Comprehensive Formation Evaluation of HF Carbonate Reservoir by Integrating the Static and Dynamic Parameters

Abstract

Abstract This paper presents some new laboratory parameters and a process to describe and characterize the low permeability carbonate reservoir. The objective is to provide a method integrating both static and dynamic data with the physical rock properties for low-permeability reservoirs. Based on the laboratory experiments by using the mercury injection capillary pressure (MICP), nuclear magnetic resonance (NMR), relative permeability curves and physical simulation experiments of core samples, the pore microstructure features of low permeability carbonate reservoir and its influence on the formation petrophysics were analyzed. New formation evaluation parameters for low permeability carbonate reservoir are proposed involving mean pore-throat radius, movable oil saturation and threshold pressure gradient. Results of the MICP indicated that there mainly 6 type pore-throat distribution. Good exponentiation interrelationship between permeability and the mean pore- throat radius. Results of core flooding experiments indicated that the pore structure have eminent influence on the threshold pressure gradient. Results indicate that there are good relationship between the movable fluid saturation and the permeability. New parameter had been proposed to identify the fluid mobility such as irreducible water, movable oil and residual oil. Results show that moving oil saturation should be an assessment indicator to water drive oil well. Nonlinear flow would occur and reduce deliverability in low permeability reservoir. Incorporated with petrophysics, mean-pore throat radius, threshold pressure gradient and movable fluid saturation a comprehensive evaluation method has beenestablished. According to this method, reservoirs can be classified into 4 types. Results indicatedthat the new parameters and method presented in this paper would have broad application prospect ingeological selection area techniques and well effective spacing evaluation for the development of low permeability carbonate reservoirs.