Abstract
The oil production in Zistersdorf, Austria operated by the Rohölaufsuchungs AG (RAG) has a long history beginning with the first completion in 1937, and a variety of production technologies were applied. The reservoirs here are primarily of Sarmatian sand stones showing good compaction and permeability in lower zones but highly unconsolidated sands and serious sand production in upper formations.
The sands in these upper layers are poorly sorted, so it is difficult to realize sand control. In the past, sand production has been handled by metal wire wrap screens combined with gravel packing. Large amounts of finer particles, however, made it necessary to downsize the slot openings in order to protect pumps and jewelry. In consequence, the wells experienced an increase in pressure drop over the screens and the gravel packing, in some cases resulting into production losses of up to 50%.
With the newly developed stand-alone ceramic sand screens, this disadvantage could be eliminated, and sand control in the unconsolidated formations was successfully proven in the Gaiselberg 16 well.
This paper will present the design of the applied ceramic screen, its deployment underneath the downhole pump and the production data of Gaiselberg 16. The evaluation of productions rates, pressure drops and sand measurements will be discussed and compared with performed sand retention testing. The paper will give an interpretation of the sand retention mechanisms of the ceramic sand screen and its capability to assist the building up of a natural formed gravel pack.
