Drilling fluids' global reach

Members of ExxonMobil Chemical's Escaid team include (from left) Elissa Sterry, Intermidiates vice president; Abdiel Urriola, global fluids market planner; Ronan O'Flaherty, global fluids marketing manager; Dan Helgesen, Americas fluids marketing manager; and Ronald Hill, fluids marketing technical support scientist.

Imagine trying to dig a 3-footdeep hole for a fence post with no way of removing the loose dirt from the hole. You wouldn’t get very far.

So how do oil and gas drillers remove rock cuttings while boring to depths that sometimes reach several miles? They circulate specialized fluids known as drilling muds down the drill shaft to capture the cuttings and carry them to the surface. Such fluids have been used since the earliest days of oil and gas production, and they serve several purposes. Besides bringing cuttings to the surface, drilling muds cool, clean and lubricate the drilling bit and help ensure that underground fluids such as oil, gas or water do not flow into the wellbore — at the same time preventing the wellbore from collapsing.

Like so much else in today’s drilling industry, modern drilling fluids are far more technically advanced than anything used a century ago. Back then, drilling mud was a simple mixture of clay and water that produced a thick slurry. The content of all muds was more or less the same.

“Today we have a wide range of drilling fluids available, so we can select the product that best suits the specific needs of each well,” explains Tom Upton, operations support manager for ExxonMobil Development Company’s global drilling organization. “Our selection is based on such factors as worker health and safety, the depth and angle of the wellbore, formation pressures and environmental guidelines affecting the area. Using the ideal fluid for each well is a key consideration in our success.”

Deeper drilling brings new challenges
Much of ExxonMobil’s drilling activity today occurs in environments that present far more complex engineering challenges than was the case 25 years ago. “We’re doing a lot of what we call ‘extended-reach’ drilling,” says Upton.

“Many of our wells today are drilled at steep angles to access resources located several miles from the drilling platform or surface location. These wells may reach total measured depths of greater than 30,000 feet. So our drilling equipment is subjected to very high friction loads. When we drill at steep angles, the geologic formations the wellbore passes through are often less stable than when we drill shallower and straighter wells. That makes the role of drilling fluids all the more critical.”

One of the industry’s premier drilling base fluids — and one ideally suited for use in extended-reach drilling — is the Escaid portfolio of products from ExxonMobil Chemical Company. “We now offer four grades of Escaid, and collectively they meet the needs of almost any drilling situation,” says Elissa Sterry, vice president, Intermediates, ExxonMobil Chemical. “Escaid is a key component in many of the muds used by ExxonMobil and numerous other oil and gas companies around the world.”

Safer and friendlier for the environment
Environmental and worker-safety regulations affecting drilling fluids are much stricter today than 25 years ago, with the result being development of fluids that are safer to handle and friendlier to the environment.

Escaid fluids are dearomatized (low odor) mineral oils and, in combination with state-of-the-art cuttings treatment, provide drilling fluids with minimal environmental impact. ExxonMobil Development Company has a strong commitment to minimizing its environmental impact from drill cuttings. This is reflected in the ExxonMobil drill cuttings discharge standard, in which best-available technology is used to reduce the oil on cuttings before the cuttings are discharged — in areas that allow such disposal.

Escaid base fluids are sold to mud companies that mix the fluids with other materials to produce drilling mud. Such materials include clay, water, salt, weighting agents and other specialized chemicals. Escaid fluids comprise nearly half of the resultant drilling mud. A single development well can require more than 5,000 barrels of drilling mud.

“It’s very common for mud to be used many times before being disposed of,” explains Sabine Zeilinger, drilling fluids engineer for ExxonMobil Development Company. “After a drilling fluid is used in a drilling operation, it moves to an adjacent processing facility where fines and solids are removed, and the fluid is cleaned and recycled for yet another well.”

Many operators, including ExxonMobil, often lease rather than purchase drilling mud, a practice that encourages recycling and thereby reduces the drilling operation’s environmental footprint.

To the drilling engineer, one of Escaid’s finest features is its low viscosity (thickness), which is not much greater than water. The lower the viscosity of a drilling fluid, the less effort is required to move the fluid with the cuttings to the surface. This is especially important in extended-reach drilling that requires tremendous horsepower to circulate the fluid in a hole that may be 5 miles long. Other key Escaid advantages include its low-temperature pour point so it won’t freeze and, more importantly, its low-aromatic content, which significantly reduces environmental toxicity and risk of vapor exposure to personnel.

In June, ExxonMobil Chemical introduced a new product, Escaid 120 ULA (Ultra-Low Aromatic). Designed for the most demanding working temperature and pressure conditions, the new fluid was developed using proprietary catalyst hydrogenation technology. Escaid 120 ULA provides the industry a drilling fluid with extraordinarily low aromatic content, less than one-hundredth of one percent. Pierre-Yves Guyomar, senior technical advisor in Brussels, agrees that this grade complements the existing portfolio of Escaid fluids successfully serving Europe, Central Asia and Africa.

Global availability for competitive advantage
To better serve the drilling industry, Escaid base fluids are available globally, with some regional variations to meet specific needs. Escaid base fluids are produced at ExxonMobil plants in the United States (Baytown, Texas), South America (Paulinia, Brazil), Europe (Antwerp, Belgium, and Trecate, Italy) and Asia (Thailand and Singapore).

One geographic area experiencing rapid growth in the use of Escaid-based drilling muds is the Asia-Pacific region, where ExxonMobil has recently completed an expansion of the Singapore fluids manufacturing facility.

Chee-Peng Pek, a Singaporebased senior sales engineer for ExxonMobil Chemical, says Escaid has played a key role in the drilling success at ExxonMobil’s Sakhalin-1 Project in Eastern Russia. “And over the last few years we’ve seen growing demand in Malaysia, Thailand, India, China and the Philippines,” she says. “Having Escaid fluids available in Singapore makes for a shorter supply chain, and that allows us to meet our customers’ requirements faster and at lower cost.”

Recent oil discoveries offshore Brazil — including deepwater discoveries — have generated rising demand for Escaid fluids in that country. “The high quality of our products and their availability right here in Brazil are major reasons for the demand growth,” says Alberto Bittar, ExxonMobil Chemical Company’s fluids sales manager for the Americas South region.

“Drilling mud companies want global suppliers that can provide technical expertise to help them meet the combination of strict environmental regulations and complex drilling requirements,” notes Sterry.

“They also want an assured supply and consistent quality. With so much drilling activity occurring today in remote environments, having Escaid fluids available worldwide gives us a key competitive advantage,” she says. “We leverage that advantage with a global team that includes commercial, technical and marketing staff in Asia, the Americas and Europe. So our Escaid business benefits not only our chemical company, but our development company as well. For ExxonMobil shareholders, that’s a good combination.”