Since 1989, Husky Oil has drilled twelve horizontal wells in six maturevertical hydrocarbon miscible floods. To date, these horizontal wells have beenvery successful in reducing gas coning in the horizontal well and in improvingoil productive as originally intended. However; actual field performanceindicates that in some cases horizontal wells also considerably improveproductivities of adjacent vertical wells.
This paper presents a case history which shows that drilling a horizontalwell in Rainbow Keg River E Pool resulted in benefiting the offset verticalwells with a 10–15% increase in oil production and a temporary cessation in therising trend of producing gas-oil ratio. Such unexpected benefits are believedto be improved drainage to the vertical wells induced by the drilling of thehorizontal well along with healing and/or reduction of gas coning tendency nearthe vertical wellbores. These hypothesized causes for the unexpected benefitswere qualitatively confirmed with a 3-D simulation.
It is concluded that drilling of horizontal wells could improve adjacentvertical wells' productivities. The key implication for future fieldapplications towards further enhancing oil recovery is that under mostsituations the fear of drawing gas from a vertical well to a horizontal well ifthe horizontal well is placed too close to existing vertical well(s) can besomewhat reduced. After placing a horizontal lateral in a target area, the wellcan be extended to cover areas near offset vertical well(s) to improve drainageand reduce some of the gas coning tendency around the offset verticalwellbore(s).
Since 1989, Husky Oil has drilled twelve horizontal wells in six maturevertical hydrocarbon miscible floods (Figure 1). The original intent of thehorizontal drilling technology in these reservoirs are two fold:
to minimize coning and channeling of gas and water, and,
to attain larger drainage area, resulting in incremental oil sandwichrecovery and improving the oil productivity.
To date, all of these horizontal wells have been extremely successful inreducing gas coning and in improving oil productivity. On average, initial capital investment is paid out within oneyear. The length of the lateral sections has increased from 178 m in the firstwell to as long as 720 m and each well was drilled into a progressively riskiertargets.