Abstract
Abstract
Single phase retarded acid systems have been developed as an innovative approach to enhance well productivity. This acid system is designed to maximize contact with the formation by gradually releasing acid over time, which improves well stimulation, flowback initiation, and gas production. The technology involves using minimizing the free water to retard the reaction rate of the acid, which helps to distribute it homogeneously and deeper in the formation. In addition, this acid system can be combined with hydraulic fracturing to further improve production. The use of this innovative solution has shown to be effective in sustaining well productivity and could be a promising alternative to traditional acid systems such as emulsified acid.
The development of the new acid system involves blending a mineral acid with a suitable organic acid, while minimizing the presence of free water in the formulation. This approach helps to control the dissociation of the acid and achieve the desired retardation properties. The single-phase acid system, characterized by its low viscosity, has proven to be highly effective in acid fracturing applications. To assess its potential, the technology was implemented in high temperature and high-pressure conditions, specifically targeting the fracturing of conventional gas wells completed with a plug and perf completion consisting of six stages. The driving force behind field testing was the aim to significantly enhance the fracture half-length compared to the existing standard emulsified acid system. Achieving this objective involved careful control of engineering parameters during the treatment process, as well as optimizing the acid's retardation properties. A comprehensive post-treatment analysis was conducted to evaluate the performance of this acid system, comparing it to previously tested systems. This analysis included pressure transient analysis, post-frac flowback assessments, and friction pressure calculations. Downhole gauges were installed in order to obtain accurate pressure measurements for friction calculations and Pressure Build-up (PBU) analysis. We have recently shared significant progress in the development and implementation of an innovative engineered hybrid acid system, which effectively addresses the limitations associated with the use of emulsified acids. Implementing the new acid system in acid fracturing treatment, we have achieved remarkable success, as indicated by the sustained gas production rate. The treatment outcomes have resulted in a substantial enhancement of the well’ productivity index.
This paper presents a study showcasing the successful utilization of a newly developed retarded acid system for acid fracturing applications in multistage completions. It emphasizes the key design parameters unique to this system and outlines its advantages and limitations compared to traditional retarded acid system.