Some influences of stratigraphy and structure on reservoir stress orientation

Geophysics ◽  
1994 ◽  
Vol 59 (6) ◽  
pp. 954-962 ◽  
Author(s):  
Michael S. Bruno ◽  
Don F. Winterstein
Keyword(s):  
Principal Stress ◽  
Compressive Stress ◽  
Horizontal Stress ◽  
Oil Fields ◽  
Fold Axis ◽  
Principal Stresses ◽  
Stress Orientation ◽  
Stress Direction ◽  
Well Pattern ◽  
Maximum Horizontal Stress

The azimuth of maximum horizontal stress in a reservoir can vary significantly with depth and with position on a subsurface structure. We present and discuss evidence from field data for such variation and demonstrate both analytically and with finite‐element modeling how such changes might take place. Under boundary conditions of uniform far‐field displacement, changes in stratigraphic layering can reorient the principal stress direction if the formation is intrinsically anisotropic. If the formation stiffness is lower perpendicular to bedding than parallel to bedding (as is often the case in layered geologic media), an increase in dip will reduce the component of compressive stress in the dip azimuth direction. Folds can reorient principal stresses because flexural strain varies with depth and position. Compressive stress perpendicular to a fold axis increases with depth at the crest of an anticline and decreases with depth at the limb. When the regional stress anisotropy is weak, this change in stress magnitude can reorient the local principal stress directions. Numerical simulations of such effects gave results consistent with changes in stress orientation at the Cymric and Lost Hills oil fields in California as observed via shear‐wave polarization analyses and tiltmeter surveys of hydraulic fracturing. Knowledge of such variation of stress direction with depth and structural position is critical for drilling, completions, hydraulic fracture, and well pattern designs.

Horizontal Water Injection Wells: Injectivity and Containment of Injection-Induced Fractures

2021 ◽  
Author(s):  
Jongsoo Hwang ◽  
Mukul Sharma ◽  
Maria-Magdalena Chiotoroiu ◽  
Torsten Clemens
Keyword(s):  
Horizontal Well ◽  
Water Injection ◽  
Fracture Initiation ◽  
Horizontal Stress ◽  
Operating Conditions ◽  
Critical Factors ◽  
Injection Wells ◽  
Stress Direction ◽  
Maximum Horizontal Stress ◽  
Transverse Fractures

Abstract Horizontal water injection wells have the capacity to inject larger volumes of water and have a smaller surface footprint than vertical wells. We present a new quantitative analysis on horizontal well injectivity, injection scheme (matrix vs. fracturing), and fracture containment. To precisely predict injector performance and delineate safe operating conditions, we simulate particle plugging, thermo-poro-elastic stress changes, thermal convection and conduction and fracture growth/containment in reservoirs with multiple layers. Simulation results show that matrix injection in horizontal wells continues over a longer time than vertical injectors as the particle deposition occurs slowly on the larger surface area of horizontal wellbores. At the same time, heat loss occurs uniformly over a longer wellbore length to cause less thermal stress reduction and delay fracture initiation. As a result, the horizontal well length and the injection rates are critical factors that control fracture initiation and long-term injectivity of horizontal injectors. To predict fracture containment accurately, thermal conduction in the caprock and associated thermal stresses are found to be critical factors. We show that ignoring these factors underestimates fracture height growth. Based on our simulation analysis, we suggest strategies to maintain high injectivity and delay fracture initiation by controlling the injection rate, temperature, and water quality. We also provide several methods to design horizontal water injectors to improve fracture containment considering wellbore orientation relative to the local stress orientations. Well placement in the local maximum horizontal stress direction induces longitudinal fractures with better containment and less fracture turning than transverse fractures. When the well is drilled perpendicular to the maximum horizontal stress direction, the initiation of transverse fractures is delayed compared with the longitudinal case. Flow control devices are recommended to segment the flow rate and the wellbore. This helps to ensure uniform water placement and helps to keep the fractures contained.

scholarly journals Verification of Fracture Reorientation and Analysis of Influence Factors in Multiple Fracturing Treatment

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Mingjing Lu ◽  
Yuliang Su ◽  
Marte Gutierrez ◽  
Yaohua Zhan ◽  
Kai Chen ◽  
...  
Keyword(s):  
Pressure Difference ◽  
Research Result ◽  
Influence Factors ◽  
Injection Pressure ◽  
Horizontal Stress ◽  
Initial Stresses ◽  
True Triaxial ◽  
Triaxial Apparatus ◽  
Well Pattern ◽  
Maximum Horizontal Stress

