Field Decommissioning - Chapter 1 PDF

1.3 An oil and gas project cycle Source: Canadian Audit & Accountability Foundation n.d. Dr. Huyen Le Field Decommissioning 13  1.4 Challenges at the end of an oil & gas project cycle ❖ Output declines → Revenue will no longer su...

1.3 An oil and gas project cycle Source: Canadian Audit & Accountability Foundation n.d. Dr. Huyen Le Field Decommissioning 13  1.4 Challenges at the end of an oil & gas project cycle ❖ Output declines → Revenue will no longer surpass operating & maintenance costs ❖ Improvement of subsea tieback & extended reach technology → increase recoverable reserves & extend the production life BUT - Unplanned delays → additional expenditure (maintenance costs, insurance, bond premiums & fees to be paid until removal of installation) Source: Ferreira & Suslick 2000, p. 3 Dr. Huyen Le Field Decommissioning 14  1.6 Phases in the decommissioning process All activities managed by operator to support decommissioning process via planning & implementation A well isolated from the reservoir permanently Activities required to prepare the installation & associated infrastructure for total or partial removal Removal preparation, general management of removal vessel operations, offshore fastening of components, transportation & off-loading to an onshore yard… - Removal & management of subsea infrastructure - Returning the site to a state similar to that before development Near shore operations, breaking down of the asset once onshore & subsequent management of all waste streams Source: ARUP 2014, p. 19; Foreign & Commonwealth Office 2017, pp. 17-19 Dr. Huyen Le Field Decommissioning 25  2.1 Causes of well abandonment ❖ Temporary abandonment - Profitable but not having use options - Within production plans but being idle - Temporarily ceased to be repaired or prepared for use ❖ Permanent abandonment ❖ Non-profitable (well ending) ❖ Profitable but unsafe Source: POC1 2019; PVEP 2019a; Vrålstad et al. 2019, p. 478; Bộ Công thương 2020 Dr. Huyen Le Field Decommissioning 5  2.1 Causes of well abandonment ❖ Low oil prices → commercial viability & potential life extensions Decommissioning market → service contract prices Eg: Oil price on 19 September 2024 Text source: Offshore 2020 Figure source: Oilprice.com n.d. Dr. Huyen Le Field Decommissioning 6  2.1 Purposes of well abandonment → To emplace plugs consisting of cement plugs supported by mechanical plugs Text source: Walsh & Heagle 2016, p. 1 Image source: NORSOK Standard D-010, p. 105 Figure 1.1.2 Dr. Huyen Le Field Decommissioning 11  2.1 Environmental aims ❖ Of all P&A operations: Isolate & protect all fresh & near freshwater zones Figure 1.1.3 Figure 1.1.4 Text source: Abshire et al. 2012, p. 43 Figure source: Taha & Amani 2019, p. 4 Dr. Huyen Le Field Decommissioning 12  2.1 Environmental aims ❖ Of all P&A operations: Isolate & protect all future commercial zones Figure 1.1.5 Text source: Abshire et al. 2012, p. 43 Figure source: Diaz 2017 Dr. Huyen Le Field Decommissioning 13  2.1 Environmental aims ❖ Of all P&A operations: Prevent leaks in perpetuity from or into the well Figure 1.1.6: Potential leak paths Figure source: Vrålstad et al. 2019 Text source: Abshire et al. 2012, p. 43 Dr. Huyen Le Field Decommissioning 14  2.1 Financial aims ❖ P&A operations: time-consuming & costly - Offshore well abandonment costlier than onshore well abandonment - P&A costs: make up the majority of decommissioning costs (40%-60% of total decommissioning costs) E.g: ✓ North Sea: Up to £3 billion/year for decommissioning in the upcoming years, 50% of which on P&A ✓ UK: P&A costs over the next 30-40 years: $24 billion → Cost-efficiency → New cost-effective technologies, methods