Analysis of Fluid-Loss Data

Summary Over the last few years, fluid-loss testing has evolved from static to dynamic testing. Data analysis, however, has not progressed as rapidly as the experimental techniques used to gather the data. In this paper, various techniques of analyzing dynamic fluid-loss data are discussed and a simple, yet effective, method of describing dynamic fluid-loss curves is presented. The analysis of dynamic fluid-loss data is usually based on the traditional square-root-of-time treatment. This type of analysis works well for static fluid-loss test data because the dynamic processes are less complex than those in dynamic situations. During a dynamic fluid-loss test, a number of different events influence the fluid loss and the shape of the fluid-loss curve. Not only filter-cake compression, but also dynamic cake deposition and cake erosion must be taken into account. In most cases, Darcy flow does not occur over the whole time span of the test. Several complex methods of treating the data from dynamic fluid-loss tests have been suggested, but most rely on modifications of the static fluid-loss-data analysis technique. These techniques are based on the data as a function of the square root of time. With dynamic fluid-loss test data, the square-root-of-time relationship does not adequately describe the fluid-loss data. A straightforward technique to analyze dynamic fluid-loss data is discussed in this paper.