How Fluid Loss Influences Primary Cementing: Literature Review and Methodology
- Gerard Daccord (Schlumberger Dowell) | J.F. Baret (Schlumberger Dowell)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling & Completion
- Publication Date
- June 1994
- Document Type
- Journal Paper
- 133 - 138
- 1994. Society of Petroleum Engineers
- 1.14 Casing and Cementing, 1.8 Formation Damage, 2 Well Completion, 3 Production and Well Operations, 4.1.3 Dehydration, 2.2.3 Fluid Loss Control, 4.3.1 Hydrates, 1.14.3 Cement Formulation (Chemistry, Properties), 2.2.2 Perforating, 1.11 Drilling Fluids and Materials, 1.6 Drilling Operations
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Fluid loss during cementing has long been suspected to have detrimental consequences, including reduction of slurry volume; increased slurry density and viscosity; cement-cake deposition, which may cause additional decreases in friction pressure during placement; and near-wellbore reservoir filtrate invasion. This paper briefly reviews and quantifies these consequences. Given well geometry, job design, and cement slurry fluid-loss properties, we show how to predict the critical phenomena that are most likely to impair cementing and the most sensitive well or slurry parameters. By coupling these results and the degree of accuracy with which well parameters are known, one can calculate prediction uncertainty (the error bar) and deduce the key parameters that affect this error bar.
The effect of fluid loss on well cementing is well documented. Many phenomena have been suspected to play a role in this effect, but no critical comparison exists concerning their relative importance because fluid-loss agents for cements are expensive and many operators believe that the mudcake provides sufficient fluid-loss control. The first objective of this paper is to review the literature to discern the importance of fluid loss in primary cementing and to establish ways of comparing various means by which fluid loss may affect primary cementing. This review will provide tools that can be used to predict whether good fluid-loss control is needed for a specific cement slurry on a given job. Most of the time, prediction of requirements for wellbore fluids is restricted by limited knowledge of downhole behavior. Cement slurry filtration often has been said to be limited by the mudcake, but until recently no field measurements supported this position. Thus, any prediction should account for the inaccuracy of input data. We will indicate one way to account for such inaccuracies.
This paper will deal exclusively with primary cementing and will not consider other practical situations, such as squeeze or lost circulation. In the next section, we briefly review quantification of filtration properties. Then, we describe published consequences of fluid loss and their quantification. Finally, we consider the effect of input data uncertainty on predicted fluid-loss control requirements.
Filtration Regimes and Characterization
Two limiting filtration regimes correspond to static (or pseudostatic) filtration and dynamic filtration. A crossover regime exists,4, but we shall not consider it. Generally, the surface cement cake controls behavior, and the effects of an inner cake (formation damage) are ignored. Consequently, the filtration pressure is the difference between slurry and formation pressures.
|File Size||317 KB||Number of Pages||6|