and solutions Source: Kaiser 2015, p. 200; Moeinikia et al. 2015, p. 2; Davison et al. 2017, p. 1; Smith & Tunget 2017, p. 4; Fam et al. 2018, p. 259; Vrålstad et al. 2019, p. 478 Dr. Huyen Le Field Decommissioning 16  2.2 TA definition ❖ Norway’s standards (NORSOK Standard D-010) Temporary abandonment – with monitoring - Well abandoned with primary and secondary well barriers continuously monitored & routinely tested - No maximum abandonment period Temporary abandonment – without monitoring - Well abandoned with primary and secondary well barriers NOT continuously monitored & NOT routinely tested - Maximum abandonment period to be 3 years Source: Standards Norway 2013, p. 84 Dr. Huyen Le Field Decommissioning 9  2.2 TA definition ❖ Vietnam’s legislation (Decision No. 10-VBHN-BCT & Circular 17/2020/TT-BCT ) TA seen as “bảo quản giếng” – use suitable fluids & install plugs & equipment inside the well to ensure safety in a defined period, after which the well can be explored, tested & produced conveniently - Well type 1: Wells need to be plugged for a long period (>3 years), including wells proved to be profitable but not having use options - Well type 2: Wells need to be temporarily plugged (1-3 years), including wells within production plans but being idle - Well type 3: Wells need to be shortly maintained (= External pressure → Burst loading → Surface pipe rupture → Surface pipe communication with the aquifer ❖ E.g.: Decision 10/VBHN-BCT (Art. 25) - Testing pressure of cement plugs > Pressure that tests the receivability of the formation at the outer casing shoe 500 psi - If the former much higher than the latter → Surface pipe rupture Figure 2.2.3 Text source: King & Valencia 2014, p. 10; Jerez 2015, pp. 37, 38 Figure source: DrillingFormulas.com 2014; Jerez 2015, p. 38 Dr. Huyen Le Field Decommissioning 11  2.5 Semisubmersible drilling rig ❖ Most expensive in UK waters (about US$5 to 6 million per well) ❖ One of the most expensive offshore activities (~ 3 million NOK per day for the rig alone) → rarely used for P&A ❖ Only viable option for P&A on the Norwegian Continental Shelf at water depths beyond the reach of jackup rigs ❖ Moves more slowly than a light well intervention vessel (LWIV) & must be used immediately at contract time Figure 2.3.2 Text source: Abshire et al. 2012, p. 44; Handal 2014, pp. 38, 39; Moeinikia et al. 2014, p. 2 Photo source: Rigzone n.d.b Dr. Huyen Le Field Decommissioning 8  2.5 Light well intervention vessel (LWIV) ❖ Advantages compared to rigs: - Significant cost savings (day rate for vessel: app. 30%-40% of rig cost) (cost falls between abandonment using a jackup rig & a semisubmersible rig) - Significant time savings (moving quickly and easily bw work site locations, operating with dynamic positioning) - Reduced operational times (30-60 hours) - Safer & more efficient lifting operations for well stubs, well heads & structures Source: Noble 2013; Agullar etal. 2016, p. 3 Dr. Huyen Le Field Decommissioning 10  2.5 Light well intervention vessel (LWIV) ❖ Used for Phase 0 (preparatory work) and complete Phase 3 (wellhead and conductor removal) in P&A ❖ P&A operations: - Kill the well - Punch the tubing - Set the deep-set and shallow temporary plugs - Remove the X-mas tree Source: Moeinikia et al. 2014, p. 2; Moeinikia et al. 2015, p. 5 Dr. Huyen Le Field Decommissioning 11  2.5 Wireline ❖ Run or pull tools or measurement devices into and out of the well to perform well interventions ❖ A continuous, small diameter cable with the attached equipment run in or out of the hole through an electro-hydraulic or diesel-powered winch ❖ Two cable systems: - Slickline: mechanical operations - Braided line (with or without an