A Look at Processes Impacting Foamed Cements

Abstract This paper presents the results of a joint industry study with the American Petroleum Institute (API) and the National Energy Technology Laboratory (NETL) to assess three sets of field-generated foamed cement at in-situ conditions using surface operations. In this data set, industrial bottled N2 gas was used to generate the field samples versus the cryogenic nitrogen in previous tests. The advantage in using bottled N2 was the ability to mix and pump at lower rates while maintaining an accurate nitrogen delivery, thus allowing collection of low quality foamed cement samples. Foam quality is a measure of the ratio of gas to slurry. Additionally a static capture manifold or split manifold was used for the foam capture which allowed for foam isolation while maintaining the defined rates and pressures. This also gave the ability to maintain the capture pressure during transfer of the samples to the pressurized containers. A foam accumulator chamber was added to the static capture manifold and was charged with foam and subsequently displaced with N2 while filling the sample cylinder. This paper presents results of X-ray Computed Tomography scans of the constant pressure sample cylinders which showed that collection processes have a dramatic influence on the structure of the cured foamed cement. Physical properties such as porosity and permeability, were also measured and indicate a strong relationship between foam quality and homogeneity of the samples. This research will ultimately offer the ability to predict the behavior of foamed cements under in situ conditions when compared to laboratory generated foamed cements.