Design Of Completion String For Gas Field A In The South China Sea

The completion string has direct contact with the fluid from the formation and performs the function of oil and gas transportation from the formation to the ground during the whole production period.Whether the oil and gas can be produced safely and efficiently depends on whether the completion string configuration is reasonable or not.A Gas field in the South China Sea is an offshore deep-water gas field,with features such as high production rate,long production life,complex completion string configurations,and high rationality and stability requirement for the completion string structure.Given the above characteristics of the A gas field,a study on the optimization of the completion string for the gas field has been carried out and the following conclusions can be drawn from the analysis:(1)A literature review on the completion string configuration has been carried out the optimum configuration has been proposed.(2)The materials of A gas field were selected by using the material selection chart combined with inlab corrosion experiments,and the suitable material for each well has been determined as: 13 Cr.(3)Completion string dimensions have been determined after the productivity analysis,friction loss analysis,liquid carrying capacity analysis and solid-free erosion analysis.3.5 inch:A3?A4?A5?A9?A10?A11 wells;4.5 inch:A1?A6?A7?A8 wells;5.5 inch:A2 well.(4)Completion string strength analysis has been performed with the consideration of the piston effect,the spiral bending effect,the bulging effect,and the temperature effect.The safety factor method was used to calculate the string strength before and after corrosion under different working conditions,the steel grade and the pound per foot for the completion string were determined.3.5 inch-L80-10.2 lb/ft completion string:A3?A4?A5?A9?A10?A11 wells;4.5 inch-L80-13.5 lb/ft completion string:A1?A6?A7?A8 wells;5.5 inch-L80-20 lb/ft completion string:A2 well.(5)Numerical simulation and Salama model were used to study the solid phase particle erosion in the pipe column.The calculation results show that there is no erosion risk of the completion string under the current selection scheme,which further verifies the rationality of the selected completion string scheme.