Field Scale Modeling of Fracture Networks

Field Scale Modeling of Fracture Networks

Public Abstract

According to recent estimates, the U.S. domestic potential for fractured oil reservoirs is on the order of tens of billion of barrels. With domestic production depending more and more on mature fields, better technology for characterizing fracture flow paths, especially in deep, non-conventional plays and in carbonate rocks is key to producing hydrocarbons economically. Fracture transmissivity (or permeability) can enhance oil production, or on the other hand, result in early water breakthrough and consequently early well abandonment. However, spatial characteristics of the fracture system cannot be known deterministically for the subsurface reservoir. Instead, stochastic characterisation of fracture systems is usually attempted. Developing stochastic, field-scale model of fracture networks that are consistent with patterns observed on an outcrop, adhere to a physical basis for fracture propagation and honor field-specific observations is the objective of the proposed research.

The research objective will be completed in two phases. The initial step will use outcrop data to derive inputs for a fracture-mechanics-based fracture growth model. Outcrops of fracture networks in northwestern Wyoming will be used for this research because they contain well exposed, diverse fracture patterns in rock units that are oil and gas producers in the western United States. The outcrop pattern observed on the outcrop will be numerically simulated using a geomechanical model. This requires analysis of rock property data observed on the outcrop to derive inputs to the geomechanical model. A stochastic fracture prediction model that can replicate patterns in the geomechanical model will be developed. That model will extract the essence of the fracture pattern and then constrain stochastic models to reproduce the pattern characteristics.

Outcrops typically provide spatial variability information from a scale of few millimeters to kilometers. Geomechanical models can generate fracture patterns up to a length scale of 1 kilometer. In order to generate fracture patterns at a field scale (tens of kilometers), a unique calibration-based stochastic modeling approach is proposed. The calibration captures the uncertainty in fracture pattern due to uncertain rock characteristics and boundary conditions (layer geometry). The calibrated uncertainty will be used within a stochastic framework in order to simulate fracture networks.

The work is to be performed at the Center for Petroleum and Geosystems Engineering at The University of Texas at Austin. Cost-sharing is provided for 20% of the budget.


Contact:

Sanjay Srinivasan
Center for Petroleum and Geosystems Engineering
1 University Station C0304
The University of Texas at Austin
Austin, Texas 78712-0228
Phone: (512) 471-7218 FAX: (512) 471-9605
Email: ssriniva@mail.utexas.edu

See the Integrated Reservoir Characterization page for information on related research.