The investment estimation of a systematic drilling engineering project is an important step for oilfield enterprises to strengthen investment control and enhance operation management. The quality of investment estimation does not only decide the feasibility and profitability of the development plan，but also has an important instruction influence on the implementation and operation performance of the approved engineering plan. This paper proposed a method for extracting engineering parameters of drilling investment estimation based on the natural language processing algorithm and the Monte Carlo simulation investment prediction model. These two techniques were introduced into the petroleum engineering estimation，and it was demonstrated via modelling and case studies that all selected control factors were significant and thus effective. Based on the above，the investment estimation was carried out. Natural language processing algorithms were required for parameter extraction and processing，with an accuracy of over 90%. Meanwhile，the Monte Carlo simulation investment prediction model was used for calculation to ensure that the error between the extreme investment and the existing economic evaluation results was less than 5%. This developed method has been successfully applied to 29 production capacity building projects in 2024，identifying and warning 8 projects with excessive investment. It improves the accuracy and efficiency of engineering parameter extraction，enhances the percent of pass for the internal rate of return of petroleum drilling engineering investment estimation，and is of great help in improving the digitalization level of the petroleum engineering estimation.

Gas-liquid separation for the produced fluid of CO2 flooding is an important step in the process of carbon capture，utilization and storage（CCUS），and its efficiency directly affects subsequent crude oil dehydration，associated gas processing，produced water treatment，as well as the selection and operation life of related equipment. Based on the basic composition of the produced fluid，the impact of CO2 on the properties of associated gas，oil and produced water is stated，and the main impacting factors and mechanism of oil foaming and associated gas desorption are analyzed. And then，a solution for efficient separation of gas and liquid is put forward，main methods and application effect of gas-liquid separation are reviewed，and the direction and trend for future study on gas-liquid separation are pointed out. The results show that the relationship between the pressure reduction rate and the foaming characteristics of oil is the key scientific problem to determine the pressure and stage number for gas-liquid separation. Establishing a prediction model for the relationship between oil foam volume and defoaming time under the synergistic effect of multiple factors is helpful to determining the separation time. The organic combination of ultrasonic desorption technology and mechanical separation technology is expected to form a new cost-effective and efficient gas-liquid separation technology