Pressure Losses in High Rate Well Flow Systems, Sassan Field, Persian Gulf, Iran
Authors: Byrne R.E. , Pakbaz E. 
Published: December 2007

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The information reported in this paper is part of a data gathering program by Lavan Petroleum Company to establish methods to increase the oil production from its existing wells and to aid in production from its existing wells and to aid in the design of future well flow systems. This program has consisted of pressure measurements at program has consisted of pressure measurements at accessible places in the flow systems of three high rate wells, with simultaneous recordings being made of the maximum producing rates. Variations in pressures and maximum rate have been measured with certain usual restrictions in place in the flow systems and with these place in the flow systems and with these restrictions reduced. Production rate increases of 2400 STB/D to 3000 STB/D resulted from eliminating restrictions in the systems.

Introduction

The maximum producing rates range between 20,075 and 27,216 stock tank barrels per day. Additional data from more precise observations will be available when the study has been concluded.

Modifications to the flow systems made recently were:

reduce the length of the downhole safety valve flow interval install a downhole safety valve having larger flow area in two wells and loop the wing valve flow configuration in another well.

In addition to the measured data reported here, the PVT analysis of the reservoir oil is also included. At reservoir conditions the oil is undersaturated. The three wells discussed here are completed in the same reservoir.

The Sassan wells are located in the Persian Gulf and vary in depth from about 70 feet to 100 feet. Each well has an individual well structure and is connected to a central flow station by either an 8-inch or a 10-inch flowline The wells all produce by natural flow.

The original completions were essentially the same, as shown on Figures 1 and 3. The 9 5/8" production string was cemented, and perforated production string was cemented, and perforated with 4 jet shots per foot. The producing zone (dolomite and limestone) was acidized. A dual packer was set at about 300 feet RKB with 2 3/8" packer was set at about 300 feet RKB with 2 3/8" tubing extending to near the top of the perforations and equipped with an injection valve one perforations and equipped with an injection valve one joint below the packer. The 3 1/2" string extends below the packer about 16 feet. It is equipped with a safety valve and flow nipple above the packer. The safety valve is kept open by packer. The safety valve is kept open by maintaining hydraulic pressure in the 3 1/2" tubing above the valve. The well fluid flows up the 9 5/8" × 2 3/8" annulus, then up the 3 1/2" tubing and through the ported nipple into the 9 5/8" × 3 1/2" × 2 3/8" annulus to the tubing spool, which has two 3" studded outlets at 45 deg.