How sensitive is natural fracture permeability at depth to variation in effective stress

1993 ◽  
Vol 30 (3) ◽  
pp. A157
Keyword(s):  
Effective Stress ◽  
Natural Fracture ◽  
Fracture Permeability

scholarly journals Predictive Modelling of Naturally Fractured Reservoirs Using Geomechanics and Flow Simulation

GeoArabia ◽  
2001 ◽  
Vol 6 (1) ◽  
pp. 27-42
Author(s):  
Stephen J. Bourne ◽  
Lex Rijkels ◽  
Ben J. Stephenson ◽  
Emanuel J.M. Willemse
Keyword(s):  
Fractured Reservoirs ◽  
Flow Simulation ◽  
Naturally Fractured Reservoirs ◽  
Natural Fracture ◽  
Production Data ◽  
Well Test ◽  
Fracture Networks ◽  
Field Scale ◽  
Fracture Permeability ◽  
Naturally Fractured

ABSTRACT To optimise recovery in naturally fractured reservoirs, the field-scale distribution of fracture properties must be understood and quantified. We present a method to systematically predict the spatial distribution of natural fractures related to faulting and their effect on flow simulations. This approach yields field-scale models for the geometry and permeability of connected fracture networks. These are calibrated by geological, well test and field production data to constrain the distributions of fractures within the inter-well space. First, we calculate the stress distribution at the time of fracturing using the present-day structural reservoir geometry. This calculation is based on a geomechanical model of rock deformation that represents faults as frictionless surfaces within an isotropic homogeneous linear elastic medium. Second, the calculated stress field is used to govern the simulated growth of fracture networks. Finally, the fractures are upscaled dynamically by simulating flow through the discrete fracture network per grid block, enabling field-scale multi-phase reservoir simulation. Uncertainties associated with these predictions are considerably reduced as the model is constrained and validated by seismic, borehole, well test and production data. This approach is able to predict physically and geologically realistic fracture networks. Its successful application to outcrops and reservoirs demonstrates that there is a high degree of predictability in the properties of natural fracture networks. In cases of limited data, field-wide heterogeneity in fracture permeability can be modelled without the need for field-wide well coverage.

scholarly journals Effects of Slip Length and Inertia on the Permeability of Fracture with Slippery Boundary Condition

2020 ◽  
Vol 17 (11) ◽  
pp. 3817
Author(s):  
Benhua Liu ◽  
Hao Zhan ◽  
Yiran Liu ◽  
Huan Qi ◽  
Linxian Huang ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Boundary Condition ◽  
Recirculation Zone ◽  
Slip Length ◽  
Natural Fracture ◽  
Inertial Forces ◽  
Two Dimensional ◽  
Inertial Effects ◽  
Fracture Permeability ◽  
Evolution Path

Although the slippery boundary condition (BC) has been validated to enhance fracture permeability (k), the coupling effects of heterogeneous slippery BC and inertia on k remain less understood. We used computational fluid dynamics to investigate the competing roles of slippery BC and inertial forces in controlling k evolution with increasing pressure gradient by designing six cases with different slip length scenarios for a two-dimensional natural fracture. Our results suggest that pronounced inertial effects were directly related to and demonstrated by the growth of recirculation zone (RZ); this caused flow regimes transitioning from Darcy to non-Darcy and significantly reduced k, with an identical tailing slope for six cases, regardless of the variability in slip lengths. Moreover, the slippery BC dominantly determine the magnitude of k with orders depending on the slip length. Lastly, our study reveals that the specific k evolution path for the case with a varying slip length was significantly different from other cases with a homogeneous one, thus encouraging more efforts in determining the slip length for natural fractures via experiments.

