Sand jet perforating revisited

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 197 2. Unlike explosive perforating, which is literally a ''one shot" process, sand jet perforating uses a high velocity jet of abrasive fluid to cut thro ugh the casing, cement and deep into the formation, enabling pressure, pump ing time and other parameters to be varied to maximize penetration. Sand je ts can penetrate much deeper than explosives, and offer a cost-efficient, s afer and better-targeted alternative to hydraulic fracturing to bypassing d eep near-wellbore damage. This paper is based mainly on experience in Lithuania, where, in 1995, join t venture oil companies first started field operations to complete developm ent of small oil fields found in the west of the country (see Fig. 1) durin g 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 wi th heavy mud across open perforations, often for more than a decade. When i t proved impossible to get these wells to Bow again using (western) tubing conveyed explosive perforators (TCPs), sand jetting was used, as has been t he almost universal practice in Lithuania. The first well sand jet perforat ed by a joint venture company, which had yielded less than one barrel per d ay 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 bee n 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 B OPD. Though sand jet perforating is, at least theoretically, available from the main pumping contractors, it is almost unknown outside North America a nd the former Soviet Union, the main technical references (Refs. 1-5) being over 30 yr old. Sand jet perforating does, however, provide a cost-effecti ve means of passing deep formation damage and should form part of the armor y of any practicing petroleum engineer. This paper aims to remind engineers of this, review the technology and suggest appropriate applications.