High Oil Paraffin Wax Deposition Law And Prevention Research

During the development in reservoir with high content of wax, with the drop of temperature and pressure, oil tubing and ground lines are often caused congestion by precipitation and deposition of paraffin oil in the crude oil, and even shut down the oil production. Oil in C Reservoir is in high content of wax, tubing frequent congestion, wax removal in short cycle, high operating costs, these in all that have seriously affected the production running smoothly.In this paper, based on the thorough research of paraffin deposition theory and a large number of experimental studies, the establishment of a wellbore wax dynamic prediction model had already guided field wax removal operation, and acquires the following understanding:(l)Ivestigated the chemical composition and physical character of paraffin deeply,and analysised the mechinasm of paraffin deposition, surmmaried the harm of wellbore paraffin deposition,we recognized that paraffin deposition is a complex chemical-physical process and result of the function of a variety of mechinasm.(2)Analysised the major factor that affected the process of paraffin deposition,and surmerized the general methods to inhibit paraffin deposition and evalued the features of a variety of methods to inhibit paraffin deposition.The results indicates that chemical paraffin remover and inhibitor is easy to operate and functions long time,the effect is obviously,and the cost can be reduced obviously.(3) Analysis to the D well oil sample about density, viscosity, viscosity-temperature curve, IR, paraffin carbon number distribution and structure of the carbon chain shows that the viscosity and density of the oil sample are both high at room temperature, high content of heavy fractions, containing about12.7%of wax, along with asphalt, resin and mechanical impurities. The paraffin in this well is the coarse crystal wax which is consist of about83%paraffin mainly by the C16～C30alkanes and a small amount of heterogeneous hydrocarbon composition;(4) Test the D well oil sample about wax precipitation point and content under different pressure and temperature. The results show that, D well of crude oil in the wax point under atmospheric pressure is about27.3℃and is about48℃under the bottom hole pressure; under a given pressure, the wax content increased with temperature decreasion, while in the same temperature, the wax content increased with pressure increased. Under temperature and pressure of the wellhead,50to60%of wax content of crude oil will be deposited in the wellbore;(5) A new type of paraffin remover and inhibitor DK-5was obtained by orthogonal experiment. The optimal concentration ratio of the X:pour point depressant Y:the dispersant Z is1:0.6:1. Evaluation of the DK-5showed that the effect was significantly better than other agents with the same concentration. When the dosage of the agent was0.5%, the wax inhibiting rates of oil well with wax can be about80%. The melting wax speed was4.12mg/(mL.min) and increasing with the temperature. The melting wax speed will also increase with the reducing of the moisture content in wax;(6) Because of wax deposition is a static and dynamic process that deposit after generating, and established a new dynamic forecasting model of wax. So that the static equilibrium model of wax deposition and the current prediction model has been unified, the solution results match with field data well, and proved the reliability of the model;(7) Opening a static prediction of the D well, the wax deposition point at the depth of about600m, and agree well with field data, proved the reliability of experimental results;(8) According to the model of well bore paraffin deposition dynamic forecasting, established the forecast charts, predicted the depth and period of paraffin inhibit and removal of D well. The period is about15days and the depth about720m.