Long-Term High-Temperature Laboratory Cement Data Aid in the Selection of Optimized Cements

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractCements placed in gas wells for Saudi Arabia drilling operations were evaluated for physical properties. Three intermediate casing cement compositions were tested. The cement systems tested were: 1) bentonite extended, 2) standard density class G and 3) optimized particle packing lightweight system containing hollow ceramic spheres. These tests were requested because of concerns that the cements that were currently being used were not durable in the long term. Khuff and pre-Khuff gas wells in Saudi Arabia have high production rate potential therefore the curing test temperature of 300 o F and test pressures of 3000 psi were applied to the samples. The samples were cured for one year.The tests performed were API compressive strength tests, permeability, shrinkage or expansion, Young's Modulus, Poisson ratio, rheology and settling. Data for 24 hour, 7 days, 1, 2, 3, 6, 9 and 12 months test periods are presented for all cements.Certain cements, for which there are no previously published shrinkage data, have been identified. New technology in cement laboratory testing identified undesirable properties in certain cements. Using this new lab technology, some cements exhibited undesirable short and long-term physical properties. Data representing various cement slurry designs and corresponding physical properties results are included in this paper.

An innovative test apparatus for oil well cement: In-situ measurement of chemical shrinkage and tensile strength

“…The magnitude of shrinkage at 20°C and atmospheric pressure was reported to be about 2.2 mL/100 g cement after 48 h. Early studies of oil well cement shrinkage under pressure either used sealed specimens [20] or involved equipment with pistons pushing directly against cement pastes [21,22]. These results did not represent the total chemical shrinkage as the internal voids in the specimens formed during hydration were not accounted for.…”