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Sulfide-Scale-Formation and -Inhibition Tests for a Gas-Condensate Field

Fig. 3—Dynamic vessel for CaCO3-/sulfide-deposition tests.

This paper describes various sulfide inhibitor-testing techniques that have been applied to candidate products for the management of zinc sulfide (ZnS) and lead sulfide (PbS) in a gas/condensate field with a known relatively severe ZnS/PbS scaling problem. The paper presents sulfide static- and dynamic-test measurements along with thermal-aging results that show some encouraging results in terms of ZnS/PbS inhibition.

Glenelg Field

The Glenelg field is a gas/condensate field discovered in 1999 by exploration; production began in 2006. Glenelg is located in the southern part of the central graben of the North Sea, and it is part of an area where there have been a number of gas/condensate discoveries within Jurassic and Triassic (Fulmar) sandstone formations. For a geological description of the field, please see the complete paper. The Glenelg reservoir has three producing layers (A, B, and C), with the top of the reservoir at approximately 5815-m true vertical depth with diverse reservoir characteristics: thickness ranging from approximately 50 to 150 m, porosity of between 13 and 17%, permeability between 0.3 and 60 md, and water saturations in the range of approximately 28–89%.

Scaling-risk studies for Glenelg show that the primary scaling risk is from calcium carbonate (CaCO3) both in the well and in the production facilities, with halite in the production facilities attributable to the high salinity, as is the case with other high-pressure/high-temperature gas/condensate wells nearby. However, pressure/volume/temperature studies showed hydrogen sulfide (H2S) content at approximately 30 ppm, with anticipated levels of H2S at approximately 55 ppm during production, although approximately 5 ppm was measured from core barrels. The petrographic reservoir-characterization and -connectivity study shows evidence of pyrite, sphalerite, bitumen, and iron minerals in the reservoir. The presence of H2S is indicated to be as a result of thermochemical sulfate reduction.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 169798, “Sulfide-Scale-Formation and -Inhibition Tests for a Gas/Condensate Field With Severe Scaling Conditions,” by Cyril Okocha and Kenneth S. Sorbie, Heriot-Watt University; Christian Hurtevent and Salima Baraka-Lokmane, Total; and Marcus Rossiter, Total E&P, prepared for the 2014 SPE International Oilfield Scale Conference and Exhibition, Aberdeen, 14–15 May. The paper has not been peer reviewed.
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Sulfide-Scale-Formation and -Inhibition Tests for a Gas-Condensate Field

01 September 2014

Volume: 66 | Issue: 9

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