Effectiveness Evaluation Of Natural Fracture In Xuer Gas Reservoir In Xinchang Area

The Xuer gas reservoir is a very low pore and permeable reservoir with itsdensity lithology.This reservoir has experienced many tectonic movements since fromIndochina period in Chuanxi depression. These movements made its folds and faultsbecome complex. Amont of fractures of this reservoir are great benefit of thepermeabilite of gas. So, it’s necessary to analyze and evaluate the effectiveness ofnatural fracture for finding the benefit areas and formulating development programs.In this article, I summaried the character and forming stages of natural fracture，besed on achievement of the exploration, development and preliminary research.Ianalysed the effectiveness of natural fracture in view of static and dynamic.Iinterpreted the effectiveness of natural fracture based on the well testing andproduction performance, corrected the opening of imaging logging, and corrected theopening and permeability of conventional logging using the result of imaging loggingand Three-dimensional CT Scanning. Through the analysis of the outcrop observation,drilling core, and logging data, I considered that the extent of fracture was controlledof lithologies, the tectonic deformation, thick, depth, state of regional tectonic stress.The affect of faults to fracture is greatly deep. Based on the experiment and imaginglogging, I considered the opening of fracture was controlled of fracture occurrence,fracture surface features, pressure, depth, state of regional tectonic stress. I built themethods and indicators of quantitative evaluations with the extent and the opening offracture for the effectiveness of fracture system of wells and ereas. The indicator forwell fracture system is composed of the fracture frequency and the fracture openingfrom conventional logging. The indicator for area fracture system is composed of theextent and the opening of fracture with the parameters is calculated from the ancientand modern regional tectonic stress simulation. Compare the indicator for wellfracture system and area fracture system to the production of well test, I set up astandard to divided the wells and areas into several categories.