Innovative Techniques for Efficient Wireline String Retrieval from Oil and Gas Well Rat Holes

Abstract

Abstract In the realm of oil and gas extraction, various well intervention techniques such as slickline, braided line, e-line, and coiled tubing are extensively utilized to maintain and optimize well productivity. Despite their widespread application, these techniques can encounter significant operational challenges. One such challenge is the accidental cutting of the wire at the top of the string, resulting in the string dropping into the rat hole. The difficulty of this situation is exacerbated when the outer diameter (OD) of the dropped string is smaller than the minimum restriction in the completion assembly. The rat hole, an extension of the wellbore below the completion tubing, is typically supported by casing sizes of 7 inches and 5 inches. Retrieving a lost string from a 7-inch casing presents a substantial challenge, particularly when using conventional pulling tools. These tools must have an OD not exceeding 2.55 inches to navigate through completion nipples, yet they often lack the capability to securely engage and retrieve objects from larger casing diameters. This paper introduces an innovative solution: a newly designed pulling tool equipped with an expandable skirt. This tool is engineered to overcome the aforementioned limitations by dynamically adjusting its OD, thereby facilitating the efficient retrieval of lost strings from the rat hole. The expandable skirt mechanism allows the tool to engage objects securely, ensuring successful retrieval operations. The development and deployment of this advanced tool not only enhance the efficiency of well intervention operations but also significantly contribute to maintaining well integrity. By addressing the critical issue of retrieving lost strings in challenging wellbore conditions, this tool extends the operational life of wells and reduces non-productive time. The paper provides a comprehensive overview of the design, functionality, and field application of this tool, demonstrating its potential to revolutionize well intervention practices in the oil and gas industry.