electric cable): tractor applications Figure 2.3.6 Text source: Henriksen 2013, pp. 110, 111 Figure source: Smith & Tunget 2017, p. 28 Dr. Huyen Le Field Decommissioning 13  2.5 Coiled tubing ❖ Like single strand wire (slickline) with the exception of a larger diameter and an internal passage for pumping fluids ❖ Operating mechanism: a flexible steel pipe (without connections) is run into and out of the well to perform different operations ❖ Used for cleaning out the well prior to a plug placement and for setting primary, secondary & surface barriers Figure 2.3.7 Text source: Henriksen 2013, p. 113 Figure source: Smith & Tunget 2017, p. 28 Dr. Huyen Le Field Decommissioning 14  2.6 Procedure and application ❖ Mill a window through all casing strings (cement pumped into the annuli and against the exposed formation) ❖ Remove any cement, settled mud or other debris from between the casing and the formation ❖ Used in many P&A operations globally Figure 2.4.3 Figure 2.4.4: Milled windows Source: Vrålstad et al. 2019, p. 485 Source: Abshire et al. 2012, p. 49 Text source: Abshire et al. 2012, p. 49; Vrålstad et al. 2019, p. 485 Dr. Huyen Le Field Decommissioning 8  2.6 Disadvantages of section milling Highly viscous drilling fluid Swarf Figure 2.4.5 Figure 2.4.6 Equivalent Circulating Densities > Easy damage of surface equipment the formation’s fracture gradient Losses while circulating, swabbing, well control, poor hole cleaning, and packing off of the Bottom Hole Assembly (BHA) Text source: Ferg et al. 2011, p. 1; Abshire et al. 2012, p. 49; Vrålstad et al. 2019, p. 485 Plug cementing: Photo source: Baker Huges n.d.; - Time-consuming → costly EPFL n.d. - Difficult to perform safely and effectively Dr. Huyen Le Field Decommissioning 9  2.6 PWC advantages - Remove old mud, swarf and settled mud weighting material from the annulus space through perforations → Eliminate the use of a high Equivalent Circulating Densities fluid to remove swarf → Reduce the potential of Bottom Hole Assembly’s “pack offs” - No need to section mill or cut-and-pull the casing → time efficient & cost-effective Source: Ferg et al. 2011, p. 2; Vrålstad et al. 2019, p. 485 Dr. Huyen Le Field Decommissioning 15  2.6 When to use which techniques? ❖ Quality of cement plugs set by SM better than by PWC ❖ PWC: more time-saving & thus cheaper AND executed more easily → Chosen instead of SM Figure 2.4.10: Barrier by Section Milling Figure 2.4.11: Barrier by PWC Source: Weatherford 2016 Source: Archer 2017 Dr. Huyen Le Field Decommissioning 18  2.6 Procedure and application ❖ Applied for some wells in the North Sea in 2013 ❖ Not commonly used in global P&A, especially for production wells ❖ Applied by PVEP team for SK305 project, offshore Malaysia, saving about US$5 million ❖ Nature of caprock: Create a non-permeable formation (caprock) above the production formation to prevent fluids from migrating to the surface Figure 2.4.12: Simplified illustration of a typical plug (PPGUA 3.0) and a caprock (OGUK & NORSOK) Source: PVEP 2019 Text source: PVEP 2019 Dr. Huyen Le Field Decommissioning 20  2.6 Advantages of caprock ❖ No retrieval of the whole production tubing to the surface → Limit risks → Save time/costs for P&A of production wells Figure 2.4.13: A P&A schematic using caprock Source: Yusof et al. 2018 Text source: PVEP 2019 Dr. Huyen Le Field Decommissioning 21  2.6 Advantages of caprock ❖ Suitable for wells with many packers & monobore wells ❖ For wells with poor annulus cement: much more cost-effective than Section Milling Figure 2.4.14: A typical offshore production well before and after P&A Text source: PVEP 2019 Source: Vrålstad et al. 2019, pp. 479, 480 Dr. Huyen Le Field Decommissioning 22