A fracture will be initiated and propagated along the direction of maximum horizontal stress in fracturing treatment; however, in refracturing stimulation, the new fracture may be initiated and propagated along a different direction from the initial one. This is defined as a fracture reorientation. It is difficult to predict fracture reorientation due to the variation of formation properties after long-term production. To verify the existence of fracture reorientation and analyze its influencing factors in multiple fracturing treatment, experimental and numerical simulations are presented in this paper. Firstly, multiple fracturing stimulation is carried out with a self-assembled large true triaxial apparatus, and the fracture reorientation is successfully induced by changing the injection pressure and initial stresses in multiple fracturing processes. Then, numerical coupled hydromechanical modeling of the actual field production and injection well pattern is performed. In particular, the stress reversal region, which indicates the distance of fracture reorientation, and the factors that influence the reorientation are analyzed. The laboratory experiment and numerical simulation results show that the fracture reoriented angle obtained can be perpendicular to the initial fracture. Stress field and formation pressure are the two main factors that influence the fracture reorientation. With higher pressure differences and lower initial horizontal stress differences, the area in which it is possible to initiate reoriented fracture will be larger. The fractures of wells in the early production stage are hard to reorient due to the high formation and borehole pressure difference, and the fracture reorientation area will be expanded until the pressure difference is low to a certain value. This research result can guide oilfield stimulation treatments.

scholarly journals Determination of horizontal stress orientation in the areas of the Tomsk region

2021 ◽  
Vol 1 (7) ◽  
pp. 16-24
Author(s):  
Anton E. Antonov ◽  
◽  
Andrei S. Shadrin ◽  
Dmitrii V. Konoshonkin ◽  
Valerii S. Rukavishnikov ◽  
...  
Keyword(s):  
Horizontal Stress ◽  
Summary Table ◽  
Average Value ◽  
The North ◽  
Stress Orientation ◽  
Tomsk Region ◽  
Stress Orientations ◽  
Borehole Breakouts ◽  
Minimum Stress ◽  
Maximum Horizontal Stress

Introduction. The World Stress Map project proves that horizontal stress orientation determination is a global task essential for the majority of geomechanical calculations. However, there is scant data on stress orientations in the territory of Russia at the moment. The task is therefore highly relevant. Research objective is to determine the orientations of maximum and minimum horizontal stresses by separate areas of the Tomsk region and build a map of horizontal stresses. Method of research. The basis for determining the orientations of horizontal stresses is the theory of drilling-induced fracture and borehole breakouts occurrence. The maximum stress orientation coincides with the drilling-induced fracture orientation, whereas the minimum stress orientation coincides with the borehole breakouts orientation or is perpendicular to the maximum stresses. Results. Research results are compiled in a summary table containing mean orientations of horizontal stresses by areas and a map of horizontal stress orientations. Conclusions. A summary map of maximum horizontal stress strike azimuths has been constructed. The stresses are of similar orientation in every well under consideration, except for a well in the North-Shingin area. The average value of maximum horizontal stress orientation has made up 337° northwest and 157° southeast.

scholarly journals Dike Propagation During Global Contraction: Making Sense of Conflicting Stress Histories on Mercury

2021 ◽  
Vol 9 ◽  
Author(s):  
Kelsey Crane ◽  
Allison Bohanon
Keyword(s):  
Physical Model ◽  
Compressive Stress ◽  
Propagation Distance ◽  
Flood Basalt ◽  
Horizontal Stress ◽  
Principal Stresses ◽  
Stress Regime ◽  
Making Sense ◽  
Griffith Criterion ◽  
Uppermost Layer

