The Boscan Field, Maracaibo, Venezuela is using a unique approach to sand control. The completions use a combination of premium sand control screens and artificial lift that are designed to have a controlled level of sand production.
The Boscan formation is considered unconsolidated due to the lack of cementing agents, and the nature of the mineralogy. Lab studies have shown that low drawdowns will initiate sand production, and field experience shows that the drawdown caused by the artificial lift techniques used does induce sand production. Several other factors such as the crude which has a 10 API gravity and a viscosity that ranges from 300 to 2000 cps also affect the completions in the Boscan Field. In addition, the productive intervals range from 300 to 600 ft in length with large shale breaks between zones in many cases.
There have been several types of sand control implemented in the Boscan Field. The major methods of sand control prior to 1996 were stand-alone and gravel packed slotted liners. Since 1996 the completions have included open hole and cased hole completions using a variety of sand retention methods that include 12 & 16 gauge all weld and pre-packed screen, stand alone low profile screens, and premium all metal screens.
This paper discusses a lab study that evaluated several types of sand control screens for stand-alone and gravel packed completions using a technique developed by ChevronTexaco Exploration & Production Technology Company (EPTC) (8). The mineralogical characteristics of the formation that contribute to the sanding potential of the field are described. The rational for using a sand control technique that allows a certain amount of sand production is discussed in detail. In addition, production data including sand production for several types of completions are compared.