Improved Reservoir Description from Pressure Transients

Abstract

Abstract This paper describes an innovative approach to integrate pressure transients with numerical reservoir simulation models. The derivative plot, from analytical Pressure Transient Analysis, is used to aid history match pressure transients measurements directly into the production history matched numerical reservoir simulation model. Most often only the extrapolated pressure is explicitly (as a single point measure) incorporated for history matching the reservoir material balance. Characterization of heterogeneity and complex reservoir features such as barriers, and aquifers are subjectively incorporated or inferred in the simulation model from analytical solutions. Furthermore analytical techniques cannot account for all geometrical descriptions and are limited at describing multiphase flow and well interference. This methodology expands on traditional reservoir simulation history matching by incorporating a stepwise approach in matching geological features on an already built conventional reservoir simulation model. An actual field example is discussed to illustrate on how this methodology populates properties away from the wellbore in terms of grid blocks based on the pressure diffusion regimes of the derivative plot rather than using averaged terms such as the analytical radius of investigation or matching it in a Cartesian plot. It consists of adjusting the simulation model sequentially: wellbore storage, near wellbore permeability (kh and skin), permeability away from the wellbore and boundaries to match the complete spectrum of the observed pressure derivative. Additional field examples illustrate the benefits of this methodology in the context of a multi-well development scenario: The presence of a gas injector that was initially interpreted as a closed boundary and the expected interference response between multiple producing wells. With this approach an improved description and reduced uncertainty is obtained for the reservoir simulation model, providing a more accurate production forecast to estimate reserves, optimize the reservoir management plan and/or to evaluate additional development scenarios.