Chevron U.K. Ltd. has set back to back North Sea depth records and is claiming a world record for electric submersible pump (ESP) installations in Ninian field.
Pump design and installation was done by CUK Aberdeen Petroleum Engineering in conjunction with Lasalle Ltd., Inverurie, Scotland.
Well C49 was completed last March with a Reda 540 series, 99 stage GN7000 pump with a 225 hp motor. The pump was installed at a North Sea record depth of 12,960 ft measured depth (MD), 9,088 ft true vertical depth (TVD). C49 was placed on production Mar. 31 and is producing 4,116 b/d of oil and 13 b/d of water.
Well C18Z broke that record last May, with a setting depth of 14,874 ft MD. Its unit is a Reda 540, 176 stage GN7000 pump with a 300 hp motor. This installation also set world records as the deepest vertical offshore ESP at 9,279 ft TVD and the longest run of ESP cable.
C18Z was placed on production on May 17. Its current production is 3,921 b/d of oil and 1,680 b/d of water.
Most Ninian field wells flow naturally, supported by large volumes of water injected for pressure support. However, several flank wells receive only limited pressure support due to faulting and permeability barriers and require ESPs or other methods of artificial lift.
A CHANGE IN SETTING
Previous ESP completions traditionally had been set inside the 91/8 in. casing due to tight clearances and to allow for installation of a bypass logging assembly.
By running into the 7 in. liner the pumps can be set about 3,000 vertical ft deeper, achieving 50-60% higher production rates because of the greater reservoir drawdown that can be achieved.
Clearances are improved by crossing over to 3 1/2 in. tubing and flat cable in the 7 in. section. The bypass logging tool is eliminated.
Both installations involved running the pump assemblies through 91/8 in. by 7 in. liner laps at high deviation angles.
Due to difficulties encountered on the first attempt to enter the liner, the pump assembly for C18Z was specially modified and configured to provide maximum protection to the electrical cable during installation.
RENTAL ARRANGEMENT
The C18Z installation is the first Chevron completion run under a results based rental agreement.
This is a vendor partnering arrangement in which Lasalle provided design engineering, equipment, and installation services up front and continues to monitor pump performance. Lasalle and Reda bore the capital equipment costs and retain ownership. They are reimbursed on a rental basis as long as the pump is serviceable.
Under this arrangement Lasalle/Reda assume a portion of the risk of early failure and receive added payment if the pump has a greater than average run life.
Copyright 1990 Oil & Gas Journal. All Rights Reserved.