Hydraulic Fracture Modeling and Well Performance Analysis in CTD Wells Completed in Tight Sands

Abstract

The effective optimization of hydraulic fracture treatments in Coiled-Tubing Drilled (CTD) horizontal wells requires the integration of geomechanical modeling and properly designed hydraulic fracture treatments, including carefully selected stage and cluster placement. Tight sandstone reservoirs are often characterized by low productive potential due to low permeability, complex compartmentalization and limited reservoir energy resulting from low reservoir pressure. Well productivity may be optimized in both open-hole and cased-hole horizontal completions by minimizing the formation damage in these sandstone reservoirs through the application of true underbalanced CTD techniques, proper lateral configuration and optimized fracture stimulation design. In this study, geomechanical analyses were utilized to derive rock mechanical properties of tight sandstones, such as Young's Modulus and Poisson's Ratio using basic density, porosity and acoustic (compressional and shear) logs. General drilling experiences and mud weights were considered along with the logs to model pore pressure, overburden and horizontal stresses and a log-based minimum horizontal stress was calculated. The estimated in-situ stress and rock mechanical properties from the geomechanical model were used to investigate the pressures necessary to create hydraulic fractures in the tight sandstones and their propagation direction, in order to improve the flow capacity. Hydraulic fracturing models were developed to identify fracture geometry parameters (length, height, width, conductivity and permeability) for horizontal CTD wells in tight sandstones. Well performance analysis was performed to estimate potential production rates from CTD wells having various lateral lengths and numbers of frac stages by minimizing formation damage through true underbalanced CTD techniques and optimized stimulation design. Effective horizontal lateral length was determined as the combined length of each stage that was successfully treated. Modeling the open-hole and cased-hole multistage completion systems in the tight sandstones indicates longer laterals and an increased number of available stages are desirable to increase production. Our models suggest that a successful, efficient completion may be achieved in tight sandstone reservoirs through the application of true underbalanced CTD techniques coupled with optimized lateral geometry and fracture stimulation design.