Placement of Stimulating Fluids in Multilayered Carbonate Reservoirs

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 166184, ’Achieving Optimum Placement of Stimulating Fluids in Multilayered Carbonate Reservoirs: A Novel Approach,’ by Pierre Ramondenc, SPE, Bruno Lecerf, and Philippe M.J. Tardy, SPE, Schlumberger, prepared for the 2013 SPE Annual Technical Conference and Exhibition, New Orleans, 30 September- 2 October. The paper has not been peer reviewed. This paper presents an alternative approach to designing and executing matrix-stimulation treatments in multilayered carbonate reservoirs. The proposed workflow does not rely on damage skin by layer during the design and the execution phases of the treatment. It instead requires a step of determining where the acid must be injected, and at which rate and volume, to meet an objective function. The workflow presented here allows decoupling the questions of optimal placement of a fluid for a given well, the performance of the materials selected, and the treatment schedule considered. Introduction Because acid dissolves carbonate formation without damaging reactions, the main challenge in acidizing multilayered carbonate reservoirs is to achieve optimum placement of the stimulating fluid. Heterogeneities such as the inherent dual porosity, high permeability contrasts of carbonate rocks, variable extent of damage, presence of natural fractures, or existence of differential pressure between reservoir layers—which can sometimes feature very large heights or lengths—tend to affect the fluid-injection profile. The uncertainty and often limited knowledge of those various parameters usually complicate the design of carbonate-acidizing treatments, whose outcome very much depends on how well the rock and damage characteristics have been taken into account when selecting the stimulation fluids and how and where those fluids will be pumped into the formation.