Low permeability reservoirs are currently being propped with sand, resin coated sand, intermediate propped with sand, resin coated sand, intermediate density proppants and bauxite. This wide range of proppant cost and performance has resulted in the proppant cost and performance has resulted in the proliferation of proppant selection models. Initially, a rather vague relationship between well depth and proppant strength dictated the choice of proppant. More recently, computerized models of proppant. More recently, computerized models of varying complexity have become available which utilize net present value calculations. The input is based on the operator's performance goals for each well and specific reservoir properties. Simpler, non-computerized approaches also being used include cost/performance comparisons and nomographs. Each type of model, including several of the computerized models, will be examined.
Utilizing these models and net present value calculations, optimum fracturing treatment designs have been developed for low permeability reservoirs such as the Prue in Oklahoma. Typical well conditions are used in each of the selection models and the results are compared. The computerized models allow the operator to determine, prior to fracturing, how changes in proppant type, size, and quantity will affect post-frac production over time periods ranging from several months to many years. Thus the operator can choose the fracturing treatment design which best satisfies his economic performance goals for a particular well whether performance goals for a particular well whether those goals be long term or short term oriented.