Relationship Between Fracture Propagation Pressure And Pore Pressure

1977 ◽  
Author(s):  
L.B. Salz
Keyword(s):  
Pore Pressure ◽  
Fracture Propagation

Geomechanical Controls on Frac-Hits

2022 ◽  
Author(s):  
Dharmendra Kumar ◽  
Ahmad Ghassemi
Keyword(s):  
Pore Pressure ◽  
Fracture Propagation ◽  
Horizontal Wells ◽  
Operational Parameters ◽  
Modeling And Analysis ◽  
Matrix Deformation ◽  
In Situ Conditions ◽  
Fracture Fluid ◽  
Poroelastic Model ◽  
Element Method

Abstract The communication among the horizontal wells or "frac-hits" issue have been reported in several field observations. These observations show that the "infill" well fractures could have a tendency to propagate towards the "parent" well depending on reservoir in-situ conditions and operational parameters. Drilling the horizontal wells in a "staggered" layout with both horizontal and vertical offset could be a mitigation strategy to prevent the "frac-hits" issue. In this study, we present a detailed geomechanical modeling and analysis of the proposed solution. For numerical modeling, we used our state-of-the-art fully coupled poroelastic model "GeoFrac-3D" which is based on the boundary element method for the rock matrix deformation/fracture propagation and the finite element method for the fracture fluid flow. The "GeoFrac-3D" simulator fully couples pore pressure to stresses and allows for dynamic modeling of production/injection and fracture propagation. The simulation results demonstrate that production from a "parent’ well causes a non-uniform reduction of the reservoir pore pressure around the production fractures, resulting in an anisotropic decrease of the reservoir total stresses, which could affect fracture propagation from the "infill" wells. We examine the optimal orientation and position of the "infill" well based on the numerical analysis to reduce the "frac-hits" issue in the horizontal well refracturing. The posibility of "frac-hits" can be reduced by optimizing the direction and locations of the "infill" wells, as well as re-pressurizing the "parent" well. The results suggest that arranging the horizontal wells in a "staggered" or "wine rack" arrangement decreases direct well interference and could increase the drainage volume.

SURFACE CASING DESIGN CONSIDERATIONS WITH EMPHASIS ON THE BASS BASIN

1987 ◽  
Vol 27 (1) ◽  
pp. 363
Author(s):  
P.H. Winchester
Keyword(s):  
Pore Pressure ◽  
Fracture Propagation ◽  
Propagation Theory ◽  
Pressure Testing ◽  
Design Considerations ◽  
Worked Example ◽  
Blowout Preventer ◽  
Casing Pressure ◽  
Volume Estimates ◽  
Effective Design

The main purpose of surface casing and the associated blowout preventer (BOP) system is to contain any well pressure that may be encountered while drilling to total depth or the next casing depth. Not only does this mean that the casing and BOP should be sufficient to withstand the pressure exerted upon them, but also the depth of the casing shoe should be such that the formation will not break down under the influence of this pressure. The latter condition could lead to an internal blowout and subsequent cratering to surface.Design consideration for surface casing must encompass fracture propagation theory, pore pressure and kick volume estimates, and associated casing pressure calculations. A worked example from the Bass Basin gives a safe and effective design when these are applied.These design considerations also have an impact on the procedures for pressure testing casing, BOP, and formation which are valid when compared with the existing statutory requirements of Australia, Norway and the USA.Although the operator is responsible for correct casing design, the various statutory bodies have a role to technically challenge and modify drilling and casing programs, and the procedures outlined give the foundations on which to build an acceptable casing scheme.

scholarly journals Using Cohesive Zone Model to Simulate the Hydraulic Fracture Interaction with Natural Fracture in Poro-Viscoelastic Formation

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1254 ◽  
Author(s):  
Yu Suo ◽  
Zhixi Chen ◽  
Hao Yan ◽  
Daobing Wang ◽  
Yun Zhang
Keyword(s):  
Numerical Model ◽  
Pore Pressure ◽  
Hydraulic Fracture ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Fracture Propagation ◽  
Natural Fracture ◽  
Zone Model ◽  
Fluid Viscosity ◽  
Fluid Diffusion

