Experimental Study On Closure Pressure And Pressure-sensibility Of Fractured Shale Reservoir

Fractured shale gas reservoirs is an unconventional gas reservoir, many countrieshave found the industrial value of shale fractured reservoir.U.S. shale gas resources hasreached14.2×10¹²¹9.8×10¹²m³.Shale gas resources in china is very rich, estimate resourc-e volume of23.5×10¹²¹00×10¹²m³, and its exploration potential is huge. Shale gas exp-loration and development will become a new growth point for china’s future natural g-as energy, we must have a deep understanding of the characteristics of the fractured s-hale reservoir to guide such reasonable and cost effective gas reservoir development.Mudstone in the oil and gas is stored in the cracks. When the cracks fluid recovery, theoriginal balance to stressconditions change,cracks deformation lead to closure under stress,so that theformation permeability decreased production of oil and gas wellscan rapidly decline. Fractured shale closure one reason is that the plastic in Rock Mechanics-elastic s-train characteristics, the relation ship between stress and mudstone degree of crack closure, imposed fractured mudstone known as the stress sensitivity of mudstone. In thi-s study, through theoretical studies were analyzed for themudstone degree of crack closur-e and its impact on oil and gas exploration; In this study, through theoretical studies wereanalyzed for themudstone degree of crack closure and its impact on oil and gas exploration;While mudstone sandstone stress sensitivity to contrast and mudstone, in-depth to reveal th-e principles and mechanisms of thestress sensitivity of different types of rock. Asked thecha-racterization parameters of the mudstone fracture closurepressure, and quantify the closed le-vel; Theoretical and experimental analysis, the following conclusions:（1）changes in t-he external stress increases the fractured shaleporosity magnitude of the changes;（2）the pe-rmeability of thefractured shale with external pressure and internal pressureincrease was no-nlinear relationship.The external pressuresensitive index of the sensitivity index is much l-arger than theinternal pressure. Either external pressure or internal pressure,the sensitive index emerged as the loading process is greaterthan the uninstall process, the sensitive index;（3）sandstonestress sensitivity is greater than the sensitivity of the mudstonestress;（4）penetrat-ion as a characterization of mudstone theparameters of the degree of crack closure in the la-boratoryconfining pressure permeability curve to determine the critical pressure point of t-he crack closure; the latter were to change theflow pressure and confining pressure, mudst-one fracture closurepressure under different types of pressure change;（5）sandstoneclosurepressure greater than the mudstone fracture closurepressure;（6）mudstone crack closure press- ure of the external stress is greater than the closure pressure of internal stress.In this stud-y, to determine fractured mudstone reservoirdevelopment methods, work systems and the e-xploitation rate tomaintain proper formation energy, thereby protecting the reservoircapacit-y, improve the ultimate recovery of some significance.