Modified-starch applications as fluid-loss reducers in water-based drilling fluids: A review of recent advances

A type of natural resource found in nature, starch and its derivatives, homologues, and other compounds have a wide range of sources. These materials are cheap to obtain and have the advantages of low toxicity, rapid breakdown, and limited environmental footprint. However, starch's actual commercial usage remains relatively constrained, largely due to its low stability as its temperature increases, poor solubility in water, and a propensity to ferment at certain temperatures. However, certain modified forms of starch do display high-temperature tolerance that increases their attractiveness for a wider range of applications. In particular, modified-starch products are becoming more widely used in drilling fluids (DF) and certain enhanced oil recovery (EOR) techniques. Modified starch displays good biodegradability, but some bonds in the starch molecule can lead to radiation degradation under certain conditions. This results in reduced polymerization, base fracture, and even carbonization, limiting its range of application. This review characterizes different categories of modified starch, describing the history of their industrial application. In the oil and gas industry DF applications predominate to date, encouraging research efforts to seek improvements in the temperature-resistance of modified starch. The review considers the processes and economic and environmental issues involved in DF applications of modified starch.