We will be showcasing the practical approaches / considerations in designing a CO2 injection well covering the engineering aspects, cost optimization and sustainable design for the injection period. This will also include the software aided simulations for the practical load analysis for selection design parameters and materials for the CO2 injector in an optimized manner. We will also address the importance and relevance of the MMV (monitoring, measurement, and verification) method to the CCS project and its influence on the well engineering scope. To deliver a sustainable well design, we referenced the existing CCS project against those undertaken in other parts of the world and identified the challenges, best practices, and operational approaches undertaken in those other wells. The well design and engineering has taken into consideration the existing internal and industry standards as well as lessons learnt from other CCS campaigns. The evaluation for the well design and construction was conducted to identify potential gaps lacking in the CO2 injection design in offshore carbonate environment. From the identified injection location, evaluation criteria were finalized to assist in decision making for the overall well design requirement covering injectors and observations wells. The injector well design and construction will be able to successfully counter the subsurface challenges faced in the overpressure clastic formation and depleted carbonate reservoir. The design of the well will also be capable of surviving the external and internal loads due to the injection operation for the duration of the campaign life. Furthermore, the design has taken into consideration the temperature reversal impact on surface and downhole due the supercritical CO2 fluids which has low temperature in nature. We also developed testing procedures and evaluation matrix for the fluid wetted (CO2 injection fluid) sections to optimize material selection for the wetted zone as a major well cost contributor resulting from the CO2 resistance materials. We are converting some of the identified end of field life producer wells into observations wells via sidetracking and workover methods. The current overall well placement between the injectors and observation wells has achieved a comprehensive coverage area for monitoring of the CO2 plume migration across the carbonate field. This is the first big scale campaign covering the offshore depleted carbonate field as a CCS candidate in the world as previous practices were only undertaken in the clastic environment. Success of this campaign opens more opportunities for achieving net zero carbon emission in the oil and gas industry.

In the current climate, cost reduction has been a major enabler for project sanction. With significant drilling activity planned in relatively benign environments offshore Malaysia, there were potential casing design optimisations, and hence cost reduction opportunities, in analyzing the relevant well planning data of such projects, with a view to further optimising the standardised 13-3/8" surface casing specifications that have historically been used in similar areas. Additionally, the feasibility of using 13-3/8" casing as slim conductor on platform development wells was investigated. Well planning data for a variety of projects planned for between 2022 and 2024, which planned to use the same 13-3/8" surface casing specification, were collated and boundary conditions were established for all of the key parameters. This standardised casing string was first assessed for suitability, and areas for potential optimisation were identified. Simplified casing load analyses optimisation were performed on this optimised 13-3/8" casing specification for typical collapse loads as laid out in the company's casing design standards, to assess its suitability. Generalized fatigue life analyses were also performed on the slim 13-3/8" conductor to try to prove viability of the concept. It was shown that collapse design is the controlling factor for the cost reduction initiatives through 13-3/8" casing specification optimization, especially in an environment of severely depleted reservoir (down to 3 ppg) in the reservoir section underneath the surface casing. This is exaggerated with conservative load assumptions that is used in the industry/company standards i.e., running mud weight, 50% to 100% evacuation, extreme low pore pressure assumption as low case prognosis etc. Combination of conservative collapse prohibited the casing specification to be optimized lower. This paper addresses the 13-3/8" casing optimization through fit for purpose collapse design approach. It was shown that the reduction of the casing specification for 13-3/8" surface casing in the majority of the projects studied was justified and acceptable based on the minimum design requirements for collapse loads. Additionally, cost savings of up to approximately 7% were observed for this reduction in 13-3/8" surface casing specification depending on connection qualification and casing manufacturer.

Typically, most of the well abandonment practice is reference to the recognized industry standards i.e. NORSOK, UK Oil & Gas and etc, and this is how the wells abandonment was carried out in the past. These practices however evolved/changed over time with lessons learnt and experiences and turn into a fit for purpose solutions for the Client. The shift in international and local standards and regulations for a robust plug and abandonment approach has placed the need for a better and long lasting permanent P&A methodology. Adhering to the existing industry standards in well abandonment is somehow not practical and not cost effective to be implemented in different part of the well, where there are major differences in local regulations, reservoir conditions, caprock thickness, well design philosophy and etc. The magnitude of abandonment cost increase is not at par with the risk reduction in long term hydrocarbon leakage. A fit for purpose solutions is recommended in closing the gap between cost and risk. Due to the extremely varied well architecture between wells, the approach to permanent abandonment varies depending on casing sizes, presence of packers and no of casings present to the caprock area. On top of that, identifying the highest depth for a placement of cement plug will reduce on the amount of plugs to be placed, saving rig time and operational time. So far, 16 idle wells have since been permanently abandoned with the systematic approach of applying caprock restoration concept and reinstating the poor isolation across caprock areas with cement with the assistance of technology to the likes of perf-wash-cement, and hydro mechanical casing cutter. These wells have successfully been abandoned as per host authority standards. This paper will explore a major local oil company’ approach to decommissioning of wells, in line with local regulations enforced, while ensuring a cost effective approach is applied in line with the available technologies.

Despite the short planning time of 18 months and very limited geological data, TTD-1 HPHT Exploration well in Block SK of East Malaysia, was successfully drilled to its technical limit by adopting some innovative HPHT practices. Various technical challenges were successfully overcame including an abnormally steep pressure ramp (17 psi/ft), high mud weight (18 ppg), high overbalance (3,000 psi), narrow drilling margin (until 0.7 ppg window), wellbore breathing, pore pressure of 14,000 psi and temperatures of 325° F.During drilling, the actual operating window was successfully mapped out in real-time. The lower boundary was defined by pore pressure modeling, MDT logging and dynamic flow checks using MPD. The upper boundary, fracture gradient, was derived from dynamic formation integrity tests & leak-off tests utilizing MPD. Other techniques such as use of smaller tubular, low-flow MWD tools and bridging agent also contributed to the success. Wellbore breathing was well controlled to a minimum level.Various simulations have assisted the HPHT section to be drilled beyond conventional defined limits. Two real-time monitoring centers assisted in improving drilling efficiency and real-time decision making. The well highlighted limitations of acquiring formation pressure in tight formation using FPWD tools, life of MPD seal element and gas invasion in production zone cementation.The authors will present and share the HPHT drilling practices adopted to successfully drill the deepest HPHT well to date for PETRONAS Carigali in Malaysia.