The issue of global warming is widespread nowadays with an increase in the surface temperature of the earth. Carbon dioxide, CO2 emission from industrial energy is one of the contributing factors to this issue. The concept of CO2 storage is one of the potential solutions to achieve zero CO2 emissions from the oil and gas industry. In order to have an effective cost solution, existing wells are suggested as CO2 injection wells. Therefore, the structures of the existing wells are assessed to observe the sustainability of the well towards CO2 injection since the wells previously drilled without considering their potential secondary life.
Well screening is carried out through 19 development wells in the RSK field. The method used in this screening including; information gathering through the master database, selection of screening criteria and risk quantification. The screening criteria consist of cement quality and quantity, casing metallurgy and wellhead grade. The screening results will be categorized under three different risks; low, high and unknown-risk. Each of the categories and the evaluation methods will be discussed in-depth in this paper.
The assessment resulted in 44% of low-risk well, 50% of the high-risk well and the remaining 6% of the unknown-risk well. The high-risk well is when the well does not meet one or more screening criteria set out, while the low-risk well clearly shows the well fit all the standard as CO2 compliance well. The unknown-risk is classified when there is no sufficient information to do the evaluation. It can be observed that most of the high-risk wells are from the first drilling campaign, while the latest campaign contributes to most of the low-risk well. To reduce the severity of high-risk well, squeeze cementing, geopolymer cement, wellhead modification and workover can be suggested. At the same time, detailed report searching from operators and service companies can be recommended to unknown-risk well.
The study is a quick look well screening for CO2 storage well. In order to strengthen the screening result; reservoir continuity, caprock integrity and comprehensive well assessment concentrating on packer integrity, tubing integrity, injection pressure, internal and external pressure and corrosiveness of injection fluid can be carried out to transform the high-risk well into a low-risk well and classifying the unknown-risk into a specific class.