Increasing sand production is a common problem in maturing fields, resulting from declining reservoir pressure and increasing amounts of water. Sand production has an impact on both production and safety, because sand causes erosion of production equipment. In some cases, increasing sand production triggers premature shut down of production wells.
Statoil has more than 400 sand producing wells in the North Sea. The sand producing reservoirs with the lowest formation strength are located in the Gullfaks field. (The reservoir rock disintegrates when it is squeezed between the fingers). As a result, Gullfaks was the first field to systematically enhance sand management through investments in knowledge and technology.
Cooperation between Statoil and DNV was established, and a systematic review of the erosion phenomena was conducted. The major break-through of the sand management project reached surface in 2001, which made it possible for Statoil to control the oil production according to an Acceptable Sand Rate (ASR) instead of a Maximum Sand free Rate (MSR). As a direct consequence, the oil production from the Gullfaks field has increased.
The Insight - Erosion Management System software (ABB) was installed on the Gullfaks field, and is today keeping track of the actual wall thickness reduction due to the sand production in chokes and other erosion nodes. Besides from an increased production and improved safety situation, the software provides an economical gain due to condition based inspection and maintenance operation. Based on the experiences from the Gullfaks field, the system is now also in operation on the Statfjord field, which has seem similar results (SPE 94511)