Measuring Procedures Of Stress Sensitivity For CBM Formation

Test method for the previous research workers should use the research field of stress sensitivity on CBM formation has many defects,CBM formation and at home and abroad there is no recognized stress sensitivity evaluation method,this paper summarizes the CBM reservoir stress sensitivity test method of indoor research difficulties through research,try to influence the coal rock samples scale,water saturation and gas saturation stress sensitivity degree as a breakthrough in the conventional oil and gas reservoir evaluation method based on the developed test sample of coal or rock in different scale,water saturation,gas saturation and the influence of the 3 factors under the stress sensitivity experiments with test sample scale,water saturation and gas saturation,the coal rock stress sensitivity measurement results are also different.Among them,along with the coal sample size increases,the stress sensitivity is weak,and when the sample size reaches 50 mm in diameter,75 mm in length,the scale effect disappeared;along with the coal water saturation increases,the stress sensitivity is intensified,the confining pressure from 2.5MPa to 9.0MPa,0% of the average water saturation permeability decreased by 84.8%,100% of the average water saturation the permeability decreased by 96.1%;and with the coal containing gas saturation increases,the stress sensitivity also showed increasing trend,confining pressure from 2.5MPa to 11 MPa,the gas saturation of 0% average permeability decreased 88.9%,gas saturation 100% penetration rate fell by an average of 95.6%.The results show that the test sample size,water saturation and gas saturation are the 3 main factors affecting the stress sensitivity evaluation of coal and rock.The size of the test sample is closer to the actual characterization of formation permeability,gas and water under the condition of more realistic simulation of coal reservoir gas reservoir environment,and thus eventually forming a suitable for the improvement of CBM reservoir stress sensitivity test method.