The lack of planning for well plug and abandonment (P&A) during the well-construction phase can significantly contribute to the extended operational time and associated high cost of P&A. The impact on time and cost is mainly due to insufficient well data, uncertain casing cement integrity, and lack of information on competent formation for permanent barrier placement. Undocumented pressure and stress evolution, and well events also can contribute to increased time and cost of P&A.
Although new technologies can reduce plug and abandonment cost, another approach is to effectively plan for well abandonment during the front end engineering design (FEED) and well-construction phases and during drilling of new wells.
This paper examines recommendations for improvement and requirements that should be addressed by the industry, regulators, and operators to introduce clear well-abandonment requirements into FEED and well-construction phases for new drilled wells.
Requirement for planning for well integrity for the entire well life cycle of the well from well construction to well abandonment and after well abandonment
Identify number and position of required barriers for abandonments
Requirement to identify and document competent formation during well-construction phase
Requirement to demonstrate there is cement with good bond / isolation between the casing and the formation in the areas where internal cement plugs are to be set.
Qualification of the formation as possible well barrier
Well monitoring: consider introducing sensors or instrument in cement (cement behind casing) to continuously monitor and track any pressure build-up in the casing annulus.
Completion design: Avoid control lines at the intended well-barrier depth(s) and install production packer(s) in a location enables through-tubing well-abandonment methodologies.
Other considerations to be addressed in this paper are the change of regulations between the time the well is constructed, and its final P&A.
The novelty of addressing well abandonment requirements in the FEED and well-construction phases will significantly simplify the abandonment phase reducing risks and cost while improving well barrier integrity.