MULTISTAGE HYDRAULIC FRACTURING WITH PRODUCTION INTERVALS—A PROMISING TECHNOLOGY FOR RESERVOIRS SUBJECT TO REVERSE FAULTING STRESS REGIMES

2006 ◽  
Vol 46 (1) ◽  
pp. 89
Author(s):  
M.K. Rahman
Keyword(s):  
Stress State ◽  
Hydraulic Fracturing ◽  
Basic Mechanism ◽  
Deformation Analysis ◽  
Small Scale ◽  
Stress Regime ◽  
Induced Stress ◽  
Stress Changes ◽  
Reverse Faulting ◽  
Reservoir Conditions

The performance of hydraulic fracturing technology has not been so promising for some Australian tight-gas reservoirs. The existence of reverse faulting stress regimes (i.e. the vertical stress is the minimum one) in these reservoirs is found to be one reason among many others. Previous studies have established that the vertical hydraulic fracture initiated from a vertical well in a reverse faulting stress regime severely turns and twists to become horizontal while fracturing fluid is injected for further propagation of the fracture. This severely turned and twisted fracture impedes the fluid and proppant (engineered sand grains) injection and thus the fracturing job results in a short and constricted fracture. This is considered to be one of the major reasons for premature screen-outs that occur at extremely high-pressure on many occasions in the field, and the subsequent disappointingly low production rates. The aim of this paper is to present the results of an investigation with a model-scale gas reservoir to avoid this problem by carrying out the fracture treatments in a number of stages with production intervals. The basic mechanism that would allow the growth of a long, planar, productive fracture in such a manner is the production-induced stress change around the fracture tip. A simplified propped fracture configuration is modelled in a hypothetical small-scale reservoir with idealistic material properties. Production is simulated in time by varying different parameters and the production-induced stress changes are characterised by coupled fluid flow and deformation analysis. It is found from parametric results that the non-uniform reservoir pressure depletion induces a suitable stress state at the fracture tip for further planar propagation. The duration of production to induce the suitable stress state is found to be dependent on a number of parameters. The paper also highlights the implications and limitations of the concept for hydraulic fracturing in the mentioned reservoir conditions, and discussed further research directions.

scholarly journals Performance Evaluation of Enzyme Breaker for Fracturing Applications under Simulated Reservoir Conditions

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3133
Author(s):  
Yuling Meng ◽  
Fei Zhao ◽  
Xianwei Jin ◽  
Yun Feng ◽  
Gangzheng Sun ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Shear Resistance ◽  
Ammonium Persulfate ◽  
Fracturing Fluid ◽  
Medium Temperature ◽  
Fracture Conductivity ◽  
Wide Range ◽  
Reservoir Conditions ◽  
Alkaline Conditions ◽  
Resistance Performance

Fracturing fluids are being increasingly used for viscosity development and proppant transport during hydraulic fracturing operations. Furthermore, the breaker is an important additive in fracturing fluid to extensively degrade the polymer mass after fracturing operations, thereby maximizing fracture conductivity and minimizing residual damaging materials. In this study, the efficacy of different enzyme breakers was examined in alkaline and medium-temperature reservoirs. The parameters considered were the effect of the breaker on shear resistance performance and sand-suspending performance of the fracturing fluid, its damage to the reservoir after gel breaking, and its gel-breaking efficiency. The experimental results verified that mannanase II is an enzyme breaker with excellent gel-breaking performance at medium temperatures and alkaline conditions. In addition, mannanase II did not adversely affect the shear resistance performance and sand-suspending performance of the fracturing fluid during hydraulic fracturing. For the same gel-breaking result, the concentration of mannanase II used was only one fifth of other enzyme breakers (e.g., mannanase I, galactosidase, and amylase). Moreover, the amount of residue and the particle size of the residues generated were also significantly lower than those of the ammonium persulfate breaker. Finally, we also examined the viscosity-reducing capability of mannanase II under a wide range of temperatures (104–158 °F) and pH values (7–8.5) to recommend its best-use concentrations under different fracturing conditions. The mannanase has potential for applications in low-permeability oilfield development and to maximize long-term productivity from unconventional oilwells.

