RIASSUNTO
ABSTRACT
In autumn 1991 AGIP concluded a test campaign on 3 in. Through Flow-Line (TFL) equipment, at a purpose-built test-site at Cortemaggiore, Italy. Testing included over 220 runs in a live onshore well, using a large number of different tools and functions.
TFL Side-Pocket Gas Lift and Jet Pump installation and operation techniques were also tested.
This article is a concise summary of the results and conclusions of the project.
Potential prospects for the future of TFL systems are evaluated in the light of present trends in offshore productiondevelopments and existing alternatives to TFL.
INTRODUCTION
Long-term .trials on 3 in. TFL equipment and procedures were run by AGIP for 3 years, at a test facility built for the purpose in Cortemaggiore, Italy (Figs. 1, 2). The site was set up next to an old, depleted oil well that had watered out and was recompleted to accommodate TFL for testing purposes (Fig. 3). Test operations were organized in two phases:
the preliminary phase (March 1988, April 1990) of tests on the surface,where the various tools and operations were tested in a short flow-line loop (280 m.) and in a horizontal mock-up TFL well completion;
the main phase (July 1990, June 1991), where the tools and operations weretested in the well.
OTC paper 6433 offers a thorough description of the test facilities, andsynthesizes the results from the preliminary phase of surface tests 1. The present article is the sequel to that first paper, and describes the second phase of the testing, performed in Well Corte 57.
Well and reservoir characteristics
A Residual Oil Saturation test performedin the Spring of 1990, just before the work-over to re-complete Well Corte 57 for TFL testing, yielded the following data:
Water Cut - 100 % approx.;
Salt concentration of formationwater - 210 gr/l;
Static BHP - 2767 psi;
Static THP - 41 psi;
Static BHT - 52°C;
P.I. - 1.4 (m3 /d)/(kg/cm2 );
Sand volume fraction - 1% approx.
The well completion specifications are as follows (Fig. 4):
vertical well;
Perforated interval = 1740 - 1745 m.;
Inner casing profile = 9 5/8 in. 1.0. to 1448 m.; 6 5/8 in. 1.0. liner from1047 m. to bottom.
The well completion is composed of a double TFL string, 3 1/2 in. * 3 1/2in., down to the depth of 1009 m., where an H-Member Cross-Over Head provides the lowest circulation point for TFL operations. Below this:
the ""primary"" string follows as a 3 1/2 in. TFL string down to the Foot-Valve (1029 m. depth), and, from there on, as a non-TFL single string to the perforations; a prepack screen is installed at the bottom of the string to protect TFL tools from sand;
the ""secondary"" string follows to the depth of 1017 m, where it ends with a No-Go type KN Landing Nipple.