ENHANCED PRODUCTION PRACTICES TO OPTIMIZE OUTPUT

Based on workshops sponsored by PTTC’s Central Gulf Region:

“Enhanced Production Methods Workshop” on June 24, 1998, in Lafayette, LA, and

“Optimization of Gas Well Completion and Production Practices” on March 30, 1999, New Orleans, LA

BOTTOM LINE

A periodic review of reservoir production practices and performance data, coupled with maintaining an awareness of newly developing technologies and techniques, is a good recipe for reservoir management success. Through production optimization methods, costs can be reduced and output increased.

PROBLEM ADDRESSED

With the prevailing low oil prices and continuing decline in production from aging domestic reservoirs, independent operators need low-risk techniques that can be implemented quickly and affordably. Moreover, it is important that improved production practices show a quick payout to increase well profitability and prolong field life.

KEY WORDS:

Reservoir Management, Production Optimization, Water Coning, Corrosion, Gas Lift, Submersible Pumps, Gas-Zone Completion

SPEAKERS

John McGowen, McGowen Working Partners

Chuck Schaub, Chevron USA

John McMullan, Louisiana State University

TECHNOLOGY OVERVIEW

The Holly Ridge field in Tensas Parish, Louisiana, had a 98% water cut: 40 wells produced 465 barrels of oil per day (bopd) and 90,000 barrels of water per day (bwpd). By examining and modifying practices, production costs were reduced, thus increasing profitability for the operator.

The rod pump integrity was improved by redesigning the pumps and maintaining constant standing-fluid levels, eliminating pump offs. A new gravel-pack design that maximized sand displaced in open-hole completions was implemented to control sand production and its inherent problems. Casing corrosion at the level of the shallow sands used to dispose of produced water was significantly reduced by eliminating water aeration (oxygenation) during surface handling. Pumping for produced-water disposal also was eliminated by swabbing and backwashing perforations during disposal well-completion. This created large behind-pipe voids that allowed gravity-flow disposal of the water.

In the area of the Ship Shoal field in the Gulf of Mexico, the goal was to reduce the production decline rate from 25% to 15% (750 bopd equivalent) at a cost of less than $1.00 per barrel. A similar goal was met in a nearby field by assigning an engineer to spend threefourths of his time monitoring production.

This approach involved:

(1) gathering information (including data on limitations of the facilities, pressure restrictions on gas lift wells, and well-flowing conditions identified by pressure tests and measurements of fluid levels)

(2) identifying the weakest links or bottlenecks in the production system,

(3) developing strategies to improve the weak links,

(4) implementing the strategies,

(5) evaluating the effectiveness of the strategies, and 

(6) repeating the process as necessary.

The following are typical examples of actions and results that were achieved in the Ship Shoal area:

• Added an additional outlet to increase water capaci-ty (cost: $25,000; increased production by 200 bopd).
• Changed the compressor loading (cost: $500; increased production by 250 bopd and 200 thousand cubic feet a day).
• Lowered discharge pressure on compressors (cost: $2,500; increased production by 300 bopd).
• Dropped the high-pressure gas well from a low-pressure bulk line. This lowered line pressure from 350 to 220 pounds per square inch (cost: $0; increased production by 150 bopd).
• Implemented a plastic job to shut off water (cost: $25,000; increased production by 250 bopd).
• Used an acid job (cost:$ 145,000: increased production by 1,500 bopd, and still producing 300 bopd higher one year later).

In total, 1,120 bopd of increased production, with a cumulative value of $6.5 million, was gained with a $257,000 investment. The decline rate was reduced to 14.2% at a cost of $0.63 per barrel of oil production added.

Electrical submersible pumps, relatively new to the Gulf of Mexico region, are making inroads in offshore applications where subsurface completions are required in 1,500-ft. depths. Savings are achieved because operators only need to lay a single flowline back to fixed platforms.

The use of high-strength metals (such as tungsten carbide for throats and diffusers instead of traditional stainless steel in down-hole jet pump applications) also can help reduce costs. Pumps with high-strength metals last twice as long in service as their predecessors and typically save $7,500 per well per year in avoided repair costs. The use of cyclone separators to separate solids from wellbore streams can further reduce repair costs.

Results from a reservoir simulation study comparing alternative approaches for completing and producing water-drive gas reservoirs indicate that using a perforated interval large enough to allow high production rates actually maximizes ultimate gas recovery, particularly in low-permeability reservoirs. This is contrary to the common practice of confining the perforations to the upper part of the productive interval and restricting the well production rate, which can actually result in reduced gas recovery and higher ultimate water production.

LESSONS LEARNED

Low-tech solutions aimed at reducing production costs or optimizing production procedures can increase profitability. In many cases, a careful review of current procedures and performance data may lead to multiple methods for increasing output, or cutting production costs, that can be implemented simultaneously.

CONNECTIONS:

Holly Ridge Field:
John McGowen
McGowen Working Partners
PO Box 55809, Jackson, MS 39216-4902
Phone 601-982-3444, Fax 601-982-1879

Ship Shoal Area:
Chuck Schaub, Chevron USA
PO Box 39100, Lafayette, LA 70503-5303
Phone 318-989-3000, Fax 318-989-3440

Coning Simulation Study:
John McMullan, Petroleum Engineering Dept.
Louisiana State University
CEBA Building, Rm. 3523 Baton Rouge, LA 70803
Phone 504-388-6040, Fax 504-388-5990

For information on PTTC’s Central Gulf Region and its activities contact:
Bob Baumann, Special Assistant to the Provost/ Energy Programs,
Louisiana State University, One East Fraternity Circle,
Baton Rouge, LA 70803-0301
Phone 225-388-4400, Fax 225-388-4541, E-mail rbaumann@lsu.edu

Disclaimer: No specific application of products or services is endorsed by PTTC. Reasonable steps are taken to ensure the reliability of sources for information that PTTC disseminates; individuals and institutions are solely responsible for the consequences of its use.

The not-for-profit Petroleum Technology Transfer Council is funded primarily by the US Department of Energy’s Office of Fossil Energy, with additional funding from universities, state geological surveys, several state governments, and industry donations.

Petroleum Technology Transfer Council, 2916 West T. C. Jester, Suite 103, Houston, TX 77018
Toll-free 1-888-THE-PTTC; Fax 713-688-0935; E-mail hq@pttc.org; web www.pttc.org