Lower Tertiary - A Fully Comprehensive Well Completion Design Methodology to Overcome Reservoir Challenges

摘要

In developing an encompassing well completion design, an integrated, comprehensive solution study was under taken for the Lower Tertiary, mainly Wilcox Formation in the Gulf of Mexico. This included Reservoir Characterization, Optimized Hydraulic 3-D Fracture Design and Modeling, Nodal Analysis and Production Forecasting and Reservoir Simulation to determine the optimum well completion requirements in terms of tubing size internal diameter, completion tools inner string and downhole control valve sizes. Preliminary studies from the Wilcox Formation were taken into consideration and under the assumption of 3000 ft. MD gross height for the Wilcox formation, a representative LAS file containing the main curves for this formation was stretched out to have representative curves for the Gamma Ray, Resistivity, Neutron Porosity, Density, Sonic Delta Compressional and Values of Core Permeability. The pore pressure gradient and stress gradient was defined for each of the zones selected for stimulation. The stress profile was calculated considering the Gamma Ray Index and VShale on a per foot basis for the zones selected considering the Gamma Ray Curve and the assumed input values for the Sand and Shale. The mechanical properties were calculated from correlations for Vp and Vs utilizing the Vsh values as defined above, which in turn provided for determination of dynamic values for Young Modulus and Poisson on the same per foot basis. Additional calculations were performed to determine the static values of these same characteristics for each of the depths considered in the selected zones. The optimum well completion configuration was determined with the evaluation of: the fracture design (optimum treatment schedule for each zone) and minimizing the pressure losses in the production tubing. Well completion reservoir simulations assisting to estimate the flow velocity during the well life. The production system was designed to do not exceed the critical erosion velocity of the downhole equipment. This study assists in re-defining the well completion design requirements (maximum ratings) for ultra-deep water, high pressure and temperature applications.