Thrust fault-related landforms, smooth plains units, and impact craters and basins have all been observed on the surface of Mercury. While tectonic landforms point to a long-lived history of global cooling and contraction, smooth plains units have been inferred to represent more punctuated periods of effusive volcanism. The timings of these processes are inferred through impact cratering records to have overlapped, yet the stress regimes implied by the processes are contradictory. Effusive volcanism on Mercury is believed to have produced flood basalts through dikes, the propagation of which is dependent on being able to open and fill vertical tensile cracks when horizontal stresses are small. On the contrary, thrust faults propagate when at least one horizontal stress is very large relative to the vertical compressive stress. We made sense of conflicting stress regimes through modeling with frictional faulting theory and Earth analogue work. Frictional faulting theory equations predict that the minimum and maximum principal stresses have a predictable relationship when thrust faulting is observed. The Griffith Criterion and Kirsch equations similarly predict a relationship between these stresses when tensile fractures are observed. Together, both sets of equations limit the range of stresses possible when dikes and thrusts are observed and permitted us to calculate deviatoric stresses for regions of Earth and Mercury. Deviatoric stress was applied to test a physical model for dike propagation distance in the horizontally compressive stress regime of the Columbia River Flood Basalt Province, an Earth analogue for Borealis Planitia, the northern smooth plains, of Mercury. By confirming that dike propagation distances from sources observed in the province can be generated with the physical model, we confidently apply the model to confirm that dikes on Mercury can propagate in a horizontally compressive stress regime and calculate the depth to the source for the plains materials. Results imply that dikes could travel from ∼89 km depth to bring material from deep within the lithosphere to the surface, and that Mercury’s lithosphere is mechanically layered, with only the uppermost layer being weak.

scholarly journals Study on In Situ Stress Distribution Law of the Deep Mine: Taking Linyi Mining Area as an Example

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xuelong Li ◽  
Shaojie Chen ◽  
Sheng Wang ◽  
Meng Zhao ◽  
Hui Liu
Keyword(s):  
Coal Mine ◽  
Mining Area ◽  
Horizontal Stress ◽  
Geological Structure ◽  
In Situ Stress ◽  
Distribution Law ◽  
Principal Stresses ◽  
Stress Regime ◽  
Maximum Horizontal Stress

The variation of the in situ stress state is closely related to various factors. In situ stress state is also an important indicator to guide mining production. The study of in situ stress measurement and its distribution characteristics has always been a basic and very important work in mine production. In this study, the deep mines of Linyi Mining Area were considered as the research object. In this regard, the stress distribution law of each mine was studied. We found that the relationship between principal stresses was σH >  σ v  > σh, which belongs to the strike-slip stress regime. In this stress regime, the lateral Earth pressure coefficient was greater than one, and the magnitude of the three principal stresses all showed an increasing trend with the increase of depth. The maximum horizontal stress direction of the Gucheng Coal Mine, Guotun Coal Mine, and Pengzhuang Coal Mine was NW-SE under the influence of regional geological structure, while the maximum horizontal stress direction of Wanglou Coal Mine was NE-SW under the influence of local geological structure. Besides, the relationship between mine in situ stress and mine geological structure, the impact of original rock stress on stope stability, and the effect of original rock stress on floor water inrushing were also investigated. We believe that the research results are beneficial to mine disaster prevention and safety production.

Stress orientations from borehole wall fractures with examples from Colorado, east Texas, and northern Canada

1982 ◽  
Vol 19 (7) ◽  
pp. 1358-1370 ◽  
Author(s):  
D. I. Gough ◽  
J. S. Bell
Keyword(s):  
Principal Stress ◽  
Structural Evolution ◽  
Horizontal Stress ◽  
Hydraulic Fractures ◽  
Mechanism Analysis ◽  
East Texas ◽  
Principal Stresses ◽  
Northern Canada ◽  
East Texas Basin ◽  
Stress Orientations

Azimuthally aligned breakouts in oil wells are explained as shear fractures in the zone of amplified stress difference near the borehole, in a stress field having unequal horizontal principal stresses. Brittle fracture theory, on the Mohr–Coulomb failure criterion, shows that the fractures will propagate from the wall and cause wide spalled zones observable with the four-arm dipmeter. In homogeneous rock, breakouts formed in this way should lengthen the diameter by no more than 8–10%. The breakouts occur near the ends of the diameter parallel to the smaller horizontal stress. Tensile fractures may occur in the orthogonal azimuth, but are unlikely to be seen by the four-arm dipmeter calipers.Three examples are given of principal stress orientations inferred from borehole breakouts. At Rangely, Colorado, breakout azimuths suggest an approximately east–west principal compression in agreement with results obtained previously from direct stress measurements, hydrofracture, and earthquake mechanism analysis. In the east Texas Basin, north-northwest to northwest aligned breakouts suggest maximum horizontal stresses oriented at right angles to these directions. This is consistent with inferences from recent extensional faulting and one hydraulic fracture determination. In the Norman Wells area of northern Canada, northwest–southeast aligned breakouts suggest a contemporary horizontal principal compression closely parallel to natural, probably hydraulic fractures of Laramide age in a subsurface limestone reservoir. The inferred principal stress axes are consistent with the structural evolution of this area, and extend the evidence for coherent stress orientation in western Canada from southern Alberta to Norman Wells, a distance of 1900 km.

