Computing Estimated Values of Optimal Fracture Half Length in the Tight Gas Sand Advisor Program

Abstract

AbstractProducing natural gas from Tight Gas Sand (TGS) reservoirs is currently very important to the industry in North America and will be of increasing importance to the global energy industry in the coming decades. We are developing a TGS Advisory system to provide advice to engineers evaluating and developing tight gas sand reservoirs. The program can be used to establish best practices for drilling, completing, stimulating and producing a TGS reservoir as a function of the reservoir properties. We have combined knowledge from the petroleum literature and interviews with experts with detailed calculations to build TGS Advisor.One of the most important problems for TGS reservoirs is to determine the optimum fracture half-length as a function of the reservoir properties. In this paper, we will describe three methods to calculate the optimum fracture half length, which include using 2-D fracture design equations, the unified fracture design method, and a rule-of-thumb method using the values of formation permeability and expected drainage area. With these three estimated values of optimum fracture half-length, the user can confidently use a 3-D or Pseudo 3-D fracture design model to generate the more detailed fracture treatment design. All the three methods have been incorporated into the TGS Advisory system. An example of using TGS Advisor to estimate the optimal fracture half-length will be presented.