Title of Project – Finite-Difference, Numerical Flow Simulation Approach to Develop a Probabilistic Model for Risk Based P&A Well Design Background Information – Decommissioning is the final step in the life of a hydrocarbon well, and it tries to re – establish the cap rock’s original integrity while detaching any damaged sub-surface formations with flow potential from an “eternal perspective.” Hundreds of thousands of well plugging and abandonment (P&A) operations are planned to be carried out globally over the following few decades. Decommissioning operations in the North Sea are only expected to entail the plugging and abandonment of 2,624 wells over a 10-year period beginning in 2019 (Oil&Gas UK 2019). This expansion in decommissioning action level and the related significant expenses of lasting P&A tasks require new, fit-for-reason, P&A configuration devices and functional advancements to guarantee safe and savvy decommissioning of hydrocarbon production wells. Because a failed P&A generally necessitates complicated, risky and costly remedial procedures, as well as significant environmental expenses, reputational harm, and financial loss, meticulous planning and execution is always necessary.

To develop a risk-based model for well P&A, a complete understanding and assessment of long-term performance and integrity failures of P&A systems required which study how likely to happen leakage, at what rate, cumulative volume of leakage and also the path of leakage. Lots of research work is going on and also developed some model which concludes leaked methane concentration does not increase significantly over the years but from the total well surveyed by Boothroyd et al. (2016), 40% of the younger decommissioned well developed leakage while production or right after the decommissioning.

Johnson et.al. (2021) recently released two publications describing the first step and a full-scale well-centric modelling technique also were accomplished using finite-difference numerical fluid-flow simulators. The model was developed using barrier material as cement and was capable of capturing transient effects, which had previously been a research gap. But the research work did not include the term corrosion that is one of the main factor that may defect the barrier metal and also steels in well giving a pathway for gas.

Rationale for Project Work – As there is a lot of research going on to replace cement with other materials as a barrier material, such as resin, metal alloys, and so on, a thorough investigation is required before use, as well as a numerical model and simulation to test applicability. The modelling framework can be used to study the influence of restoration operations on particular flow/leakage channels and overall P&A behavior, providing knowledge to assist guide for the selection of the most efficient and cost-effective remedial workover operation among a variety of design possibilities.

Aim and Objectives – The aim of this research is to develop a framework for well P&A design in which barrier material used is resin and also an in-depth study to understand how corrosive fluid left can influence in defecting the barrier material; at the same time corrosion of steel. This will be finite-difference, grid- based, numerical simulation approach which is the most suitable method for long-term well P&A leakage modelling also used by Johnson et al. (2021) for cement barrier material.

The project objectives are as follows:

1. Review of different modelling methods, their advantages, and disadvantages.

2. Gathering of data for model inputs.

3. Investigation on flow properties of defective barrier material and probabilistic analysis to account for the uncertainties in model input.

4. Identifying dominant flow paths, integration of the results of numerical evaluations and software simulation.

5. Detailed framework and integration of the results of numerical evaluations and software simulation.

Methodology – The project work will begin with extensive research on P&A operation. The research will continue to get an understanding of designs available, barrier material and different numerical as well as simulation methods. Data required for model input will be listed out once thorough study done on simulation process. Data hunting is required to get real time data for the accuracy of the model.

Monte Carlo simulation methods to be used to account for the uncertainty in the P&A model input data, in particular the resin defect dimensions. ECLIPSE software to be used for simulation and MATLAB as a visualization tool. Expected Contributions to Theory and Practice – Develop a framework for risk-based well P&A design considering resin as a barrier material. A theoretical understanding on how corrosive fluid left in the sub-surface formation effect the barrier material and steels in well over the time.

References

JOHNSON, C., HAGHIGHAT SEFAT, M., and DAVIES, D., 2021. Developing a Well-Centric Flow Model, the First Step to a Risk-Based Approach to Oil and Gas Well Decommissioning. Journal of Petroleum Science and Engineering, 204.

JOHNSON, C. et.al., 2021. Development of a Probabilistic Framework for Risk-Based Well Decommissioning Design. SPE Journal, pp.1–18.

BOOTHROYD, I.M. et.al., 2016. Fugitive emissions of methane from abandoned, decommissioned oil and gas wells. Science of The Total Environment, 547, pp.461–469.

BEHARIE, C., FRANCIS, S., and ØVESTAD, K. H., 2015. Resin: An Alternative Barrier Solution Material. Paper presented at the SPE Bergen One Day Seminar, Bergen, Norway, 22 April. SPE-173852-MS. https://doi.org/10.2118/173852-MS.

Oil&Gas_UK. 2019. Decommissioning Insight 2019. London, England, UK: Oil and Gas UK.

Project Plan –

Risk Analysis – There may be some difficulties to get real time data for defected barrier material flow properties. Data hunting to be done in NRD, kaggle and similar websites. Ethical issue – Software or access to lab requirement – ECLIPSE, MATLAB, ANSYS FLUENT