Hydraulic fracturing is a widely used production stimulation technology for conventional and unconventional reservoirs. The cohesive element is used to explain the tip fracture process. In this paper, the cohesive zone model was used to simulate hydraulic fracture initiation and propagation at the same time rock deformation and fluid exchange. A numerical model for fracture propagation in poro-viscoelastic formation is considered. In this numerical model, we incorporate the pore-pressure effect by coupling fluid diffusion with shale matrix viscoelasticity. The numerical procedure for hydraulically driven fracture propagation uses a poro-viscoelasticity theory to describe the fluid diffusion and matrix creep in the solid skeleton, in conjunction with pore-pressure cohesive zone model and ABAQUS was used as a platform for the numerical simulation. The simulation results are compared with the available solutions in the literature. The higher the approaching angle, the higher the differential stress, tensile stress difference, injection rate, and injection fluid viscosity, and it will be easier for hydraulic fracture crossing natural fracture. These results could provide theoretical guidance for predicting the generation of fracture network and gain a better understanding of deformational behavior of shale when fracturing.

Investigation of Water Leakoff Considering the Component Variation and Gas Entrapment in Shale During Hydraulic-Fracturing Stimulation

2016 ◽  
Vol 19 (03) ◽  
pp. 511-519 ◽  
Author(s):  
Junjian Wang ◽  
Sheik S. Rahman
Keyword(s):  
Hydraulic Fracturing ◽  
Pore Pressure ◽  
Shale Gas ◽  
Mathematical Formulation ◽  
Fracture Propagation ◽  
Water Displacement ◽  
Gas Reservoir ◽  
Capillary Effects ◽  
Shale Gas Reservoir ◽  
Gas Entrapment

Summary The water leakoff into the shale matrix during the hydraulic-fracture treatment has been a critical issue in determining fracture geometry. Furthermore, water leakoff also affects mechanical properties of the surrounding rock matrix which, in turn, affects fracture propagation. Conventional approaches for the prediction of leakoff were inadequate because several important phenomena are ignored. In this paper, several effects on water leakoff into shale matrix during shale-gas reservoir stimulation are considered. A simplified structure is used to depict the complex pore network in shale. Different interactive forces involved in water displacement considering the osmotic and capillary effects are taken into account in the mathematical formulation of the model. The proposed numerical model is used to study the water leakoff and the consequent pressure increase caused by gas entrapment. The potential influence of the increase in pore pressure on the generation of microfractures is also discussed. The simulation results show reasonable agreement with the previous studies, and indicate that the water leakoff greatly depends on composition and structure of shale matrix. Clay minerals, for example, are naturally prone to water invasion, and draw water faster than hydrophilic minerals and organic matter because of the osmotic effect. Furthermore, the invaded water significantly increases the pore pressure within the shale matrix because of gas entrapment, which leads to a strong nonlinear relationship between leakoff and the square root of time. An increase in pore pressure also results in a decrease in effective stress that leads to the generation of tension-induced microfractures in shale matrix. This study emphasizes the significance of osmotic and capillary effects as well as gas entrapment on hydraulic-fracturing treatment of shale-gas reservoirs. Moreover, the new leakoff model can be applied to assist the investigation of fracture-propagation behavior in a shale-gas reservoir.

Effects of non-uniform pore pressure field on hydraulic fracture propagation behaviors

2019 ◽  
Vol 221 ◽  
pp. 106682 ◽  
Author(s):  
Qi Gao ◽  
Songcai Han ◽  
Yuanfang Cheng ◽  
Chuanliang Yan ◽  
Yuanwei Sun ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Hydraulic Fracture ◽  
Pressure Field ◽  
Fracture Propagation ◽  
Hydraulic Fracture Propagation
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