Life-cycle deliquification techniques and their application for deep shale gas reservoirs

Abstract

Deep shale gas resources in the Sichuan Basin have great potential, and this is a major area for future shale gas exploration and development. Deep shale gas wells face problems with liquid loading throughout the production cycle. Regarding deliquification techniques, it is necessary to consider the requirements of gas wells over the full life cycle, as well as the main form of artificial lift used at different stages, to achieve economically efficient development. This paper divides the life cycle of a deep shale gas well into two stages: early production and middle/late production. Pressure-control production is conducted in the early stage of production, whereas investigations on critical liquid-carrying models, the flow distribution in the wellbore, and the main form of artificial lift are conducted in the middle and late stages of production. A recommended scheme of deliquification techniques over the full life cycle has been developed to guide the development and enhancement of artificial lift methods in deep shale gas reservoirs. As of March 2022, in the PetroChina Southwest Oil & Gasfield Company managed-pressure production has been implemented in 14 wells in the early stage of deep shale gas production. In eight wells, plunger gas lift has been implemented in the middle and late stages of production. In seven wells, foam lift has been implemented. The abovementioned techniques are effective in increasing and stabilizing production and achieving deliquification in deep shale gas reservoirs.