Unreliable determination of in situ stress orientation by borehole breakouts in fractured tight reservoirs: A case study of the upper Eocene Hetaoyuan Formation in the Anpeng field, Nanxiang Basin, China

Unreliable determination of in situ stress orientation by cross multipole array acoustic logging in fractured shale reservoirs

“…Hence, the long axes of borehole breakouts are generally oriented perpendicular to the S Hmax direction. 5,6,47 DIFs occur when the stress concentrated around the borehole exceeds the tensile strength of the wellbore wall. 48 Hence, DIFs develop parallel to the S Hmax direction.…”

“…5 Hydraulic fracturing is often adopted for deep in situ stress measurements in tight reservoirs, shales, and coal seams. 5,6 The basic principle of the anelastic strain recovery (ASR) method for measuring stress is that the rock has a viscoelastic property, that is, elasticity and viscosity exist at the same time. 49,50 The experiment was completed in the ASR in situ stress measurement laboratory of the Chinese Academy of Geological Sciences.…”

“…Careful screening and diagnosis are needed in studies of the direction of in situ stress. [1][2][3][4][5][6] After nearly a century of development, a variety of comprehensive methods can be used to determine the stress state in reservoirs. [7][8][9][10] Stress evaluation has become an indispensable basic method for reservoir engineering [4][5][6] ; oil, gas, and coal exploration 8,[11][12][13][14][15] ; and oil and gas engineering design, drilling, and completion.…”

“…[1][2][3][4][5][6] After nearly a century of development, a variety of comprehensive methods can be used to determine the stress state in reservoirs. [7][8][9][10] Stress evaluation has become an indispensable basic method for reservoir engineering [4][5][6] ; oil, gas, and coal exploration 8,[11][12][13][14][15] ; and oil and gas engineering design, drilling, and completion. [16][17][18][19] Stress evaluation also has important applications in the development of well pattern deployment, 4,6,20 prediction of reservoir fractures, [21][22][23][24] wellbore stability, 4,19,25 hydraulic fracturing, [26][27][28][29] and sand control in oil and water wells.…”

“…Rock complexity makes it impossible to accurately determine the value and direction of in situ stress; thus, we must address large variations and uncertainties in stress measurement results. Careful screening and diagnosis are needed in studies of the direction of in situ stress 1–6 . After nearly a century of development, a variety of comprehensive methods can be used to determine the stress state in reservoirs 7–10 .…”