Biomass used in new oil field drilling fluid

• Baton Rouge

A team of LSU AgCenter researchers led by Qinglin Wu is developing drilling fluids that include a component made from nontoxic biomass materials.

The research is funded by a $346,000 grant from the U.S. Department of Agriculture Forest Service and the U.S. Endowment for Forestry and Communities and a $187,000 grant from the Louisiana Board of Regents through its Industrial Tie program and an oil service company.

Wu said the drilling fluid will consist of nanocellulose made from trees or other biomass material, such as sugarcane bagasse and straw. Fibers from trees and other biomass are made of tiny cellulose crystals with a diameter about 10,000 times smaller than the diameter of a human hair.

Combined chemical hydrolysis and mechanical shearing have been used to isolate these tiny crystals, generally known as nanocellulose (NC). This material is very stiff and lightweight, and it has eight times the tensile strength of steel.

"There is a need for developing a new generation of smart drilling fluids with key additives from abundant, inexpensive, sustainable and biodegradable materials that will feature more environmentally friendlier features," Wu said.

The drilling fluid is a critical component during oil and gas exploration, a multi-billion-dollar business in the U.S. The fluids assist in moving drill cuttings to the surface and help cool the drilling pipes and drilling bits. The fluid also reduces friction, which helps lower drag on the drill bits during drilling.

There are two main problems affecting the performance of drilling fluids that Wu and his team are attempting to overcome.

About 30 percent of the oil and gas produced globally occurs in fields made up of gypsum layers and salt rocks. Drilling through gypsum causes a deterioration in the performance of drilling fluids because of the chemical reaction caused by the high concentration of sodium and calcium ions.

The second obstacle is related to the high temperatures associated with drilling. In deep reservoirs, temperatures can reach as high as 300 degrees Fahrenheit, which reduce the effectiveness of the fluids.

Wu's team is using surface-modified NC material to combat both problems. Chemicals grafted on the surface of the tiny NC material attract salt ions in the fluid, preventing them from bonding to other key components of the fluid and eliminating their negative effect on fluid properties.

The cost of producing this drilling fluid is high because of the cost of NC material. "But the cost for making the needed NC material is coming down significantly as industry is building larger manufacturing plants," Wu said.

Besides being environmentally friendly, Wu said, the NC-based material has another advantage. "Because it is water-based, it can be mixed directly with water-based fluids. And it can also be used in oil well cement to improve the cement strength used during the cementing process of drilling operation," he said.

The NC-based material can be adjusted to accommodate the drilling situation and improve the performance of the fluid. The use of NC material can help control fluid properties such as viscosity, lower overall fluid solid content and improve solid carrying capacities of the fluid, Wu said.

An advantage for Louisiana is the state contains a high amount of the biomass needed to produce the NC additives. It has a robust forestry industry, and sugarcane is an important economic crop that produces a large amount of bagasse, the leftover plant material from sugarcane after it has been milled for cane juice used in sugar production.

Wu has done previous research related to oil and gas exploration. He was one of the lead developers of a lost-circulation control material called TigerBullets, which is also a wood-based material.

Major oil and oil service companies such as ExxonMobil, BP, Chevron and Schlumberger have added TigerBullets in their drilling operations, and it has been used in more than 400 wells throughout the world.