The need for environmentally acceptable cement additives hasrnencouraged the development of new additives based onrnbiopolymers, especially in the North Sea area wherernenvironmental regulations are very strict. The main challengernis to develop environmentally acceptable chemicals that meetrnthe relevant environmental legislation and operationalrncriteria, and thus could replace synthetic materials that arerncurrently being used. This paper will describe the developmentrnof a cement fluid loss additive that meets the challengesrndescribed above.rnCellulose-type materials have been used for decades asrnadditives to control cement fluid loss. These are PLONORrn(pose little or no risk) listed materials, which means they dornnot have to be subjected to testing protocols. They werernagreed upon by all OSPARCOM (Oslo-Paris Commission)rncountries, and thus, required no further extensive ecotoxicityrntesting before introduction. However, cellulose-type materialsrnthat have been used so far have several limitations: their fluidrnloss control properties decrease at temperatures above 200°F,rntheir salt tolerance is limited and over-retardation problemsrncan occur at low temperature. Furthermore, the slurry viscosityrnto fluid loss ratio is unfavorable compared to that of currentlyrnavailable synthetic fluid loss additives. When these celluloserntype materials are combined with other additives to helprnimprove their performance, the environmental advantages arerncompromised, and the resulting substance can no longer bernlisted as PLONOR.rnThis paper describes the development of a modifiedrncellulose (HEC) type of cement fluid loss product. It is saltrntolerant, it can perform well up to temperatures as high asrn280oF and is environmentally acceptable. After extensivernlaboratory testing, the production has been scaled up forrnintroduction and a successful field trial has been performed inrnthe North Sea area.
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