Advances In Sand Jet Perforating

Abstract

Abstract Sand jet perforating (SJP) is a process that uses high pressure fluid slurry to perforate tubulars and cement within an oil or gas well, and simultaneously extend a cavity into the reservoir. SJP has its origins in the 1960s with many large scale commercial successes in several international venues. While the SJP process was a technical success at that time, it was not an economic success. Few advancements in technology were attempted until the late 1990s. Advances in metallurgy have allowed major re-designs of sand jet perforating tools and jet orifices. These advances coupled with improvements in pump liner design have made SJP more cost effective today. The use of coiled tubing as a conveyance method further allows fluid pressures to be increased, and higher pressure limits make the SJP process even more effective. Newer modular SJP tool designs ensure near limitless re-configuration of coiled tubing conveyed plugs, packers, hold-down tools, perforation, and fracturing tools for simultaneous use during completion and work-over operations. Applications for Sand Jet Perforating technology include perforation and re-perforation of vertical and horizontal oil and gas wells and perforation and treatment of coal bed methane wells. SJP can also be used in conjunction with other technologies such as fresh water and foam fracturing and for enhanced performance resulting from chemical injection and acidization. Sand Jet Perforating provides an alternative to widely accepted wire-line or tubing conveyed explosive methods used in most fields today. Hundreds of documented successes are available to confirm that SJP increases communication between well bore and reservoir more effectively with less formation damage and is accomplished in fewer round trips in and out of the well bore than more widely used perforating methods. Added benefits are realized as perforating and fracturing can be accomplished nearly simultaneously with a common work string. Several papers and studies have recently been published that document the many benefits of Sand Jet Perforating, and recent demand for these services is increasing. This paper discusses the benefits of using Sand Jet Perforating tools and explains some new designs that suggest a broader range of uses. History The Authors' first discovery of documented use of Sand Jet Perforating was in 1939 when it was attempted as an outgrowth of acid jetting techniques. Similarly, our first discovery of any technical papers began to surface in the early 1960s and included discussions of theoretical explanations (power, fluid and particle velocity, and the effects of different variables on cutting ability and penetration); field observations and techniques; as well as uses of the technology with other established treatment methods (i.e. hydraulic fracturing). Engineers and operators involved in the early field work observed promise for this budding technology and the different ways that it could be used. By 1961, it is estimated that more than 5,000 jobs using the process had been performed with a success ratio of over 90 percent. These applications included casing perforation, open hole jetting, slotting, and cutting tubulars. It was noted that the perforations produced large burr-free holes in resident casing with very desirable penetration and cavity formation. This information begs the question, "Why did the sand jet perforating process seem to stop in the late 1960's when it had such promising future?" The answer lies in a combination of factors. One obstacle that these jetting pioneers faced was the very limited life of the equipment. The working life of SJP tools was measured in minutes as the abrasive fluid degraded the inner diameter of the tooling much the same way it cut through the targeted casing. Although carbide wear parts appeared in the 1960's, extended life and alternative wear materials were largely unavailable or non-existent. The sand slurry also had to be pumped at significantly high pressure and flow which could damage pumps or, at a minimum, require frequent maintenance to valves, valve seats, pump pistons, and pump liners. Another contributing factor to the lack of acceptance of abrasive jet perforating was the wide array of newer explosive/shaped charge perforating which replaced the older bullet perforating methods.