A New Method of Optimization Design of Hydraulic Fracture Parameters in Low Porosity and Fractured Gas Reservoir

2013 ◽  
Vol 380-384 ◽  
pp. 1656-1659
Author(s):  
Xiu Ling Han ◽  
Fu Jian Zhou ◽  
Chun Ming Xiong ◽  
Xiong Fei Liu ◽  
Xian You Yang
Keyword(s):  
Simulation Model ◽  
Hydraulic Fracture ◽  
Optimization Design ◽  
Outer Part ◽  
Gas Production ◽  
Natural Fracture ◽  
Fracture Permeability ◽  
Gas Reservoir ◽  
Fracture Conductivity ◽  
High Production Rate

A new composite reservoir simulation model of lower computation cost was used to optimize hydraulic fracture length and fracture conductivity during performing a hydraulic fracturing. The simulation model is divided into inner part and outer part. The inner part is dual-porosity and dual-permeability system, and the other is single porosity system. The research shows that the natural fracture permeability and density are the most influential parameters; a relative long fracture with high hydraulic fracture conductivity is required for a high production rate due to non-Darcy flow effects. A shorter primary fracture is better in a gas reservoir of high natural density. The composite model represents the flow characteristic more accurately and provides the optimal design of fracturing treatments to obtain an economic gas production.

Effects of groundwater geochemistry on the permeability of grouted fractures

1984 ◽  
Vol 21 (1) ◽  
pp. 8-20 ◽  
Author(s):  
J. E. Gale ◽  
E. J. Reardon
Keyword(s):  
Fractured Rock ◽  
Confining Pressure ◽  
Natural Fracture ◽  
Geochemical Evolution ◽  
Fracture Plane ◽  
Fracture Permeability ◽  
Calcite Precipitation ◽  
Average Width ◽  
Physical Measurements ◽  
Oriented Parallel

A granite core containing a natural fracture, oriented parallel to the core axis, was collected, prepared, and its permeability measured in a hydrostatic test cell at different confining pressures. After the permeability hysteresis had been removed by several cycles of increasing and decreasing confining pressure, grout was placed within the fracture plane and allowed to cure for 40 days. Distilled water was forced through the sample until a significant flow rate developed. The influent solution for the sample was changed twice during the study to examine the effects of differing concentrations of Ca(HCO3)2 solutions on calcite precipitation within the fracture plane. The interaction of the Ca(HCO3)2 solution with the grout material resulted in a decrease in the permeability of the fracture plane over several months. At the close of the experiments, the sample was removed from the hydrostatic cell and opened along the fracture plane. The fracture exhibited two discrete braided channelways each with an average width of 2 mm. Precipitated calcite formed a rind along the walls of the channelways averaging 0.25 mm in thickness. The quantity of calcite precipitate determined from physical measurements was in reasonable agreement with that calculated using reaction rate expressions for calcite precipitation. The results of this study suggest the possibility that strategically located geochemical material could induce a geochemical evolution of groundwater within poorly grouted fractures, so as to decrease the permeability of the fractured rock system. Keywords: fracture permeability, grouted fractures, geochemistry, laboratory experiments, calcite precipitation.

Characterizing Natural-Fracture Permeability From Mud-Loss Data

SPE Journal ◽  
2010 ◽  
Vol 16 (01) ◽  
pp. 111-114 ◽  
Author(s):  
Jinsong Huang ◽  
D. V. Griffiths ◽  
Sau-Wai Wong
Keyword(s):  
Direct Method ◽  
Transient State ◽  
Natural Fracture ◽  
Curve Matching ◽  
Fracture Permeability ◽  
Type Curves ◽  
Cubic Equation ◽  
Matching Technique ◽  
Mud Loss ◽  
Insight Into

Summary Liétard et al. (1999, 2002) have provided important insight into the mechanism and prediction of transient-state radial mud invasion in the near-wellbore region. They provided type curves describing mud-loss volume vs. time that allow the hydraulic width of natural fractures to be estimated through a curve-matching technique. This paper describes a simpler and more direct method for estimating the hydraulic width by the solution of a cubic equation, with input parameters given by the well radius rw, the overpressure ratio Δp/τy, and the maximum mud loss volume (Vm)max.

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