EXPERIENCE WITH THE USE OF TETRAKISHYDROXYMETHYLPHOSPHONIUM SULFATE (THPS) FOR 'IRE CONTROL OF DOWNHOLE HYDROGEN SULFIDE

摘要

TetrakisHydroxyMethylPhosphonium Sulfate (THPS) is used as a bactericide in the Skjold/Gorm oil productionsystems in the Danish sector of the North Sea. A reduction in H_2S generation downhole due to THPS treatment resulted insavings on H_2S scavenger consumption. In addition, use of THPS provides other benefits which are discussed in the paper.THPS treatments are compared with conventional bactericidal treatments and it is demonstrated how downholeinjection of THPS retards the growth rate of Sulfate Reducing Bacteria (SRB) and the rate of H_2S production. THPStreatment resulted in a change in the downhole bacterial population, evidenced by changes in the sulfur isotope ratio of theproduced H_2S.Re-injection of produced water with low H_2S concentrations increases the potential for iron sulfide (FeS) deposition,both in topsides and downhole. THPS changes both the physical form and the bacterial content of the FeS deposits. Removalof the deposits with acid is facilitated by TI-IPS which exhibits FeS dissolving capabilities. Field tests have verified the effect.