Environmental Biodegradation and Drilling Performance of Water-based Polyampholyte Drilling Fluid

摘要

Some of drilling fluids are a mixture of many components including organic as well as inorganic polymers. In order to assure stable parameters and the required technological parameters of drilling fluids, all components must be resistant to downhole conditions. At the same time it would be beneficial if the drilling fluids were biodegradable after the drilling process. As such they would have less of an environmental impact and would be easier to utilize. Organic polymer-based drilling fluids are efficient and environmentally-acceptable, but sensitive to biodegradation so they are treated with biocides. The treatment adds toxicity and makes the waste fluid difficult to dispose off [1]. The challenge in polymer fluid fomulation is to reduce biodegradation of active (while drilling) fluid and increase biodegradation of the waste fliud. Presented in this paper is a study of drilling properties and environmental performance of fluid based on newly synthesized ampholyte polymer. Drilling performance of the new fluid was evaluated with regard to rheology, filtration, salt and temperature resistance. Samples of the fluid were tested using API Standard Methods. Environmental study addressed the fluid biodegradation. Biodegradability was investigated using Merck method. The Merck method uses testers with agar surfaces. The bacterial count/ml of the sample is determined by comparing the density of the colonies appearing on the slide with densities shown on the model chart. The results were compared to results for fluids with starch agents. The results show that polyampholytic-starch fluid is biodegradable by bacteria but still has good and stable rheological parameters and filtration. The findings show the advantages of polyampholytes and drilling fluid with polyampholyte components and provide some perspectives for industrial implementation.