Abstract

Bed-normal fractures or joints are common in sedimentary basins (reservoirs). Fracture spacing S is an important parameter affecting both the mechanical stability and permeability of rock masses. Many studies have focused on predicting this parameter from the bed thickness T. Field measurements do show that S and T are related but frequently in a very nonlinear way so that at T > T0, S stabilizes at a certain value S0. Both T0 and S0 strongly vary in different settings. To understand this S(T) relationship, we conducted 2-D finite-difference modeling of a three-stratigraphic-layer system, where interfaces between competent and incompetent layers have different shear strength values τ. The models reproduce not only a general trend of the S(T) dependence in nature but also the observed variability of T0 and S0. These parameters are controlled in the models mostly by τ. T0 and S0 rapidly decrease with the τ increase, but the ratio T0/S0 ≈ 1.5 remains constant. At small T, the S(T) curves are linear, with slopes κ, whose reciprocal (1/κ) is linearly related to τ and increases with τ increase. The strong nonlinearity of S(T) relationship is explained by the T-dependence of the fracturing process obtained in the models.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.