Drilling mud rheology and the API recommended measurements

Drilling fluids are, among other things, expected to transport cuttings and control fluid loss. The rheology of drilling fluids plays an important roll in both of these aspects of drilling fluid performance. A number of years ago the American Petroleum Institute established a set of standards for evaluating the rheology of drilling fluids. While drilling fluid technology has evolved and drilling fluids have become more rheologically complex, the standards have not changed sufficiently to adequately characterize the new generation of drilling fluids.