Sand Jet Perforation (SJP) is a process which uses a high velocity jet of abrasive sand laden fluid to cut through the casing, cement and into the formation jetting pressure and cutting time can be varied to achieve maximum penetration.
The process begins by using Coiled Tubing to convey, accurately position and operate the sand jet perforating tool with integral casing collar locator (CCL). The sand jetting assembly perforates the zone; the CT is moved uphole to allow an optimum fracture treatment to be pumped down the casing/CT annulus. Based on the difference in depth of the perforation interval between the zones to be fractured, the underflush volume for fracturing treatment is calculated to place a sand plug in order to isolate the zone at the end of the treatment. If this is not sufficient, the sand used for perforating the next zone is allowed to settle to form additional plug height. An added advantage of using this technique includes washing off the extra sand (if any) using Coiled Tubing in the same run, which leads to saving significant amount of time and eliminates the need of setting up expensive packers to achieve zonal isolation in multi-zone wells.
With conventional wireline perforations, about 12 to 15 zones were usually fractured in a month in the Raniganj Coal Bed Methane (CBM) Block, India. The application of the above technology, made it possible to fracture more than 38 zones in a month. The process ensured that each zone received a positive zonal isolation and optimized fracturing treatment leading to cost effective and quality fracturing treatments.
This paper highlights the sand jetting perforation process for achieving maximum penetration, advantages of the technique for fracturing in CBM wells and the planning involved placing sand plugs for achieving optimized and economic stimulation treatment.