Tunnel Ground Stress Test and Rock Burst Prediction Based on Hydraulic Fracturing Method

2013 ◽  
Vol 368-370 ◽  
pp. 1830-1837
Author(s):  
Xin Zhe Li ◽  
Geng Feng Wang ◽  
Jun Mei Li
Keyword(s):  
Hydraulic Fracturing ◽  
Rock Burst ◽  
Stress Test ◽  
Large Angle ◽  
Horizontal Stress ◽  
Stress Direction ◽  
Ground Stress ◽  
The Stability ◽  
Minimum Horizontal Stress ◽  
Maximum Horizontal Stress

The hydraulic fracturing method is a common method to measure the ground stress. This article describes the principles of the hydraulic fracturing method, studies the distribution and the value of the ground stress in a tunnel area with the hydraulic fracturing method, and predicts rock burst by using the Russenes discriminance and the Turchaninov discriminance. The results show that the maximum horizontal stress is between 4.7MPa and 11.1MPa, and the minimum horizontal stress is between 4.0MPa and 8.0MPa. The maximum horizontal stress direction of the drilling is between N63 °W and N72 °W, and it is not conducive to the stability of the tunnel surrounding rocks because the large angle intersection of the tunnel axis direction and the maximum horizontal stress direction.

Inversion of Full Waveform Sonic Data Assists Calibration of Geomechanics Model

2021 ◽  
Vol 73 (09) ◽  
pp. 39-40
Author(s):  
Chris Carpenter
Keyword(s):  
Oil And Gas ◽  
Horizontal Stress ◽  
Gas Storage ◽  
Asia Pacific ◽  
Earth Model ◽  
Numerical Representation ◽  
Principal Stresses ◽  
Geomechanical Properties ◽  
Full Waveform ◽  
Maximum Horizontal Stress

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 202260, “Inversion of Advanced Full Waveform Sonic Data Provides Magnitudes of Minimum and Maximum Horizontal Stress for Calibrating the Geomechanics Model in a Gas Storage Reservoir,” by Zachariah J. Pallikathekathil, SPE, Xing Wang Yang, and Saeed Hafezy, Schlumberger, et al., prepared for the 2020 SPE Asia Pacific Oil and Gas Conference and Exhibition, originally scheduled to be held in Perth, Australia, 20–22 October. The paper has not been peer reviewed. In 1D geomechanics projects, calibration of stress is extremely important in the construction of a valid mechanical earth model (MEM). The effective minimum horizontal stress (Shmin) data usually are available from traditional measurements, but these have a few deficiencies. The complete paper presents a technique for deriving stresses in which the radial variation of acoustic velocity from an advanced dipole sonic logging tool is inverted to obtain stress. These derived stresses are then used to calibrate the 1D MEM for a gas storage field. Regional Geology The field is in the Otway Basin in Western Victoria. Gas is trapped in the Late Cretaceous Waarre formation at depths between 1155 and 1200 m subsea. The reservoir is sealed by the overlying marine Belfast mudstone, which is the common seal in the stratigraphy across the onshore Otway Basin. The reservoir has excellent reservoir quality and has proved ideal for gas storage. Challenge Posed by the 1D MEM Challenge Posed by the 1D MEM Well 1 was recently drilled in the basin. A 1D MEM - a numerical representation of the geomechanical properties and stress state of the earth at any depth - was planned to be constructed to obtain the current-day far-field principal stresses (Shmin), effective maximum horizontal stress (SHmax), and effective vertical stress (SV)] in the Belfast and Waarre formations. Understanding the stress field was important, especially in the caprock (Belfast) and in the reservoir (Waarre) so that the pressure limits for safe gas-storage operation could be defined better. However, for a variety of reasons, no conventional stress measurements were available to calibrate the modeled stress in the 1D MEM. Without any calibration of the stress, the geomechanics model would feature high uncertainty to be used to define the pressure operational limits for gas-storage operation. Fortunately, a new wireline sonic tool was recorded in the reservoir section and the overburden sections of the borehole in Well 1. A quick dispersion analysis of the waveforms showed that the Paaratte formation, above the Belfast formation, was acoustically stress-sensitive and that advanced processing could be performed to invert the acoustic information to stress values.

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