Graeme Fyfe, DTI, explains how new technology can answer multiple thru-tubing plugging challenges in a single solution.
The upstream oil and gas industry faces combined thru-tubing challenges of high integrity sealing, inflow HPHT deployment, high-differential pressures and ultra-high outer diameter (OD) delta transformations.
A new additive manufactured technology provides a reliable solution, particularly in water shut-off/cement retainer applications or where other solutions may have failed.
M-Bubble technology was launched in 2023 after four years of development and has notched up several notable achievements in the field. By 1Q25, fifteen commercial deployments have successfully solved a variety of operator challenges in onshore, offshore and subsea wells, including an unparalleled 291% OD transformation, with zero failures and no NPT. Industry uptake is accelerating rapidly with significant levels of repeat business in DTI’s project pipeline.
Pioneering additive manufacturing in downhole technology
Additive manufacturing (AM) is widely used in the aerospace industry, where precision and reliability is paramount, as well as in the automotive and medical sectors. Over several years, DTI has taken these learnings and applied them to its inhouse engineering processes for the manufacture of downhole tools and component parts.
Direct metal printing is an additive manufacturing process that builds complex metal parts from 3D data. The process uses a high precision laser directed onto metal powder in vacuum conditions to selectively build thin horizontal layers one after the other, adding metal only where it’s required and removing the need for redundant material created by subtractive machining. Metal printing using exotic materials such as Inconel is relatively new, but by avoiding expensive waste the process enables the rapid manufacture of high-quality precision components at a much lower cost. The process also enables designs that would otherwise not be possible and it has the capacity to turn traditional multiple part assemblies into single pieces. The time and cost savings achieved through direct metal printing are significant.
Inconels are a class of nickel-chrome based super alloys characterised by high corrosion, oxidation and creep resistance. They can withstand high temperatures and extremely corrosive environments; however, they are prone to work hardening during conventional machining, which can damage cutting tools and deform the product.
To support DTI’s AM processes the company employs finite element analysis (FEA) during the design process and computerised tomography (CT) scanning during manufacture to inspect its 3D-printed parts. This ensures a high level of precision, both dimensionally and in the porosity of the material, helping to highlight any potential issues in the print data. CT scanning is the most advanced x-ray inspection technique available and is an ideal non-destructive, non-contact method of obtaining internal and external information on the printed part down to a micron level of certainty.
In-house testing of DTI’s M-Bubble element demonstrated an extremely high level of repeatability not found in parts manufactured using conventional machining. DTI’s AM units are designed and manufactured in line with established AM industry codes and guidelines that have been in circulation in the aerospace industry for several years, as well as emerging oil and gas specific AM codes such as DNVGL-ST-B203.
A folded metal bubble
In the M-Bubble, Inconel additive manufacturing has enabled a design that was once impossible to achieve. In its run-configuration DTI’s M-Bubble adopts a slimline fluted form with curved folds which retain both thickness and strength. This design, inspired by origami engineering and compact folded space technology, allows the plug to pass through narrow production tubing and well restrictions then transform into a robust metal ‘bubble’ which conforms to the shape of the wellbore at setting depth using an injected hydraulic fluid. The precise design geometry of the folded metal element enables a large transformation ratio between run and set sizes, while maintaining its original intrinsic strength.
The M-Bubble’s metal structure is encased in a robust elastomer for reliable hermetic sealing. The overall device offers much greater strength and resilience than a conventional elastomer expansion solution or inflatable plug and has great utility for inflow operations at higher temperatures and pressures. Low cost, high utility cement retainer options are also available without elastomer.
With its combination of temperature, pressure and diameter deltas, the M-Bubble technology can be used as a bridge plug, packer, packoff, patch, straddle or cement platform to service a wide variety of applications including well completion, recompletion, workover, production optimisation/ zonal isolation and abandonment. There are also valuable applications for this technology in the repurposing of oil and gas wells for the carbon capture and gas storage sector.