scholarly journals Numerical modeling of complex hydraulic fracture networks based on the discontinuous deformation analysis (DDA) method

2021 ◽  
pp. 014459872098153
Author(s):  
Yanzhi Hu ◽  
Xiao Li ◽  
Zhaobin Zhang ◽  
Jianming He ◽  
Guanfang Li
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Fracture Network ◽  
Discontinuous Deformation Analysis ◽  
Deformation Analysis ◽  
Fracture Networks ◽  
Proposed Model ◽  
Discontinuous Deformation ◽  
Shale Reservoirs ◽  
Dda Method

Hydraulic fracturing is one of the most important technologies for shale gas production. Complex hydraulic fracture networks can be stimulated in shale reservoirs due to the existence of numerous natural fractures. The prediction of the complex fracture network remains a difficult and challenging problem. This paper presents a fully coupled hydromechanical model for complex hydraulic fracture network propagation based on the discontinuous deformation analysis (DDA) method. In the proposed model, the fracture propagation and rock mass deformation are simulated under the framework of DDA, and the fluid flow within fractures is simulated using lubrication theory. In particular, the natural fracture network is considered by using the discrete fracture network (DFN) model. The proposed model is widely verified against several analytical and experimental results. All the numerical results show good agreement. Then, this model is applied to field-scale modeling of hydraulic fracturing in naturally fractured shale reservoirs. The simulation results show that the proposed model can capture the evolution process of complex hydraulic fracture networks. This work offers a feasible numerical tool for investigating hydraulic fracturing processes, which may be useful for optimizing the fracturing design of shale gas reservoirs.

Joint Application of Diagenetic, Petrophysical and Geomechanical Data for Selecting Hydraulic Fracturing Candidate Zone

2021 ◽  
Vol 8 ◽  
pp. 55-79
Author(s):  
E. Bakhshi ◽  
A. Shahrabadi ◽  
N. Golsanami ◽  
Sh. Seyedsajadi ◽  
X. Liu ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Pore Pressure ◽  
Earth Model ◽  
Reservoir Properties ◽  
Stress Regime ◽  
Geomechanical Properties ◽  
Hydrocarbon Reservoir ◽  
Diagenetic Processes ◽  
Mechanical Earth Model ◽  
New Equation

The more comprehensive information on the reservoir properties will help to better plan drilling and design production. Herein, diagenetic processes and geomechanical properties are notable parameters that determine reservoir quality. Recognizing the geomechanical properties of the reservoir as well as building a mechanical earth model play a strong role in the hydrocarbon reservoir life cycle and are key factors in analyzing wellbore instability, drilling operation optimization, and hydraulic fracturing designing operation. Therefore, the present study focuses on selecting the candidate zone for hydraulic fracturing through a novel approach that simultaneously considers the diagenetic, petrophysical, and geomechanical properties. The diagenetic processes were analyzed to determine the porosity types in the reservoir. After that, based on the laboratory test results for estimating reservoir petrophysical parameters, the zones with suitable reservoir properties were selected. Moreover, based on the reservoir geomechanical parameters and the constructed mechanical earth model, the best zones were selected for hydraulic fracturing operation in one of the Iranian fractured carbonate reservoirs. Finally, a new empirical equation for estimating pore pressure in nine zones of the studied well was developed. This equation provides a more precise estimation of stress profiles and thus leads to more accurate decision-making for candidate zone selection. Based on the results, vuggy porosity was the best porosity type, and zones C2, E2 and G2, having suitable values of porosity, permeability, and water saturation, showed good reservoir properties. Therefore, zone E2 and G2 were chosen as the candidate for hydraulic fracturing simulation based on their E (Young’s modulus) and ν (Poisson’s ratio) values. Based on the mechanical earth model and changes in the acoustic data versus depth, a new equation is introduced for calculating the pore pressure in the studied reservoir. According to the new equation, the dominant stress regime in the whole well, especially in the candidate zones, is SigHmax>SigV>Sighmin, while according to the pore pressure equation presented in the literature, the dominant stress regime in the studied well turns out to be SigHmax>Sighmin>SigV.  

