Controlled Use of Downhole Calcium Carbonate Scaling for Sand Control: Laboratory and Field Results on Gullfaks
| Autor: | Niall Fleming, Terje Østvold, Eivind Berge, Leif Olav Josang, Mohamed Ridene, Hans Christian Rohde |
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| Rok vydání: | 2012 |
| Předmět: | |
| Zdroj: | SPE Production & Operations. 27:223-232 |
| ISSN: | 1930-1863 1930-1855 |
| DOI: | 10.2118/144047-pa |
| Popis: | Summary Gullfaks has been in production since 1986 and produces approximately 11 500 std m3/d of oil from three Condeep platforms. The average water cut is approximately 75 to 80% and gas/oil ratio (GOR) is approximately 200 std m3/std m3. It has been estimated that between 50 and 100 t of sand is produced yearly per platform, with approximately 60 to 70% of the wells in active production (approximately 90) limited by sand production. The typical well completion is cased hole with selective production through perforated liners. Rock-mechanics studies have shown that sand will be produced irrespective of well inclination and perforation design. On Gullfaks, the sand-management strategy used has been to produce wells at "maximum" or "acceptable" sand rates. This strategy has led to significant gains in production, although there are challenges with this approach that include choke erosion, sand removal from the separators, and oil-in-water quality associated with discharge to sea. In response to this, Statoil has investigated different methods of retaining sand downhole by chemical sand consolidation, of which in-situ calcium carbonate (CaCO3) precipitation will form the basis for this paper. This technology involves squeezing into the near-wellbore formation predefined concentrations of urea and calcium nitrate along with the enzyme urease. After application, the well is shut in, during which the enzyme catalyzes the decomposition of urea to bicarbonate that reacts with calcium to form calcium carbonate. This paper will provide details of the laboratory evaluation and, in particular, will focus on the field results from the first-ever application of this type. A low-risk candidate well was selected that had a short perforated interval (19 m) and produced 88 std m3/d oil with a water cut of 94%. Results of the operation design and planning, logistics examination, thorough risk evaluation, and post-operation results with lessons learned will be presented. |
| Databáze: | OpenAIRE |
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