Add time:08/20/2019         Source:sciencedirect.com

To keep the stability and integrity of wellbore, it is required to figure out the interaction between clays, water and rock strength in the drilling process. As revealed in available literatures, a high content of clays usually leads to a low value of rock strength and can easily result in the deformation of rocks. However, few studies can succeed in taking the mineral composition and the cement type of clays into consideration. By combining scanning electron microscope (SEM), X-ray diffraction (XRD) analysis with the Brazilian tests, this research can explain the overall effects of clays on the rock strength and deformability behaviors in three kinds of sandstones. The results indicate that the content contrast cannot be a determinant factor in specifying the rock strength. When compared with a lower value, a higher clay content can also exhibit high tensile strength due to a difference in the cement and mineral composition characteristics of clays. Moreover, chlorites were found to contribute more to the strength loss when encountered with water than montmorillonite and illite. This is most likely due to its undulatory surface which can trap much water and thus locally cause massive expansion of clays. According to the cement types, the fracture patterns can be classified into three groups: (1) Grain sliding occurs when abundant clays cement the matrix. The fracture goes through the soft clay cement and the contact surface between clays and grains. (2) Grain fracturing occurs when the clays cannot prohibit the quartz overgrowth, and the fracture can run across the silica-cemented grains. (3) Grain shearing occurs when the rock matrix is unconsolidated and is filled with few clays between grains. The fracture tends to break the rock grains apart in an irregular behavior. Meanwhile, the strengthening mechanism of lost circulation materials was also studied by tracking their migrations through porous media using energy-dispersive system (EDS).

We also recommend Trading Suppliers and Manufacturers of Chlorite-group minerals (cas 1318-59-8). Pls Click Website Link as below: cas 1318-59-8 suppliers