dissection or CT scans of sample for fracturing,the fracture geometry of shaly loose sandstone is microscopic analyzed,especially the affect of fracturing fluid type,stress difference and clay content to fracture geometry respectively.Combing macro and micro analysis,shaly loose sandstone fracturing fracture geometry could be divided into four kinds: the linear broken single wing straight seam,the herringbone broken wings straight seam,the striated wings variational seam and asymmetric multi-fracture system with multi-morphological fracture zone. |
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