Study on Economic and Efficient Completion Design of Tight Gas Reservoir

Abstract

Tight gas reservoirs in Daqing Oilfield has the characteristics of deep burial, high temperature and high pressure, and the produced natural gas generally contains CO2. At present, the production casing and tubing of the tight gas reservoir are completed with 13Cr110 material, which has high cost, but the gas production is low, and it declines very fast, so the economic benefit is poor. In order to reduce cost and increase the efficiency, it is necessary to explore a new well completion method in tight gas reservoir. We study the corrosion law of different materials through laboratory experiments, and finally determine that the production casing adopts the assembly method, material of production tubing next to the production packer is 13Cr, other parts are ordinary carbon steel. The tubing and downhole tools are made of carbon steel, and the casing and tubing annulus are injected with annulus protection fluid for corrosion protection. With the comprehensive analysis, this completion method can meet the requirements of gas well corrosion prevention and production. After 20 years of development, the well construction cost of a single well has been reduced by 79% to 7.553 million RMB. The effective implementation of this design can provide reference for the subsequent development of tight gas reservoir in Daqing Oilfield.