Novel Technique to Determine Cement Contamination

Abstract

Abstract In a well integrity, repair for well AB, 9 5/8″ casing perforated to fix gas breakthrough problem behind 13 3/8″ casing, right after the casings perforation, contaminated cement circulated to surface from the annulus between 9 5/8″ and 13 3/8″ casing. Oil extracted from contaminated cement sample using two solvents, hexane and dichloromethane. The extracts analyzed using gas chromatography. Hexane and dichloromethane extracts, showed that the cement has hydrocarbons in the carbon number region from C8 to C30. Hard cementitious material milled and circulated out of hole from 900 meter downward to S formation at 1440 meter. Having contaminated cement in the top part of the cement column and hard cementitious material downward to the oil reservoir at 1440 meter, then outstanding cement downward to the section TD at 2530 meter, indicates that cement above this reservoir did not hydrate at all. Cement contaminated as a result of the losses encountered right after displacing the cement, the entire cement column form S formation upward to the top of cement contaminated with S formation oil, contaminated cement settled and compacted because of the hydrostatic head above it. Compacted solids prevent further influx to take place. This case history along with the detailed demonstration including the novel lab work will present in this paper.