Oil-based Cuttings Treatment Based On CO 2 Switching Solvent

With the national energy demand continues to increase, unconventional oil and gas reservoirs begin to explore commercial development. Because of the particularity of reservoirs geology, oil-based drilling fluid is usually used for exploitation, generating large quantity of oil-based drill cuttings(DC). Due to DC s special properties and the environmental protection laws and regulations all over the world, traditional technologies are puzzling limited in cost or security aspects. CO2 switchable solvents are green and mildly reacting solvents which can effectively be applicable to extract and separate mineral oil from DC for the solvent's properties will be changed between high and low polarity when CO2 introduced to and exhausted from the system. Therefore, in this paper, CO2 switchable solvent is used in the treatment and mechanism analysis of DC for contriving a novel, low energy consumption and high safety processing method.First of all, physicochemical properties obtained by component analysis are combined with literature research and MSDS(Material Safety Data Sheet) query, CyNMe2(N,N-Dimethylcyclohexylamine) with lower price and better water-resistance ability is picked out for DC treatment. Compared with petroleum ether and toluene, CyNMe2 also performs a desirable extraction effect, and SEM(Scanning Election Microscopy) is used for verifying a equivalent result between CyNMe2 and toluene.Secondly, oil extraction is designed and analyzed by RSM(Response Surface Methodology), and the influencing factors are sequenced with Ratio, Time, Temperature and Speed. Extraction model is built to acquire the best reaction conditions:Ratio=1.4, Time=22.4min, Temperature=47.2?, Speed=150.0r/min, resulting in oil residual of 11642.1 mg/kg and extraction rate of 92%.In addition, When CO2 induced the solvent to transform for hydrophilic and recover mineral oil, the influencing factors of contact area and CO2 concentration will impact on the subsequent protonated reaction. Results show that enlarging flux and temperature are benefit to shorten the reacting time, with conductivity as index. Solvent can be fully protonated with 2L/min bubbling and room temperature in 10 minutes.Finally, UV(ultraviolet spectrophotometry) is chosen to contrast various solvent recovery rate. It's proved that the rate and the effect of water treatment would be balanced when soluble alkaline and precipitable alkaline make-up is added in the water phase. FT-IR(Fourier Transform Infrared Spectoscopy) analysis indicates the structure characteristics of solvent is not changed before and after recycling. Solvent recovery rate can be improved to 91% when water phase takes part in the reuse, where a DC treatment device design is confirmed based on CO2 switchable solvent.