Fluctuating Lake Levels in Rift Basins and its Impact on Extensional Tectonics

2021 ◽  
Author(s):  
April Allen Langhans ◽  
Robert Moucha ◽  
Michael Keith Paciga
Keyword(s):  
Stress State ◽  
Extensional Tectonics ◽  
Lake Levels ◽  
Rift Basins ◽  
Stress Changes ◽  
Response To Stress ◽  
Potential Impact ◽  
Extensional Model ◽  
Lithospheric Stress ◽  
Fully Coupled

<p>The feedback between climate driven processes; weathering, erosion, sediment transport, and deposition, and extensional tectonics is limited to a few studies (Burov and Cloething, 1997; Burov and Poliakov, 2001; Bialas and Buck, 2009; Theunissen and Huismans, 2019; Andrés-Martínez et al., 2019) despite these processes having been shown to impact the stress state and deformation along active orogens (Koons, 1989; Molnar and England, 1990; Avouac and Burov, 1996; Willett, 1999). Here we utilize a fully coupled landscape evolution and thermomechanical extensional model to investigate the potential impact on faulting and extension due to lake loading changes driven by changes in climate on processional timescales. Fault analyses focusing on heave, throw, and magnitude of dip on faults generated within each model are used to characterize individual faults response to stress changes and rift basin evolution. Preliminary results indicate that fluctuations in lake levels in response to climate change may impact the lithospheric stress state by changing both fault and basin geometries within an extensional basin.</p>

Coal Mine Hydraulic Fracturing Underground Drainage Research and Engineering Application

2017 ◽  
Vol 863 ◽  
pp. 334-341
Author(s):  
Jun Hui Fu ◽  
Guang Cai Wen ◽  
Fu Jin Lin ◽  
Hai Tao Sun ◽  
Ri Fu Li ◽  
...  
Keyword(s):  
Stress State ◽  
Hydraulic Fracturing ◽  
Coal Mine ◽  
Engineering Application ◽  
Fracture Morphology ◽  
Plane Stress State ◽  
Theoretical Formula ◽  
Test Results ◽  
Breakdown Pressure ◽  
Elastic Mechanics

Using elastic mechanics and fracture mechanics, analyzing the coal seam hydraulic fracturing breakdown pressure, given its theoretical formula. According to hydraulic fracturing stress status, given the form of two typical hydraulic fracture morphology. Analyzing hydraulic fracturing highly elliptical shape. The displacement field in plane stress state is given, and the theoretical formula of fracturing radius of hydraulic fracturing is deduced. The fracturing technology of underground fracturing is presented, and the fracturing location and fracturing parameters are determined. In Sihe Coal Mine conducted fracturing test, the test results showed that: the average of drainage volume of fracturing hole improved 4.4 times compared with non-pressed-hole. The extraction compliance time is reduced by 38%. Roadway tunneling speed was improved by 15%. It can solve the problem of gas overrun in roadway excavation well, and has a good application and popularization value.

Geomechanical Approach in Classification of Borehole Failures in Fractured Carbonates of Boca De Jaruco Field

2021 ◽  
Author(s):  
Anna Vladimirovna Norkina ◽  
Iaroslav Olegovich Simakov ◽  
Yuriy Anatoljevich Petrakov ◽  
Alexey Evgenjevich Sobolev ◽  
Oleg Vladimirovich Petrashov ◽  
...  
Keyword(s):  
Stress State ◽  
Horizontal Wells ◽  
Horizontal Stress ◽  
In Situ Stress ◽  
Vertical Wells ◽  
Stress Regime ◽  
Geophysical Information ◽  
The Republic ◽  
Maximum Horizontal Stress

