Production modelling of idealized naturally fractured reservoirs intersected by horizontal wellbores.

摘要

A systematic methodology for optimization of hydrocarbon recovery from naturally fractured reservoirs exploited by horizontal wells has been developed. The procedure involves reservoir characterization, inflow performance analysis (IPR), production forecasting and subsequent economic evaluation.; Techniques for characterizing naturally fractured reservoirs are developed by integrating various methods from different disciplines. The permeability tensors for some fracture patterns defined from geologic analysis have been analytically derived assuming infinite, smooth and parallel fractures. Procedures have also been proposed for more sophisticated and elegant fracture analysis including statistical representations of fracture characteristics, stochastic and geostatistical simulations of fracture geometry, and numerical calculations of permeability tensors assuming finite fractures.; Analytical single phase and multiphase pseudo-steady state inflow performance equations of a horizontal well intersecting natural fractures are derived. The effects of matrix permeability anisotropy, wellbore eccentricity, non-Darcy flow phenomena, and fracture characteristics are considered. These inflow equations provide a relatively simple engineering basis for evaluating horizontal well productivity in naturally fractured reservoirs.; Based on material balance analyses and linear approximations of reservoir fluid properties as functions of reservoir pressure, new semi analytical methods have been derived for predicting the future production performance of naturally fractured oil and gas reservoirs intersected by horizontal wells.; An economic evaluation model has been developed for assessing the feasibility of exploiting naturally fractured reservoirs using horizontal well technology. Detailed equations for estimating the cost, profit, and return on investment for producing a hydrocarbon reservoir are derived.; The methodology developed in this study was implemented on a computer and may be used to forecast the future production performance, and to perform the economic and IPR analyses of naturally fractured reservoirs intersected by horizontal wells for any drilling scenario, fracture characteristics, combinations of reservoir rock and fluid properties. A case study indicates that the developed technology shows great usefulness in identifying the optimal schemes in horizontal well drilling, production planning, and reservoir management in the hydrocarbon recovery optimization from naturally fractured reservoirs. It offers the advantages of sophisticated reservoir simulators and yet the simplicity of analytical approaches.