Pushing the Limits of Distributed Temperature Survey Analysis in Mega-Reach Power Water Injectors

Abstract

Increases in well complexity and stimulation challenges have led to more complicated stimulations. The challenge that consistently arises after conceptually designing the treatment is how to determine the zonal coverage and evaluate the stimulation, especially in extended reach wells in carbonate reservoirs. Significant effort has been spent on using modern technologies to qualitatively evaluate zonal coverage and estimate the skin factor evolvement after the treatment. No work has yet answered the following question: How does matrix acidizing alter near-wellbore permeability and affect the zonation of the wellbore when treating carbonate reservoirs?In long horizontal wells that are drilled in carbonate formations, it is believed that wormholing significantly alters the near-wellbore apparent permeability. Nevertheless, methods to estimate the change in permeability resulting from a matrix treatment are not known, and usually the change is accounted for in simulators by assigning a very low skin value. Other work conducted in carbonate reservoirs using pressure transient analysis (PTA) techniques has shown that applying a change in permeability is necessary to obtain a type-curve match.This paper presents an innovative workflow and algorithm to estimate the changes in the critical matrix rock properties and how to incorporate these changes into further simulation. The algorithm integrates the while drilling mobility data, open hole porosity logs, pressure transient data, distributed temperature survey data, and production logging data to verify the accuracy of the model by using the flow rate as the control parameter for iterations.A case study shows how we could derive a flow profile for the pre-stimulation stage, optimize matrix stimulation treatments in real time according to the formation response and diversion efficiency, define reservoir zones that are contributing to flow before and after the treatment, and finally, estimate new values of permeability and skin to be utilized in post-treatment reservoir simulations.