Tech Transfer Track

Ultralight Proppant Field Experience

Serving the market where ultralight proppants are required, BJ Services (BJ) makes two LiteProp Proppants available: (1) a 1.25 specific gravity product being a resin-coated walnut shell with 5,000 psi crush rating and (2) a 1.75 specific gravity product being ceramic beads formed from a porous substrate and resin-coated with 8,000 psi crush rating. There is a temperature limit of 225-275 °F.

BJ reports performing more than a dozen LiteProp fracs in Canada. There it has shown good results with gas-energized systems in underpressured formations. Underpressuring is common in mature areas with production from several different depths. BJ has performed several hundred LiteProp fracs in the Permian Basin. Citing experience in a waterflood infill project (producers and injectors), BJ notes that LiteProp enabled fracing to cover 74% more surface area in the productive zone, achieved more than a three-fold increase in conductivity, and reduced the 60-day production decline rate from 61% to 34%.

Conventional Ottawa sand proppants have a specific gravity in the range of 2.7 and a crush rating around 5,000 psi. Resin coating, which can increase cost three to five times, reduces proppant flowback, improves particle uniformity and increases crush resistance to about 8,000 psi. Ceramic beads, costing four to five times as much as Ottawa sand, can withstand up to 10,000 psi closure pressure and can also be resin-coated.

Excerpted from "Proppant Progress," New Technology Magazine, April/May 2005, pp. 12-14. For more information, contact BJ Services Canada's Brad Rieb, 403-531-2522, Brieb@bjservices.
ca.

Energy Advocates
 2005 Awards

During it's recent "International Energy Policy Conference" in Denver, the Energy Advocates recognized the following 2005 award winners:

Individual—Larry Nichols, Devon Energy
Corporate Sherman Smith—Schlumberger
Lifetime Achievement—June Brooks, Jack Graves & Lee Keeling
Community—Chesapeake Energy Corporation
Outstanding Association—AAPG

Since 1974, The Energy Advocates (www.energyadvocates.org) have been committed to sharing the truth on energy issues.

Horizontal Underbalanced Experience

Underbalanced (UB) drilling is becoming an important tool for developing producing horizons in underpressured reservoirs, partially depleted fields, new fields and sensitive zones. In Canada there is a longer history with UB operations with several fields now having several years of production data. Weatherford recently analyzed these fields, comparing underbalanced horizontal with conventional wells. All analyses were based on production data only because flowing pressures were unavailable. Arps' decline curve analysis was chosen for forecasting. Since the Arps' method is only valid during boundary-dominated flow, data were first checked with Fetkovich type curves to confirm that boundary-dominated flow existed. Economic comparisons were based on cash flows before taxes and royalties.

Results from several fields, summarized below, indicate that properly applied UB operations yield clear economic benefit. Logical explanations exist for fields where UB operations did not yield favorable results.

After choosing a good UB reservoir candidate, it is essential to predict well productivity prior to drilling for the purpose of comparative economics. Weatherford has developed a screening tool that requires a minimum of readily available data (drilling data and reservoir properties) to predict skin damage. Knowing skin damage, production forecasts can be generated for both conventional and UB operations for comparative evaluations. Built into this tool are real results from numerous reservoirs worldwide. It has been used to screen key formations in several U.S. basins.

Randall Cade, U. S. Chief Reservoir Engineer for Weatherford's SURE group, notes that: "Contrary to conventional wisdom, UB operations can result in significant skin damage if executed poorly; unplanned overbalanced pulses can create serious production impairment. Because many UB-drilled wells are completed openhole or with a slotted liner, UB drilling can be thought of as a concurrent completion process requiring detailed planning. Companies willing to do the UB planning, especially in semi-depleted environments, can be highly rewarded for their efforts."

Field data/results excerpted from "Horizontal UBO Can Outperform Conventional Wells," Drilling Contractor, July/August 2005, pp. 42-45 available online at www.iadc.org/dcpi/dc-julaug05/July05-horizontal.pdf. Based on SPE Paper 91593 (www.spe.org) presented at 2004 SPE/IADC Underbalanced Technology Conference.

For information for screening and production forecasting for UB drilling, contact Weatherford's Randall Cade, randall.cade@weatherford.com.