The current low oil prices, decline in drilling activity and focus on the bottom line has brought the effectiveness of drilling fluids management into the spotlight like never before.
In North America, for example, the drilling fluids market—valued at $4.3 billion in 2012—is expected to reach $7.2 billion by year-end 2019, according to industry anlysts Transparency Market Research.
With costs and the demand for drilling fluids predicted to continue to rise (despite the current low oil prices anddrilling activity), it’s clear that maintaining the quality and effectiveness of such drilling fluids is vital. Drilling fluids (or muds) play a crucial role in global drilling activity today—cooling and lubricating drillbits, carrying drill cuttings to the surface, controlling pressure at the bottom of the well and ensuring that the formation retains the properties defined for that well. Drilling fluids also need to be capable of keeping the cuttings in suspension when circulation is stopped to prevent the cuttings from accumulating on the bottom of the hole and causing pipe sticking.
How can drilling fluids be optimized to ensure maximum drilling efficiencies and performance on both offshore and onshore wells? A successful drilling fluids strategy and the effective separation of drilled solids from such fluids are crucial to protecting fluid quality and enhancing drilling performance.
Effective solids control
Any effective drilling fluids strategy is dependent on the efficient separation of drilled solids from the drilling fluids since rock particles and cuttings can vary in size and texture from fine silt to gravel. The higher the percentage of solids removed, the more efficient the drilling fluid will be.
Effective separation leads to operational, cost and environmental benefits for the operator. From an operational standpoint, better quality fluids and stable mud properties result in low equivalent circulating density (ECD), which is the density exerted by the circulating fluid against the formation.
It also preempts the risks associated with high ECD such as induced fractures, lost circulation and high fluid loss. Effective solids control also provides higher ROP, reduced risk of stuck pipe and improved wellbore stability.
From a cost perspective, better control of solids reduces the need for chemical additions to the fluids and minimizes the rates of dilution typically used when solids removal efficiency has not been optimized. With the cost of oil-based mud around $1,300 per cubic meter, the reduction in the cost of drilling fluid per offshore well can be as much as $150,000.
There is an additional cost as well as an environmental issue. Effective mud and solids separation leads to less waste and reduced costs. On the Norwegian Continental Shelf, for example, the treatment and disposal of drilling waste is conservatively
estimated at $1,580 to $1,750 per ton, and onshore costs for waste disposal are also significant.
From an environmental perspective, the Transparency Market Research report said that the drilling-fluid market is facing some tough challenges, such as “growing environmental concern toward the excessive usage of drilling fluids and their disposal, which can lead to dangerous contamination.”
At a time when there is an increased focus on the environmental impact of drilling (e.g., the recent and ongoing gas emissions in Los Angeles), reducing the volume of fluids lost is a critically important component in meeting environmental regulations while reducing the costs of disposal and treatment.
Addressing the challenges
Are today’s solid control technologies meeting these criteria and supporting drilling fluids management and drilling operations?
Previous solid control solutions have been based around shale shakers, where through vibrating G-forces solids are filtered out for discharge or treatment and then incorporated into the fluid system.
The high G-forces, however, tend to break down the drilled solids into finer particles, reducing the amount of solids that can be removed and increasing the solids content in the drilling fluids. High volumes of mud also are often lost with an increase in the volume of drilling waste generated.
It’s in answer to these challenges that Cubility has developed the industry’s first compact solids control system called the MudCube. The system eliminates using high levels of vibration to shake the fluids and solids apart.
Rather than relying on high G-forces to separate mud and drilled solids, drilling fluids are vacuumed through a rotating filter belt using high airflow to separate the cuttings from the fluid more effectively. The cleaned drilling fluids are then returned to the active mud system, and the drilled solids are carried forward on the filter belt and then discharged.
The separation capabilities of the system lead to better quality mud, more mud recycled back to the mud tanks to be reused for drilling and fewer chemicals. An operator and mud company, for example, reported the reduced use of premix chemicals brought savings of as much as $270,000 when using Cubility’s system.
The system also provides improved drilling efficiencies though stable mud properties and a decrease in nonproductive time (NPT). Furthermore, as mud properties are field-proven to be stable throughout the entire well when using the system, there are corresponding low-maintenance requirements to control drilling fluid properties with optimum parameters. This provides significant financial benefits to expensive onshore and offshore drilling rigs.
Drilling fluids are vacuumed through a rotating filter belt using high airflow to separate the cuttings from the fluid more effectively. The MudCube is a compact solids control system that eliminates using high levels of vibration to separate fluids and solids. (Source: Cubility)
The MudCube system provides improved drilling efficiencies though stable mud properties and a decrease in NPT. (Source: Cubility)
Offshore, onshore applications
Cubility recently signed a multimillion dollar deal on the Johan Sverdrup Field, one of the most important industrial projects in Norway over the next 50 years. Production startup on the field is scheduled for year-end 2019 and will consist of four platforms on which the MudCubes will be based.
In this case, the MudCube will provide Statoil with improved drilling efficiencies, lower mud consumption, reduced waste volumes and improved HSE.
Other offshore applications include the installation on the Maersk Gallant rig, where the system is addressing space utilization and HSE issues; the Peregrino A platform operated by Statoil Brazil, where the conventional solution was not controlling solids effectively when drilling in sand formations; and the Maersk Gallant rig.
In addition, the system is gaining considerable traction onshore North America, where the rise in drilling costs and declining oil price have increased the need to monitor the bottom line and put in place effective fluids management strategies.
To this end Cubility is in the final stages of kicking off multiple U.S. land trials with major operators and drilling contractors. Initial cost analysis based on various land operations from a fluid cost and disposal standpoint show the MudCube reducing overall operating expenses by as much as 15% per well.
This is a significant figure based on the fact that many U.S. land drilling operations are now based on pad drilling with multiple wells drilled much more quickly and efficiently.
The separation of drill cuttings and fluids is central to optimizing drilling performance and maintaining drilling fluid parameters.
Operators now have the tools for effective fluids management and solids control strategies at a time when a focus on the bottom line and drilling performance has never been more important.