Application-Appropriate Drilling Technologies Excel in Managed-Cost Mature-Asset Environments

摘要

Production in most wells follows a predictable pattern dictated byrnthe decline curve. Initially high production is quickly followed by arnlong, measured decline. This potentially long decline in production,rntogether with an ever-increasing demand for energy, has resulted inrnmany mature, low production fields. To stem the decline inrnproduction in these wells and extend the viable economic life ofrnthese assets, operators are increasingly turning to advances inrntechnology. Technologies such as improved slimhole re-entryrndrilling bottomhole assemblies (BHAs), enhanced reservoirrnnavigation systems, and improved conventional drilling techniquesrnare successfully meeting the challenges of developing mature fieldsrnin established oil and gas basins around the world. Thisrncombination of techniques and technologies is being used in thernWilliston Basin to increase the recoverable reserves and improvernthe present economic value of each asset.rnProduction from the Williston Basin declined from the time of itsrninitial discovery through the early 1990s. The introduction ofrnhorizontal re-entry drilling technologies then revitalized this region.rnTargeting these thin beds typically requires extending 4?-in.rnLaterals from existing or new vertical 7-in. cased wells. In the recentrnpast, re-entry performance was confined by well placementrnrestrictions, water and salt zones, and available drillingrntechnologies. These requirements restricted the wellpath tornrelatively tight radius build sections. Together with the drillingrndifficulties associated with slimhole tubulars, these tight buildsrnoften resulted in high drag in the hole, limiting the lateral section torn3,000 to 4,000 ft due to weight transfer and drag constraints.rnHowever, in recent applications that did not suffer from suchrnrestrictions or the consequences of the water/salt formation holerninstability issues, larger radius curves could be incorporated into thernwellplan. This increased radius reduced drag in the well program,rnwhich together with improved motor technologies and experiencedwellsite execution, allowed the 4?-in. re-entry section to achievernworld record open slimhole multilaterals. The successfulrncompletion of such multilateral wells provide for over 10,000 ft ofrnpotential reservoir exposure in this thin bed.