Deep Well Killing Process Simulation And System Design

With the continuous extension of the oil and gas resources exploration and development, complexity of drilling and risk of well control are growing as well as technical requirements of drilling are increasing. In order to meet the higher requirements of exploration and development, the drilling security must come first. The technology of well pressure control is a key step for safe drilling, and well killing technology is the core of well pressure control technology. At present, conventional well killing for deep wells and ultra deep wells usually use the driller’s method and engineer’s method. However, these killing processes are relatively fixed and lack the strain capacity in the complex situation on the field. When variable density method taken into consideration for well killing, the defects of driller’s method and engineer’s method can be well solved. However, the kill curve of variable density method is more complex and the killing process control is more difficult. Therefore, it needs to establish a mathematical calculation model which can calculate real-time SPP and CSP during the conventional killing process. Then according to the computational model, a monitoring system was designed which can use computers to monitor and control the killing process.Considering the researches on characteristics of deep wells and ultra deep wells, well killing methods and killing processes at home and abroad, the paper establishes a mathematical calculation model which can calculate real-time SPP, CSP and pressure of casing shoe during the conventional well killing process. The principle of the model is based on the position of well bore structure and drilling string to divide flow channels, then based on density and volume of slurry injected to segment slurry and calculate hydrostatic pressure and circulating friction of each segment; Then determine theoretical standpipe pressure, casing pressure and casing shoe pressure on that moment. The mathematical calculation model not only analyzes the calculation of SPP and CSP during variable density well killing, but also makes the calculation of SPP and CSP more accurate than what obtained by the driller’s method and the engineering’s method.Considering the field vibration, electromagnetic interference and other mal-conditions during well killing, and combining the characteristics that deep well, ultra deep well may contain sour gas and have high temperature and high pressure down hole, and after investigating the performance and price of instruments and throttle and Industrial PC of dozens companies at home and abroad. Industrial PC are chosen from the pressure sensor, flow sensor, density sensor, hydraulic throttle valve for site well killing operation, and the data acquisition device which can be installed a portable computer. Under the premise that closely combining with the process at site, the overall structure of the monitoring and control system of the well killing are designed.Based on the established mathematical calculation model, computer data acquisition technology and Windows operating platform, a killing process simulation and automatic control system software wrote by Delphi7,that integrated data input, data management, parameter calculation, process simulation, real-time data acquisition control and kill the process. Through giving an exploratory No.1well in northeastern, the reliability and stability of the software is verified. The results show that the established mathematical calculation model which can calculate real-time SPP, CSP and pressure of casing shoe. The Kill monitoring system not only can solve the complex calculation of kill parameters and low degree of automation during killing process that used variable density method, but also improve the success rate and killing security, which reduces the labor intensity and operational risk of the on-site personnel.