A Study of Low Temperature Cementing
- W.M. Thorvaldson (Dowell of Canada)
- Document ID
- Petroleum Society of Canada
- Journal of Canadian Petroleum Technology
- Publication Date
- June 1962
- Document Type
- Journal Paper
- 64 - 71
- 1962. Petroleum Society of Canada
- 2 Well Completion, 1.11 Drilling Fluids and Materials, 4.1.2 Separation and Treating, 1.13.3 Cement Formulation (Chemistry, Properties), 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 1.13 Casing and Cementing, 5.2.1 Phase Behavior and PVT Measurements, 4.3.1 Hydrates
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Since 1957 Dowell of Canada has been conducting a survey, in the field andin the laboratory, of temperatures and cementing strengths encountered drillingin Western Canada. In an attempt to rectify the seemingly inadequate cementstrengths, several different corrective measures have been developed, testedand evaluated. This paper is designed to acquaint the industry with theinvestigation from the initial surveys to the successful cementing of a stringof casing wholly in perma frost.
Well temperatures exert a profound effect on the setting properties ofcement slurries. Consequently, cements must be carefully formulated so thatadequate thickening times are obtained for a proper placement of the slurry,yet WOC times are not unduly prolonged. In the Canadian oil fields, especiallyduring the winter months, low temperatures present a formidable problem,especially in setting surface casing, where the formation temperature is belowthe freezing point of water. Oddly enough, very few data are available onformation temperatures in the depth range of surface casing, or the effectsthat these temperatures have upon cementing practices.
The range of surface temperatures encountered is shown in Figure 1, whichshows the mean temperatures characteristic of this area. Assuming a liberaltemperature gradient of 2°F. per 100 feet and an average surface pipe depth of600 feet, it may be seen that the B.H.T. varies from approximately 50°F. in thesouth to 17°F. in the north. These temperatures, although modified by thepenetration of drilling fluids, are dangerously close to and often below theminimum temperature necessary for the setting of commonly used cements.
As an example of the formation temperatures usually encountered Figure 2shows the temperature profiles of two wells surveyed under static conditions.One of these wells was located at Resolute Bay, N.W.T., the other in northernAlaska. Both of these wells are in the continuous Perma-frost zone, indicatingfrom 1000 to 1500 feet of Perma-frost.
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