Assessment of Carboniferous Volcanic Horizontal Wells after Fracturing Based on Gray Correlation, Hierarchical Analysis and Fuzzy Evaluation

A comprehensive method to evaluate the factors affecting the production capacity of horizontal wells in Carboniferous volcanic rocks after fracturing is investigated. A systematic approach combining gray correlation analysis, hierarchical analysis and fuzzy evaluation is proposed. In particular, first the incidence of reservoir properties and fracturing parameters on production capacity is assessed. These parameters include reservoir base geological parameters (porosity, permeability, oil saturation, waterproof height) as well as engineering parameters (fracture half-length, fracture height, fracture conductivity, fracture distance). Afterwards, a two-by-two comparison judgment matrix of sensitive parameters is constructed by means of hierarchical analysis, and the weighting coefficients of the factors are determined, where oil saturation, fracture conductivity and fracture half-length are weighted higher. Finally, the horizontal wells in the target block are categorized in terms of production capacity based on the fuzzy evaluation method, and split accordingly into high-producing, relatively high-producing, medium-producing and low-producing wells. Such a categorization is intended to provide parametric guidance for reservoir fracturing and modification.