Integrated Interpretation of Interwell Connectivity Using Injection and Production Fluctuations

摘要

A method to characterize reservoirs, based on matching temporal fluctuations in injection and production rates, has recently been developed. The method produces two coefficients for each injector-producer pair; one parameter, lambda, quantifies the connectivity and the other, tau, quantifies the fluid storage in the vicinity of the pair. Previous analyses used lambda and tau separately to infer the presence of transmissibility barriers and conduits in the reservoir, but several common conditions could not be easily distinguished. This paper describes how lambda and tau can be jointly interpreted to enhance inference about preferential transmissibility trends and barriers. Two different combinations are useful: one is a plot of log (lambda) versus log (tau) for a producer and nearby injectors, and the second is a Lorenz-style flow capacity (F) versus storativity (C) plot. These techniques were tested against the results of a numerical simulator and applied to data from the North Buck Draw field. Using the simulated data, we find that the F-C plots and the lambda-tau plots are capable of identifying whether the connectivity of an injector-producer well pair is through fractures, a high-permeability layer, multiple-layers or through partially completed wells. Analysis of data from the North Buck Draw field shows a reasonable correspondence between tau and the tracer breakthrough times. Of two possible geological models for Buck Draw, the F-C and lambda-tau plots support the model that has less connectivity in the field. The wells in fluvial deposits show better communication than those wells in more estuarine-dominated regions.