Experimental study on the oil-based drilling cuttings treatment technology based on supercritical CO₂ extraction method

In order to improve the harmless oil-based drilling cuttings treatment technology and increase resource recoverability, this paper studied the oil-based drilling cuttings treatment technology based on supercritical CO₂ extraction method. After its basic principle and technological process were introduced, a test device was constructed to carry out laboratory experimental study on this technology. In the experiments, the base oil in the drilling cuttings was extracted successfully and the minimum oil content of the dry drilling cuttings after extraction was as low as 0.13%, indicating that this technology is technically feasible. And the extracted base oil has no peculiar smell with low solid content, which satisfies the requirements of secondary drilling fluid preparation. Then, based on the experimental results, the influences on the extraction effect by pressure, temperature, time, water content of drilling cuttings, entrainer and other factors were analyzed. Finally, the key parameters for the industrial application of the oil-based drilling cuttings treatment technology based on supercritical CO₂ extraction method were recommended as follows: extraction pressure 10 MPa, extraction temperature 35 ℃, extraction time 1 h, minimum CO₂ circulating pressure of extraction system 4.5−5.7 MPa, cooling temperature 1−5 ℃ and no entrainer. The research results provide technical support for field application.