In-situ stresses, abnormal pore pressures and their impacts on the Triassic Xujiahe reservoirs in tectonically active western Sichuan basin

Zhang, Jincai; Zheng, Hao; Wang, Guoli; Liu, Zhongqun; Qi, Yuanchang; Huang, Zhiwen; Fan, Xiaomeng

doi:10.1016/j.marpetgeo.2020.104708

Cited by 23 publications

(10 citation statements)

References 19 publications

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“…A case study is examined to illustrate this method. The studied field is a gas reservoir located in the Sichuan basin [39]. Wellbore breakouts and drilling-induced tensile fractures occurred simultaneously in certain depths in some boreholes, and Figure 8 In order to estimate horizontal stresses, a stress polygon needs firstly to be plotted.…”

Section: Maximum Horizontal Stress Estimation Frommentioning

confidence: 99%

In Situ Stress Prediction in Subsurface Rocks: An Overview and a New Method

Zhang

Yin

Zhang³

2021

Geofluids

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Methods for determining in situ stresses are reviewed, and a new approach is proposed for a better prediction of the in situ stresses. For theoretically calculating horizontal stresses, horizontal strains are needed; however, these strains are very difficult to be obtained. Alternative methods are presented in this paper to allow an easier way for determining horizontal stresses. The uniaxial strain method is oversimplified for the minimum horizontal stress determination; however, it is the lower bound minimum horizontal stress. Based on this concept, a modified stress polygon method is proposed to obtain the minimum and maximum horizontal stresses. This new stress polygon is easier to implement and is more accurate to determine in situ stresses by narrowing the area of the conventional stress polygon when drilling-induced tensile fracture and wellbore breakout data are available. Using the generalized Hooke’s law and coupling pore pressure and in situ stresses, a new method for estimating the maximum horizontal stress is proposed. Combined it to the stress polygon method, a reliable in situ stress estimation can be obtained. The field measurement method, such as minifrac test, is also analyzed in different stress regimes to determine horizontal stress magnitudes and calibrate the proposed theoretical method. The proposed workflow combined theoretical methods to field measurements provides an integrated approach for horizontal stress estimation.

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Section: Maximum Horizontal Stress Estimation Frommentioning

confidence: 99%

In Situ Stress Prediction in Subsurface Rocks: An Overview and a New Method

Zhang

Yin

Zhang³

2021

Geofluids

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“…According to the obtained publications in the petroleum geology field, the terrains of these coalbearing basins are generally flat with almost no faults or folds growing within them. However, there are tectonic fractures that are distinguished from the diagenetic and natural fractures widely distributed within these coal-bearing basins, and this phenomenon is more remarkable near the orogen-basin transition zone [15][16][17][18][19][20][21]. The formation of tectonic fractures has been associated with convergence actions close to or even far away from strike-slip faults and transpressional structures [18,22].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Compression and Torsion Fracture within 3D Printed Cementation-Weak and Porosity-High Sandstones

et al. 2023

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Cretaceous sandstones have weak cementation and high porosity while exhibit a high apparent brittleness. Compression and torsion (C-T) fractures are widely distributed in Cretaceous sandstones due to asymmetric tectonic convergence action. However, studies on C-T fracture formation and the mechanisms causing variability in Cretaceous sandstones containing no oil or gas are rare due to the challenges in sampling intact sandstone cores, despite their significance to mine shaft sinking. Therefore, this study used binder jetting-based 3D printing to prepare artificial Cretaceous sandstone and developed a real-time X-ray computed tomography- (CT-) aided torsion shear apparatus to test them. The test results showed that the 3D printed (3DP) sandstone had characteristic indexes that approached and even exceeded the lower limits of Cretaceous sandstone cores, thereby accurately representing the unavailable cores. Furthermore, the 3DP sandstones had anisotropic properties comparable to the sandstone cores. Under C-T action, the 3DP sandstone exhibited a pronounced strain gradient of 2.0 %/mm perpendicular to fracture inclination. The inclination angles of fractures formed under C-T action tended to increase as the cell pressure increased, and that approached the orientation angles of maximal principal stress. The maximal and minimal principal stresses exerted inclination-slip and width-stretching effects, respectively, on C-T fractures. But the effect of inclination-slip on the C-T fractures was stronger than that of width-stretching. This insight into C-T fracture formation will guide future studies on the fracture evolution and its disaster-dominating mechanisms arisen from disturbances by shaft sinking.

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“…1,2 However, it is usually difficult to fracture the reservoir with large in situ stress and strength, which requires fracturing pumps to provide higher operating pressure. 3 Sometimes, the fracturing equipment is limited by its power or pressure bearing capacity so that it fails to meet the demand. As a result, the fracturing operation cannot be carried out normally.…”

Section: Introductionmentioning

confidence: 99%

“…Hydraulic fracturing, as an effective stimulation measure, plays an irreplaceable role in the development and utilization of unconventional oil and gas resources 1,2 . However, it is usually difficult to fracture the reservoir with large in situ stress and strength, which requires fracturing pumps to provide higher operating pressure 3 . Sometimes, the fracturing equipment is limited by its power or pressure bearing capacity so that it fails to meet the demand.…”

Section: Introductionmentioning

confidence: 99%

Pulse injection simulation based on the coupling of transient flow in tubing and fracture propagation in reservoirs

Zhu

Dong

2022

Energy Science & Engineering

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Pulse injection can reduce the maximum operating pressure at the wellhead, which is conducive to solving the operational difficulties caused by the high breakdown pressure. The new injection mode causes a transient fluid flow in the tubing, and it interacts with the initiation and propagation of hydraulic fractures. However, there is still a lack of theoretical models to consider the above factors so that its mechanism cannot be explained. In this study, the transient flow model in the tubing was first established. Subsequently, the fracture propagation model was completed based on particle flow code (PFC). Moreover, the transient flow model was embedded into the PFC simulation software via its code script FISH. Finally, their coupled simulation model was established. Based on this model, the effects of injection flow rates on the fluid pressure in the tubing and the initiation and propagation of hydraulic fractures were discussed. Furthermore, the influence of parameters in the pulse injection scheme on the maximum wellhead pressure was studied by the orthogonal design method. The results show that with the increase of the injection flow rate, the fluid pressurization rate in the tubing and the fracture propagation rate both raise, which also causes a significant increase of the maximum wellhead pressure. Compared with a stable injection mode, pulse injection can evidently reduce the maximum wellhead pressure.The influence degree of each parameter on the maximum wellhead pressure in the pulse scheme is as follows: t 2 > Δq > Δt 4 > Δt 5 > Δt 3 . The research results of this paper have guiding significance for the engineering application and parameter design of pulse injection hydraulic fracturing.

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In-situ stresses, abnormal pore pressures and their impacts on the Triassic Xujiahe reservoirs in tectonically active western Sichuan basin

Cited by 23 publications

References 19 publications

In Situ Stress Prediction in Subsurface Rocks: An Overview and a New Method

In Situ Stress Prediction in Subsurface Rocks: An Overview and a New Method

Experimental Study on Compression and Torsion Fracture within 3D Printed Cementation-Weak and Porosity-High Sandstones

Pulse injection simulation based on the coupling of transient flow in tubing and fracture propagation in reservoirs

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