The Wilcox Sands project utilizes dual completion in the zone to produce water-free oil at higher rates than conventional completions. The newly developed production method is accomplished by producing water from perforations in water column below the oil-water contact and oil from second perforations at the top of the oil column. Dr. Wojtanowicz invented the dual completion method, also known as Downhole Water Sink method of production, or reverse coning. He and Mark Swisher of Hunt Petroleum Corp. pioneered this technology in field operations. The theory behind the new completion method is relatively simple, Dr. Wojtanowicz said.
Water cones upward due to the pressure drop caused by oil production.
To prevent this coning, an equal pressure drop must be acting downward on the oil-water contact to keep the water from rising. Later, instead of decreasing, which is the case for conventional completions, the oil rate was increased to about 55 BOPD and remained steady at this rate for over two years. But comparisons of initial costs, production rates and net monthly earnings, and lifting costs between the new dual completion method and the last three conventional completions indicate payout as short as, if not shorter than, conventional completion methods, Dr. Wojtanowicz said. The economic performance of this new method was outstanding. There are several alternative possibilities from the successful results of these examples in Louisiana.