OPTIMIZING WELL PRODUCTION AND OPERATING EFFICIENCIES

Based on a workshop sponsored by PTTC’s Appalachian Region on March 23, 1999, in Columbus, OH.

BOTTOM LINE

Success in enhancing production and operating efficiency begins with the proper selection of candidate wells. Then it builds on field experience, and ends with effective supervision and innovation. Many technologies can be appropriate— the trick is identifying the technologies that best match the needs of the specific well.

PROBLEM ADDRESSED

For marginal wells, particularly natural gas wells, operating cost reductions can go only so far. To improve profitability, operators must also enhance production and operating efficiency by knowing how to identify and select candidate wells, evaluate the options for enhancing production, and implement those that are most attractive. Although not absolute, there are experience-based processes available to help operators reduce the risks involved.

KEY WORDS:

Production Monitoring, Hydraulic Fracturing, Stimulation Treatments, Re-completion Treatments, Well Candidate Selection

SPEAKERS

Increasing Production/ Profitability by Using Computer Monitoring Program:
Jerry James, James Engineering

Moving Domain Analysis for Drilling Candidates:
Joseph Franz, S. A. Holditch & Associates

How to Select the Best Re-stimulation Treatment:
Dan Pottmeyer, Producers Service Corp.

Well Testing to Determine Additional Gas Potential:
Greg Carder, Universal Well Services, Inc.

Production Enhancement Opportunities:
Jim Wing, Belden & Blake Corp.

Corporate Experience with No-Proppant Fracing:
Tim Altier, MB Operating Co.

Uphole Recompletions in Noble County, Ohio:
Kevin Smith, Oxford Oil Co.

TECHNOLOGY OVERVIEW

Optimizing production and operating efficiency involves four steps: establishing volumetric reserves, determining recovery factors, finding opportunities for enhancement (either production or reservoir), and developing an economic analysis of those opportunities.

“Priority,” a spreadsheet software program developed within a field project of the US Department of Energy’s Office of Fossil Energy, can help operators prioritize their field work. It compares actual production with forecast volumes, generating an exception list of underperforming wells. Reports continue to remind operators about under-performance until the problem is corrected, or the production goal is changed. The “Priority” program was used to monitor 250 wells in Ohio from late 1996 to early 1997. Total production increased 5.5% during these five months, as compared to a typical decline of 6% per year.

Moving Domain Analysis (MDA), a statistical approach for analyzing large data sets, evaluates localized domains of 10 to 15 wells. S. A. Holditch & Associates mapped production indicators using MDA, which helped identify wells that were potential re-stimulation candidates. Type curves were then prepared -another tool for identifying under-performing wells. Beginning in 1999, selected re-stimulation treatments will be performed to allow the selection process to be evaluated.

Profitable re-fracturing depends on selecting the right wells for re-stimulation candidates. If a well responded favorably to the initial frac treatment, it would probably respond well to a re-frac. It is important to find out if there was an abnormal, unexplained production decline. A review of the well’s history can assess whether it is near-wellbore damage (which may be amenable to chemical treatments) or whether stimulation is required.

Recently, the Independent Oil and Gas Association of New York, with funding from the New York State Energy Research and Development Authority, evaluated over 100 shut-in or marginal gas wells. Four tests were conducted: liquid-level analysis, estimated bottom-hole pressure, wireline service for total depth and water sample, and produced-water analysis. A high liquid level was the biggest problem— 49% of wells had over 100 ft. of liquid, and 23% had over 1,000 ft. About 20% of wells had fill over the perforations. Produced-water analysis showed that abnormal non-formation brines were not common.

Defying conventional wisdom, MB Operating Co. has profitably fraced wells without proppant for 30 years. When designing treatments for oil wells, the rule of thumb for water volume is 5,000 barrels. For gas wells, the volume is reduced to 3,000 to 4,000 barrels, based on expected depletion. The target pump rate for every job is 50 barrels per minute. This requires three pump trucks and a friction-reducer loading of 1/ 4 to 1/ 2 gallon per thousand gallons of water to pump down 4-inch casing. Water is filtered and always heated to 60 to 70 o F. After the frac job, the well is flowed back, then put on pump the next day. Frac water can be reused, but only a limited number of times, since bacterial problems can occur.

Oxford Oil Co. re-completed four depleted Clinton/ Medina wells in the Berea Sandstone. Although openhole logs were not available, cased-hole logs indicated that Berea was present. An open-hole log in a nearby well also indicated sufficient porosity. Oxford decided to re-complete one well, monitor its performance, then re-complete the others if the initial well succeeded.

The Baker Noon #1, which did not have the surface casing cemented through the Berea, was re-completed in 1992. The Clinton portion of the hole was plugged; the casing pulled, inspected and rerun, and the Berea zone perforated and stimulated with Oxford’s two-stage hydraulic fracture. The well open-flowed 377,000 cubic feet per day (mcfd) with a 24-hour shut-in pressure of 620 psi. Profitability was evident within a year, so the remaining three wells were re-completed in 1993. No problems were experienced when perforating through multiple casing strings. Completion zones were selected with Cased-Hole Neutron Logs run prior to perforating with two-or three-stage fracs.

The workover program paid out within 2 to 3 years, and the development cost was about $0.50 per mcf. With workover costs ($ 35,000) comprising about half of new well costs, the re-completion program was very attractive. Previously uneconomic Clinton/ Medina wells were turned from a liability into an asset.

CONNECTIONS:

Tim Altier, MB Operating Co.
104 6th St. NW, Canton, OH 44702
Phone 303-456-2454

Greg Carder, Universal Well Services, Inc.
PO Box 1456, Meadville, PA 16335
Phone 814-337-1115, Fax 814-337-5242

Joseph Franz, S. A. Holditch & Associates
1310 Commerce Dr.,
Park Ridge 1, Pittsburgh, PA 15275
Phone 814-337-1115, Fax 814-337-5242

Jerry James, President
James Engineering Inc.
231 3rd St., Marietta, OH 45750
Phone 740-373-9521

Dan Pottmeyer, Producers Service Corp.
109 S. Graham St., Box 2277 Zanesville, OH 43702
Phone 814-337-1115

Kevin Smith, Vice President
Oxford Oil Co.
4900 Boggs Rd., PO Box 2909 Zanesville, OH 43701
Phone 740-452-4503 x-235, Fax 740-452-4505, E-mail KsmithPE@aol.com

Larry Wickstrom, Geologist Supervisor
Petroleum Geology Group Ohio Geological Society
4383 Fountain Square Dr., Columbus, OH 43224
Phone 614-265-6598, Fax 614-447-1918, E-mail larry.wickstrom@dnr.state.oh.us

Jim Wing, Belden & Blake Corp.
5200 Stoneham Rd., NW PO Box 2500, N. Canton, OH 44720
Phone 330-499-1660, Fax 330-497-5470, E-mail jimwing@compuserve.com

For information on PTTC’s Appalachian Region and its activities contact:
Douglas Patchen, Program Director,
Appalachian Oil & Natural Gas Research Consortium
West Virginia University, NRCCE-Evansdale Dr.,
PO Box 6064 Morgantown, WV 26506-6064
Phone 304-293-2867 x-5443, Fax 304-293-7822, E-mail dpatch@wvunrcce.nrcce.wvu.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