The products are available in different sizes up to 7.625 in. outer diameter (OD) and in pressure ratings up to 5000 psi., all qualified to API standards, with higher pressure ratings and sizes up to 9.625 in. currently in development.
Unparalleled performance in the field
The first commercial deployment of DTI’s M-Bubble bridge plug was in 1Q23, for a water shut-off application for a major operating company in Kazakhstan. A compact 2.125 in. OD M-Bubble Plug was successfully deployed on slickline through narrow tubing with a 2.2 in. ID. DTI’s hydromechanical setting assembly (HMSA) activated the M-Bubble slips, then pressurised hydraulic fluid was injected into the metal element causing it to unfold and seal within the 5.5 in. liner (4.95 in. ID) under a differential well pressure rating of 3500 psi. Once this permanent plug was set, the HMSA automatically released and the toolstring was pulled. Six months later, the M-Bubble’s hermetic seal was verified by a production logging run. Following the success of the first deployment, the operator placed further orders with DTI for a multi-well campaign.
Similar water shut-off projects using the M-Bubble plug have been completed in a high temperature North Sea subsea well and offshore Australia in a deep, deviated well. In the latter project, the operator had already tried to set high expansion plugs without success so had approached DTI for a solution. The plug needed to pass through 4.5 in. tubing with a 3.26 in. restriction and a 65° deviation and set and seal in a 7.625 in. liner at a depth of almost 2000 m. This was a non-standard size requirement so DTI designed, manufactured, tested and supplied a new M-Bubble in just twelve weeks. The plug was pressure tested a few weeks later, successfully verifying its integrity.
For zonal isolation applications the M-Bubble enables the operator to isolate pressured and flowing zones in a fast and cost-effective single run without the use of cement, which would typically be a three-run operation. This solution is highly desirable, especially in cases where cement cannot be deployed due to the well configuration, where dynamic fluids prevent reliable depositing or when circumstances make dumping cement unacceptable. This also saves rig time and ‘wait-on-cement’ time, which can accumulate significant savings for the operator especially in deeper, extended reach wells.
However, where the operation does require a cement plug, the M-Bubble can be used in its cement platform configuration without the inclusion of a high-pressure seal. This is a practical, cost-effective and high utility solution for cement plugging and was commercially deployed for the first time in June 2024, in the North Sea. In this project the M-Bubble Cement Platform, with just a 2.125 in. outer diameter, achieved an impressive 291% transformation to set in a 7 in. liner.
Meeting industry need
M-Bubble technology has been developed by DTI to answer the industry’s need for through-tubing isolation solutions in wells with narrow restrictions, high deviations, large deltas in tubing diameters and deeper, hotter (177° C) and higher pressure (6500 psi) environments.
Another key advantage of the technology is the high differential pressure rating achievable after setting, even without slips being used, in comparison to conventional expansion products. These alternatives, although they may have similar expansion ratios, would need additional cement laid on top to provide a barrier capable of withstanding a differential pressure of over 3000 psi. This leads to additional runs in hole to add cement and wait-on-cement time for the curing process to ensure a competent barrier is in place, adding extra rig time and cost to the operation. Additionally, when the barrier needs to be positioned in a highly deviated section of the well, effective cement placement can be difficult. The use of the M-Bubble bridge plug benefits the customer by saving on rig time and cost in any well, but particularly in high deviation wells.
To enable greater industry uptake, DTI has designed the M-Bubble so it can easily be deployed using industry-standard equipment by a wide range of operators and service companies on a global scale. The activation force for setting the M-Bubble has been tailored to the output from standard mechanical or pyrotechnic setting tools that are commonly run on slickline, electric line or coiled tubing, thus avoiding the additional cost, availability and shipping of a proprietary setting tool.
The combination of highly desirable technical and operational capabilities, demonstrated by this advanced thru-tubing plugging technology, provides operators with a compelling solution for many applications in onshore, offshore and subsea wells worldwide.
Image: the M-Bubble element in its set-in-hole bubble form (left) and run-in-hole fluted form (right).
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