The Characteristics Of Present-day In-situ Stress In Gas Shales Of The Key Area In The Northern Guizhou

In this paper,the characteristics of present-day in-situ stress in gas shales of the key area in the northern Guizhou are studied by the methods of hydraulic fracturing,anelastic strain recovery,log interpretation and numerical simulation.Analyzing the measured data or logging interpretation data of ST1,TX1,FC1,AY1 well.The results indicate that the?_H value is 5.60MPa~60.98MPa,the?_h value is 5.05MPa~51.87MPa,the?_v value is 3.30MPa~66.06MPa.The measured in-situ stress value has a linear growth relationship with depth.When the depth is less than 1300.00m,the vertical stress is not maximum principal stress and the stress state is?_H>?_h>?_v,?_H>?_v>?_h.When the depth is more than 1300.00m,the vertical stress becomes maximum principal stress and the stress state is?_v>?_H>?_h.In the study area,the orientation interval of the maximum horizontal principal stress is N25°W~N90°W,and more concentrated between N50°W~N75°W.Therefore,the dominant orientation of the maximum horizontal principal stress is NWW.The diversity coefficient of horizontal stress is close to 0.27 in the two depth position in the shale reservoir of Niutitang formation.The diversity coefficient range is 0.127~0.168 in three depth position in the shale reservoir of Niutitang formation.The diversity coefficient range is 0.148~0.180 in the shale reservoir of Longmaxi formation.The preliminary analysis of shale reservoirs in Niutitang formation in FC1 well and Longmaxi formation in AY1 well are better fracturing,and TX1 well is relatively poor.The stress value,orientation and horizontal stress diversity coefficient obtained by stress field numerical simulation are basically close to the measured and explained results.