Experimental Research Of Fracturing Fracture Extension Law On The Gucheng Coal Rock

CBM is a clean energy gas with coal associated,and with methane as main component occurrence in coal seam,about 90% of them are adsorption on coal matrix pore fracture surface,10% free between pore fissure.Coalbed methane resources in China is about 36.8 trillion cubic meters,the third largest in the world,and natural gas reserves.As a new important unconventional gas,CBM is taken more and more seriously.However,Methane development effect in qinshui basin coalbed is not ideal,the fracturing effect is not obvious.So they need deep research in coal and rock rupture mechanics,adaptability of fracturing construction process parameters and the joint network development controlling factors.This paper takes CBM hydraulic fracturing reconstruction project in Gucheng block of qinshui basin as the background,on the basis of block based information collection,the research of coal and rock structure and mechanical properties test,and based on the analysis of coal and rock structure,three axis hydraulic fracturing physical simulation experiments,researched the mechanical characteristics of coalbed methane reservoir in Gucheng blocks and the original ground stress analysis.Then,through fracturing tests of coal and rock samples,to describe the coal and rock fracture after fracturing,analysis the fracture patterns of coal and rock fracturing.Experiments show that the coal rock with natural fracture and cleat development,directly affect the direction of hydraulic fracturing cracks crack and fracture morphology,and much less stress effects on the fracturing cracks.The porosity is communicated in the process of perforating,perforation stress field changed and Fracture preferred natural cleat direction of surface crack,and communicate with each other;In-situ stress effects on the fracturing fracture significantly difference between the coal rock and the conventional reservoir,the effect is more complicated,the model constructed according to the conventional reservoir of in-situ stress effect cannot be adapted to the coal reservoir.In the end,on the basis of experimental analysis,combined with field engineering,provides the theory basis for hydraulic fracturing operation parameters optimization for Gucheng block.