Search citation statements
Paper Sections
Citation Types
Year Published
Publication Types
Relationship
Authors
Journals
The current oil and gas industry uncertainty encourages innovative, efficient, and simple drilling and workover solutions. Challenging and problematic formations cause various design complications and operational risk. These include lost circulation, well control incidents, high density drilling fluid systems, tool design limitations, etc. Such troubles can also lead to liner and casing leaks downhole and eventually undesired surface pressure buildups across the tubing-casing and casing-casing annuli. The case study well was drilled and completed, but prior to production a tubing-casing annular pressure of 6,500 psi was recorded. With two liners in the well casing designs (4-1/2 in. and 7 in.), a well leak was suspected to be at the top of the 7 in. liner as it was laying across a deep and over-pressurized formation with a 152.5 pcf gradient. After commencing the workover operations and due to downhole leaks and washouts, the well had to be killed off-bottom with 160 pcf manganese tetroxide (Mn3O4) mud. The well was fully decompleted, except for the production packer, which was left in hole. Investigation and diagnostic operations showed leaking 7 in. liner body and liner top packer. To repair the leaking 7 in. liner, the team introduced an innovative design with a 4-1/2 in. x 7 in. tapered scab liner to sting into the newly installed repair packer and extend above the existing 7 in. top of liner to set on the 9-5/8 in. casing, and so cover the leaks. A mechanical 7 in. x 9-5/8 in. hanger and liner top packer system was deployed to allow for cementing the scab liner then setting these mechanical tools, where hydraulically actuated systems were impractical. Due to the high kill mud density of 160 pcf, a special 165 pcf Mn3O4 -Hematite cement recipe was adapted. Despite the high slurry density, this formulation allowed for optimal mixing, pumping, and leak isolation operations. This paper will highlight the case study well history and challenges leading to liner leaks while emphasizing the nature of the over-pressurized formation. It will demonstrate the mechanical tapered scab liner design and deployment procedures in comparison to the conventional scab and tie-back liner jobs.
The current oil and gas industry uncertainty encourages innovative, efficient, and simple drilling and workover solutions. Challenging and problematic formations cause various design complications and operational risk. These include lost circulation, well control incidents, high density drilling fluid systems, tool design limitations, etc. Such troubles can also lead to liner and casing leaks downhole and eventually undesired surface pressure buildups across the tubing-casing and casing-casing annuli. The case study well was drilled and completed, but prior to production a tubing-casing annular pressure of 6,500 psi was recorded. With two liners in the well casing designs (4-1/2 in. and 7 in.), a well leak was suspected to be at the top of the 7 in. liner as it was laying across a deep and over-pressurized formation with a 152.5 pcf gradient. After commencing the workover operations and due to downhole leaks and washouts, the well had to be killed off-bottom with 160 pcf manganese tetroxide (Mn3O4) mud. The well was fully decompleted, except for the production packer, which was left in hole. Investigation and diagnostic operations showed leaking 7 in. liner body and liner top packer. To repair the leaking 7 in. liner, the team introduced an innovative design with a 4-1/2 in. x 7 in. tapered scab liner to sting into the newly installed repair packer and extend above the existing 7 in. top of liner to set on the 9-5/8 in. casing, and so cover the leaks. A mechanical 7 in. x 9-5/8 in. hanger and liner top packer system was deployed to allow for cementing the scab liner then setting these mechanical tools, where hydraulically actuated systems were impractical. Due to the high kill mud density of 160 pcf, a special 165 pcf Mn3O4 -Hematite cement recipe was adapted. Despite the high slurry density, this formulation allowed for optimal mixing, pumping, and leak isolation operations. This paper will highlight the case study well history and challenges leading to liner leaks while emphasizing the nature of the over-pressurized formation. It will demonstrate the mechanical tapered scab liner design and deployment procedures in comparison to the conventional scab and tie-back liner jobs.
Downhole casing repair is a major workover operation worldwide, especially in wells which were drilled and put on production decades ago. The presence of corrosive formations is considered a common downhole source that slowly corrodes steel strings over time. Several remedial options are available on the commercial shelf including cement slurry, resin chemicals, and mechanical casing patch technologies. Yet, these suffer from several disadvantages including limited isolation and integrity, cost, internal diameter restriction, etc. These drawbacks could lead to casing leaks reoccurring across the same depth shortly after applying the commercial treatments. In other scenarios, they result in internal diameter reduction and inability to pass tools, such as plugs, packers, whipstocks, etc. The proposed epoxy resin formulation retains improved mechanical and chemical properties over the commercial products to repair challenging downhole casing leaks, especially those with low injectivity. This formulation is composed of a combination of two different resins and one curing agent. Compared to other commercial epoxy and polyester products, this formulation showed lower rheology of less 50% at room temperature, deeper crack penetration, improved compressive strength and elasticity, and enhanced corrosion resistance. The product was deployed in the field to cure downhole 7 in. casing leaks with 73 pcf CaCl2 brine in place. The subject leak showed low injectivity of 0.4 bpm at 1,000 psi, requiring solid-free solutions. The innovative formulation was introduced as a result, and 20 bbl were spotted as a balanced plug and squeezed in hesitation to achieve the required pressure integrity of 600 psi after resin plug cleanout. Manganese Tetroxide was used as the weighing agent to mix up 80 pcf epoxy resin as per design. The low-rheology allowed for maximum injected volume at the required lock-up pressure of 1,000 psi. Meanwhile, the elastic nature enabled more resistance during the following re-entry operations and relatively higher rates of penetration during resin plug cleanout. This paper will discuss the nature of the resin formulation and experimental work to compare this innovative product to the commercial products. The pilot testing, job simulation, and field deployment will be highlighted to emphasize the added value and potential of this product.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.