Digital Energy Journal- Using 3D printed devices to fix ‘total’ lost circulation events

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Using 3D printed devices to fix ‘total’ lost circulation events

Wednesday, May 3, 2023

Drillers can use a variety of devices to stop drilling fluid getting lost for holes up to 6mm. For bigger holes, researchers at Aramco are experimenting with a 3D printed design. It sounds expensive, but the cost of the lost circulation is much higher, so it is worth doing

Lost Circulation is where drilling fluid is lost into the subsurface. It is a well-documented oil and gas wellbore creation problem, stemming back to when oil wells were first drilled. It still represents a big challenge today when drilling an oil well.

Understanding lost circulation

To understand why 3D printed devices may be useful, it is first important to understand what lost circulation is.

Drilling an oil well uses a fluid to act as a safety barrier. The fluid also acts as a drill bit cooling medium and a well bore cleaning medium, to transport the drilling cuttings from the well as it progresses.

The drilling fluid is circulated constantly. The fluid circulation path is down the drill pipe, back to surface up the outside of the drill pipe. The fluid is cleaned and then pumped back down the drill pipe.

Lost circulation is exactly as the term describes in that drilling fluid pumped down the drill pipe no longer arrives back at surface but leaks into the formation through which is being drilled.

Lost Circulation can cause safety issues and can add millions of dollars to the cost of well bore drilling operations annually.

The severity of Lost Circulation is described by the volume of drilling fluid not returning to surface. It can be small, where just a small volume of fluid leaks into the formation, or large where all of the drilling fluid leaks into the formation.

Lost circulation severity is therefore categorized into 4 widely accepted categories: Seepage, Partial, Severe and Total Losses. Total losses are where all the fluid pumped down the drill pipe leaks into the formation being drilled and nothing returns to surface.

The standard method to remedy lost circulation during the drilling of a well bore is the use of Lost Circulation Materials (LCM). The concept of using LCM has been around since the beginning of oil and gas well drilling.

Simplistically LCM is an additive mixed into the drilling fluid which then blocks up the holes or cracks into which the drilling fluid leaks.

The most common types of Lost Circulation Materials are fibrous, flaky or granular materials such as bark, mineral fiber, hair, mica, plastic, wood, cotton husks or date husks.

Most LCM's are good for small to medium amounts of lost fluid (i.e. Seepage, Partial and low severe losses). Generally the maximum size of leak path standard LCM can block and seal is between 4mm to 6mm.

When losses are higher and a leak path is bigger than 4mm to 6mm the LCM is unable to block and seal the leak path. So LCM becomes an ineffective remedy for the lost circulation as the LCM just flows into the formation with the drilling fluid.

Stopping large loss circulation events remains a significant challenge.

3D printed devices for LCM

A new 3D printed concept patented by Aramco has been designed to be used with standard lost circulation material (LCM) solutions that Aramco have successfully tested and proven to plug and seal large 30mm - 40mm cracks and fissures.

The combined use of this new concept with standard LCM can effectively increase the crack plugging and sealing capacity of standard LCM by 6 to 7 times.

The new concept is to designed to reduce the loss leak hole or crack size such that the standard LCM can then plug and seal designed.

Reducing the leak path size is achieved by introducing a 3D printed Lost Circulation Material 'catcher'.

The catcher is introduced into the drilling fluid and flows with the drilling fluid down the drill pipe and into the loss leak path where it would become wedged, Figure 1 A.

Once the catcher is trapped within the leak path fissure, deployed Lost Circulation Material would collect and bridge on the catcher. This creates a formation pressure seal, stopping the drilling fluid leak as shown schematically in Figure 1 B.

The Lost Circulation Material Catcher concept has been called a Lost Circulation Shape (LCS).

The design of the Lost Circulation Shape is three-dimensional, faceted, hollow and perforated. The shape perforations are designed to 'catch' whatever LCM is used. So the the perforation form and size are matched to the optimum LCM plugging capability.

The external shape of the Lost Circulation Shape is a faceted to facilitate the stacking of individual shapes on top of each other.

The Shape is hollow in order to minimize the volume of material used in construction and create a neutral buoyancy effect within a flowing drilling fluid.

To maintain design change flexibility, and allow Lost Circulation Shapes to be manufactured at any location, 3D printing was selected as the most appropriate manufacturing method.

3D printing has become a widely accepted manufacturing process and allows the creation parts not possible to manufacture through traditional manufacturing techniques.

3D printing techniques allow the creation three-dimensional objects with complex geometry features (internal and external) by building successive layers on top of each other, each layer sticks to the preceding layer until a complete form is produced.

Many different materials can be used in this layering process including metal, thermoplastics, ceramics, composites, glass and even edibles and biomedical.

The ability to create complex geometry features (internal and external) in many different materials without the need for expensive molds or dies was one of main considerations for producing the Lost Circulation using 3D printing.

The flexibility of the 3D printing manufacturing process will allow rapid bespoke design modification of the Lost Circulation Shape to suit specific loss circulation events as required.

The other key advantage of using 3D printing is that it allows the manufacture to be done local to where application is required.

The Lost Circulation Shape is designed using standard CAD software and saved in the standard 3D printing .STL file format.

The Lost Circulation Shape has been designed specifically for 3D printing manufacture such that no additional print support structures and so no 3D printing post processing is required.

The size tolerances and surface finish on the shapes has also been made non-critical.

These design considerations greatly facilitate the quality control and acceptance criteria of the Lost Circulation Shape (figure 2) such that simple email communication of the .STL file to any 3D printing factory that has the appropriate printers is all that would be required to produce the Lost Circulation Shapes without the need for prior knowledge or trial manufacture runs.

The Lost Circulation Shape form is relatively simple. But if it was manufactured using traditional manufacturing techniques, making the hollow chamber and perforations would require complex multi-cavity very expensive mold tools.

The current development of Lost Circulation Shapes is at a field-testing phase requiring unit volumes of thousands. Comparison of unit costs between 3D printing and the investment of mold tools for traditional manufacturing makes 3D printing the more economic choice for manufacture.

When the prototype testing of the Lost Circulation Shapes is complete and the use of the shapes becomes an operational requirement, the volumes would probably increase to tens of thousands.

This significant volume requirement would justify the use of traditional volume manufacture processes if considering only unit cost of manufacture. Although the advantages of multiple site manufacture and design change flexibility would be lost. The perceived value of these unique 3D printing advantages may justify the higher unit cost and continued use of 3D printing.

Associated Companies
» Aramco

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