Joint Meeting of the Rocky Mountain Petroleum Sections of AIME, 3–4 March, Denver

The F.I. process, recently developed by The Western Company of Midland, Tex., is the solution to a production problem as old as the fracturing process.

The F.I. or fracture initiation process creates a fracture in a subsurface formation at the exact depth and in the plane desired. This is accomplished in a two-step operation. First, the F.I. gun, shown in Fig. 1, is lowered to the desired depth and fired, creating six holes in opposing banks of three each. The specially designed jet perforators are housed in an expendable aluminum container. The gun is designed to withstand extreme conditions of pressure and temperature as well as field handling.

Upon firing, the portion of the gun extending below the necked-down mid-section is shattered while the massive section above, including the connecting thread, is retained in the firing sub and withdrawn from the well. If desired, the small amount of debris may be removed from the well with a sand pump, however, this is generally not objectionable and is left in the bottom of the hole.

The perforation pattern produced by the F.I. gun is shown in Fig. 2. Due to the tapering of jet perforations, the holes are converged slightly to maintain as nearly as possible a uniform ratio of hole diameter to web thickness. The reasons for this will be explained later. The diameter of the holes in 5 1/2in. casing is from 3/8 in. to 7/16 in. The holes are uniform and may be sealed with perforation ball sealers. No splitting of cemented casing has been experienced.

The second step in conducting an F.I. operation is that of hydraulic breakdown and extension of the fracture. The type of fluid used in the breakdown phase is important. We believe that pressurized fluid penetration into intrinsic fractures or planes of relative weakness could interfere with controlled breakdown. For this reason a non-penetrating type of fluid is recommended for the breakdown. The advantage gained by use of a non-penetrating fluid in fracture extension is generally understood.

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