Sand Jet Perforating Revisited

Abstract

Summary Though sand jet perforating is not a new technique, it is one that has been almost forgotten, the last SPE paper on the subject being published in 1972. Unlike explosive perforating, which is literally a "one shot" process, sand jet perforating uses a high velocity jet of abrasive fluid to cut through the casing, cement and deep into the formation, enabling pressure, pumping time and other parameters to be varied to maximize penetration. Sand jets can penetrate much deeper than explosives, and offer a cost-efficient, safer and better-targeted alternative to hydraulic fracturing to bypassing deep near-wellbore damage. This paper is based mainly on experience in Lithuania, where, in 1995, joint venture oil companies first started field operations to complete development of small oil fields found in the west of the country (see Fig. 1) during the Soviet era, but which had been considered as too small to develop for the Soviet Union, with giant oil fields to the east. Wells, some of which had produced on test at over one thousand barrels per day, had been left with heavy mud across open perforations, often for more than a decade. When it proved impossible to get these wells to flow again using (western) tubing conveyed explosive perforators (TCPs), sand jetting was used, as has been the almost universal practice in Lithuania. The first well sand jet perforated by a joint venture company, which had yielded less than one barrel per day with (western) TCPs, gave over 900 barrels per day when perforated with sand jets. Subsequently, one of the best producers in Lithuania, which had already been sand jetted once, was reperforated using more advanced techniques. Coiled tubing was run through the xmas tree and completion to enable the well to be sand jet perforated, with oil as the carrier fluid, underbalanced, with the well flowing throughout, resulting in a doubling of production to 800 BOPD. Though sand jet perforating is, at least theoretically, available from the main pumping contractors, it is almost unknown outside North America and the former Soviet Union, the main technical references (Refs. 1–5) being over 30 yr old. Sand jet perforating does, however, provide a cost-effective means of passing deep formation damage and should form part of the armory of any practicing petroleum engineer. This paper aims to remind engineers of this, review the technology and suggest appropriate applications.