Some Controlling Factors Regarding Variable Weighting of Cement Slurries
- M.A. Mallinger (Stanolind Oil and Gas Co.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- December 1950
- Document Type
- Journal Paper
- 10 - 11
- 1950. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 1.11.2 Drilling Fluid Selection and Formulation (Chemistry, Properties), 1.14.3 Cement Formulation (Chemistry, Properties), 1.14 Casing and Cementing, 1.14.4 Cement and Bond Evaluation, 2 Well Completion, 1.11 Drilling Fluids and Materials
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A series of laboratory tests was conducted to determine the limits ofpracticability in regulating the weights of various cement slurries. It wasfound that slurry weights of 12 to 19 lb per gallon could be obtained by addingbentonite to decrease the weight and barytes ore to increase the weight. It wasalso found that barytes ore was not usable in all cements.
Lightweight Cement Slurries Introduction
During the drilling and completion of oil wells the magnitude of the hydraulicpressures exerted on certain formations is critical. In many cases considerablecare must be exercised to prevent drilling mud weights from becoming too high,and in those wells where loss of circulation is a problem, the use of normalweight cement slurries will generally result in lost returns during casingcementing operations. While mud weights can easily be controlled, it isnecessary to exercise care in the selection of weight reducing additives forcement slurries in order that slurry weights may be reduced sufficiently toprevent the loss of a large portion of the cement to the thief formationswithout seriously affecting the setting properties of the cement.
An extensive search revealed that a large number of materials that might havebeen otherwise practicable as a weight reducing additive were not acceptablefor use with oil wet cements because the imposition of pressure on the slurriescaused the additive being tested to be compressed or to absorb water from theslurries, resulting in negligible decrease in the slurry weight.
This search for lightweight additives disclosed that bentonite, a material verycommonly used for reducing the weight of drilling muds and cement, produced thebest results without undue harmful effects on the properties of oil wellcements.
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