Method for predicting scaling trend of CO2 gas flooding oil-gas well shaft

Abstract

The invention provides a method for predicting the scaling trend of a CO2 gas flooding oil-gas well shaft. The method comprises the following steps of by collecting water sample analysis data, according to the well shaft temperature and pressure conditions and the known ion concentration, calculating the CO3<2-> concentration and the HCO3<-> concentration with the scaling trend under the well shaft conditions through a trial iteration method by depending on the Davis-Stiff saturation index theory, drawing a CO3<2-> and HCO3<-> concentration curve when calcium carbonate scale is generated underthe well shaft temperature and pressure conditions, detecting the CO3<2-> and HCO3<-> concentration in water produced at a wellhead, and taking corresponding scale removal and prevention measures when a predicted value is reached. The limitation that an existing scaling prediction method cannot predict the scaling trend of the CO2 gas flooding oil-gas well shaft is achieved, the method is appliedto prevention and treatment of the calcium carbonate scale in a non-scaled well shaft, the scaling trend of the CO2 gas flooding oil-gas well shaft can be accurately predicted, and then a reasonablescale removing and preventing scheme is formulated.

Description

technical field [0001] The invention relates to the technical field of oil and gas field development, in particular to a method for predicting CO 2 A method for wellbore scaling trends in gas flooding oil and gas wells. Background technique [0002] In the process of oilfield exploitation, especially in the period of high water-cut oil production, some oil wells will be fouled. Scaling in oil wells will block pipelines and cause production decline, which has become one of the important factors that plague oilfield production. Calcium carbonate scale is a common scale in most blocks. The mechanism of calcium carbonate scaling has been studied in depth at home and abroad. The scaling mechanism is Ca in water. 2+ with CO 3 2- CaCO 3 precipitation. [0003] Calcium Carbonate (CaCO 3 ) scale is a very common scale in oilfield production. Generally, its solubility increases with increasing salinity in water; increasing temperature and decreasing pressure will reduce its so...

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Problems solved by technology

[0005] However many take CO 2 Oil and gas wells with gas flooding do not have wellbore scaling at the beginning, and subsequent CO 2 During the gas drive development process, due to changes in mining methods and work systems, fouling of wellbore and surface equipment affects production from time to time, and the existing technology does not predict CO 2 Method for scaling trend of wellbore in gas flooding oil and gas wells

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