Abstract This article is a continuation of the work on geomechanically calculations for optimizing the drilling of horizontal wells into the productive reservoir M at the Boca de Haruco field of the Republic of Cuba, presented in the article SPE-196897. As part of the work, an assessment of the stress state and direction was carried out using geological and geophysical information, an analysis of the pressure behavior during steam injections, cross-dipole acoustics, as well as oriented caliper data in vertical wells. After the completion of the first part of the work, the first horizontal wells were successfully drilled into the M formation. According to the recommendations, additional studies were carried out: core sampling and recording of micro-imager logging in the deviated sections. Presence of wellbore failures at the inclined sections allowed to use the method of inverse in-situ stress modeling based on image logs interpretation. The classification of wellbore failures by micro-imager logging: natural origin and violations of technogenic genesis is carried out. The type of breakout is defined. The result of the work was the determination of the stress state and horizontal stresses direction. In addition, the article is supplemented with the calculation of the maximum horizontal stress through the stress regime identifier factor.

Integrating Laboratory Testing and Numerical Modelling for a Giant Maturing Carbonate Field in UAE — II. Coupled Geomechanical Modelling of Stacked Reservoir Intervals

2021 ◽  
Author(s):  
Abdelwahab Noufal ◽  
Gaisoni Nasreldin ◽  
Faisal Al-Jenaibi ◽  
Joel Wesley Martin ◽  
Julian Guerra ◽  
...  
Keyword(s):  
Stress State ◽  
Oil And Gas ◽  
Water Injection ◽  
Seismic Inversion ◽  
Second Phase ◽  
High Porosity ◽  
Pore Collapse ◽  
Reservoir Compaction ◽  
Stress Changes ◽  
Field Management

Abstract A mature field located in a gently dipping structure onshore Abu Dhabi has multiple stacked oil and gas reservoirs experiencing different levels of depletion. The average reservoir pressure in some of these intervals had declined from the early production years to the present day by more than 2000 psi. Coupled geomechanical modelling is, therefore, of the greatest value to predict the stress paths in producing reservoir units, using the concept of effective stress. This paper examines the implications for long-term field management—focusing primarily on estimating the potential for reservoir compaction and predicting field subsidence. This paper takes the work reported in Noufal et al. (2020) one step further by integrating the results of a comprehensive geomechanical laboratory characterization study designed to assess the potential geomechanical changes in the stacked reservoirs from pre-production conditions to abandonment. This paper adopts a geomechanical modelling approach integrating a wide array of data—including prestack seismic inversion outputs and dynamic reservoir simulation results. This study comprised four phases. After the completion of rock mechanics testing, the first modelling phase examined geomechanics on a fine scale around individual wells. The goal of the second phase was to build 4D mechanical earth models (4D MEMs) by incorporating 14 reservoir models—resulting in one of the largest 4D MEMs ever built worldwide. The third phase involved determining the present-day stress state—matching calibrated post-production 1D MEMs and interpreted stress features. Lastly, the resulting model was used for field management and formation stimulation applications. The 4D geomechanical modelling results indicated stress changes in the order of several MPa in magnitude compared with the pre-production stress state, and some changes in stress orientations, especially in the vicinity of faults. This was validated using well images and direct stress measurements, indicating the ability of the 4D MEM to capture the changes in stress magnitudes and orientations caused by depletion. In the computed results, the 4D MEM captures the onset of pore collapse and its accelerating response as observed in the laboratory tests conducted on cores taken from different reservoir units. Pore collapse is predicted in later production years in areas with high porosity, and it is localized. The model highlights the influence of stress changes on porosity and permeability changes over time, thus providing insights into the planning of infill drilling and water injection. Qualitatively, the results provide invaluable insights into delineating potential sweet spots for stimulation by hydraulic fracturing.

SURFACE-LAYER SCALING FOR THE CONVECTION-INDUCED STRESS REGIME

1997 ◽  
Vol 83 (3) ◽  
pp. 423-439 ◽  
Author(s):  
A. A. GRACHEV ◽  
C. W. FAIRALL ◽  
S. S. ZILITINKEVICH
Keyword(s):  
Surface Layer ◽  
Stress Regime ◽  
Induced Stress
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