Magnificent mud

Technical advances have transformed drilling fluids from basic mud into critical chemical collaborators.

Drilling fluids are at the very heart of a healthy, productive well. The mud business, as it is rather simplistically still referred to, can literally be the vital key to ensure a smooth drilling operation  & a productive well or, be the cause of an unstable wellbore and a catastrophic well blow-out.

Meeting the challenges of drilling deeper, more intricate, and altogether more complex drilling environments are the inglorious fluids that garner little attention, but have quietly been undergoing a hi-tech evolution.

Ray Grant, business development manager, Middle East & Asia Pacific Region, for Baker Hughes Drilling Fluids, speaks exclusively to Oil & Gas Middle East in a tumultuous time for the upstream industry.

With a remit covering Egypt in the West to China and Australia in the East, Grant is one of the most travelled men in the industry, and as such, has been acutely aware of the impact the oil price collapse has had since October.

"I've been in the industry through three distinct cycles, and it's still surprising to see how quickly the industry can turn from being very upbeat to very concerned," says Grant. "This particular cycle is one that is not just an oil and gas industry downturn. The whole world is in recession, and at this stage it is uncertain how quickly we can pull through this."

The demand for drilling fluid is a key barometer to the health, and wealth, of the upstream industry. "Clearly, the demand for drilling fluid is driven by rig activity, so we monitor that very carefully and look for trends. If we see rig activity on the rise we have to anticipate an increase in demand for drilling fluid, so we can also gauge a demand drop off early."

"New exploration drilling activity and field development is only part of the fluids picture though, and increasingly reservoir remediation has become a key focus area for Baker Hughes Drilling Fluids worldwide," explains Grant.

"From experience, we expect to see a shift away from expensive exploration drilling activity in the short term, towards more development and workover projects. At Baker Hughes we're able to adapt quickly to any changes in market activity and we will continue to provide the equipment, tools, chemicals and engineering expertise to meet our customers' expectations."

Tech focus

Baker Hughes Drilling Fluids have an extensive range of proprietary chemicals which are produced under license all around the world. Generally speaking, aside from the base fluid, the main constituent in a drilling fluid is the mineral, Barium Sulphate which is commonly referred to as Barite in the industry.

Some 77% of all mined Barite worldwide is used as the principal weighting agent for drilling fluids in oil and gas exploration & development. However, other uses include electronics, TV screens, rubber, glass ceramics and the paint industry.

"Barite is a very dense mineral which is chemically inert. These two key properties make it ideal to add to the drilling fluid and increase density. It's ground to a very small particle size so that it can be held in suspension in the fluid & provide the hydrostatic pressure required to stabilize the wellbore while drilling," explains Grant.

"As you drill deeper through sedimentary layers, these can be abnormally pressured by the overburden and so it's vital to ensure that the density of the fluid is carefully monitored and sufficient hydrostatic pressure is applied to prevent any wellbore collapse," explains Grant.

"Reservoir fluids can also be pressured and so it's vital to ensure that the drilling fluid column density is sufficient to control any reservoir pressure, otherwise you can experience an uncontrolled flow of hydrocarbons to the surface which could cause a catastrophic blow-out and the potential loss of life & the drilling rig."

The drilling fluid should provide a barrier between the wellbore and the formation around it. The fluid filter cake acts like a protective casing to stabilize the sedimentary layers which have been drilled until a steel casing  string is run into the wellbore.

"What we're trying to do with the fluid is balance its chemistry with that of the formations drilled to help ensure good borehole stability. Water will cause the hydration of any clay or shale formations causing them to collapse. With the right chemicals & a well engineered drilling fluid design, there shouldn't be any reaction which can cause borehole instability," says Grant.

Chemistry aside, the drilling fluid provides a structural support to the well itself. The deeper a hole is drilled through any particular section & the longer the open hole section, the greater the chance there is of it becoming unstable and collapsing.

The drilling fluid is made up of various chemicals which are designed to maintain optimum physical and chemical properties, so when drilling long, deep sections the formations drilled remain in a stable condition.

A further important function of a good drilling fluid is to have adequate viscosity and the optimized rheological properties required to convey the drilled cuttings to the surface where they're discarded and the drilling fluid is recycled.

"As you're drilling deeper the fluid is pumped at optimum hydraulic flow rates to convey the drilled cuttings up the annulus and ensure good hole cleaning," adds Grant.

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