Overcoming Open Hole Multistage Acid Fracturing Challenges in Saudi Arabian Carbonate Reservoirs with Swellable Packers, Best Practices and Dynamic Evaluation

Abstract

This paper describes the evolution of Open Hole (OH) Multi-Stage Fracture (MSF) completions that have been deployed in the Saudi Arabian tight gas carbonate reservoirs for the past several years. The carbonate reservoir in Saudi Arabia is often highly stressed and heterogeneous and fracturing treatment response can vary significantly between stages across the same reservoir.This paper also defines the best drilling and deployment practices of OH MSF completion with swellable packers, diagnostic technique of OH packer's integrity, acid fracturing strategies, and well performance of Saudi Arabian carbonate gas reservoirs. It is important to drill in the minimum stress direction so that transverse fractures can be induced. The swellable packers are to be set across good gauged section with optimum spacing between packers and fracture ports. The stimulation treatment designs need to be tailored with optimum fluid volume after evaluating the status of packer integrity between each acid fracturing treatment.Maintaining OH packer integrity between acid fracturing stages has become the most prevailing concern in emerging independent hydraulic fractures. Evident hydraulic communication between the stages through OH packers can develop a single dominant fracture affecting the well's sustainable gas rate as well as the recovery of final cumulative gas. The loss of annular isolation during fracturing with reactive fluids is often unavoidable in the presence of severe washout and unfavorable location of packers and fracture ports. Drilling in the minimum stress direction, inclusion of swellable packers, scrutinized depth selection of packers and fracture ports, dynamic evaluation of packer integrity between injections, detailed after-closure analysis, and vibrant optimization of acid stimulation treatments have increased effectiveness of acid stimulation and enhanced production.Even though fracturing treatments in low permeability oil and gas bearing sandstone formations are routinely executed in North America through OH Multi-Stage Fracturing completion to maximize stimulated reservoir volume, but it is not as common completion technique during acid fracturing treatments in the Carbonate gas reservoirs. This paper highlights unique challenges and recommendations for acid fracturing treatments in carbonate reservoirs through OH MSF completion.