DOE Award to Improve Environmental Protection in Disposing of Oil and Gas Drilling Wastes

Houston-Based Westport Technology Center to
Study Better Disposal Methods

Disposing of oily drill cuttings and fluids from oil and gas operations imposes major costs on producers, particularly those operating offshore. Producers in the Gulf of Mexico, for example, commonly must barge wastes to onshore disposal sites for treatment. This expense can often make economically marginal oil and gas formations unprofitable, and for the United States, this leads to increasing reliance on oil imports.

Now, Westport Technology Center (WTC) in Houston is preparing to study an approach that could offer an environmentally safe way to dispose of these wastes at significantly lower costs.

With a $293,000 grant from the Department of Energy's fossil energy research program, and more than $91,000 in private sector funding, WTC will carry out a series of laboratory investigations to determine whether drilling wastes can be safely injected into certain types of sand formations found both offshore and onshore. The key will be to ensure that the injection processes don't overstress the formations and create fractures that allow the waste materials to seep out.

WTC will be joined by Petrophysical Consulting Inc., comprised of faculty members of Stanford University's Rock Physics and Borehole Geophysics Group. The research project will be guided by an industry advisory board. The government's role in the effort will be overseen by the Energy Department's National Petroleum Technology Office in Tulsa, OK.

Researchers will focus on "unconsolidated" or "poorly consolidated" sand formations. These commonly found sediments are comprised of loosely or weakly bonded sand particles that lack the strong "cementing" of the sand grains found in typically hard, solid sandstone formations. Boreholes can be drilled into them for injecting wastes, but the formations are often more susceptible to stress and strain.

Disposing of large volumes of rock fragments and drilling fluids will necessitate fracturing these formations, therefore, oil and gas producers must have greater knowledge of how these formations will react to increased downhole pressure and other stresses created in the disposal operation.

To find out, WTC and Stanford researchers will apply their expert knowledge of "deformation" - the effects of stress on a rock formation - on rock samples prepared in the laboratory that simulate the grain sizes and sand/clay mixtures of the candidate reservoirs. WTC will use its rock testing system to measure reaction to stress and strain in the samples. Both dry samples and samples saturated with brine, oil and other fluids will be tested.

The Stanford group will investigate the primary mechanisms controlling deformation. For example, they will look at the various ways sand and clay mixtures react in response to changing stress, pressure, and movement in the formation.

From these studies, a computer model of the deformation process will be developed. Producers will be able to use the model to design environmentally acceptable injection strategies that meet the needs of an individual production operation.

Results from the project could play an especially significant role in future oil and gas operations in the Gulf of Mexico. In contrast to many onshore drilling operations where water-based drilling fluids can be used and disposed of inexpensively, certain formations in the Gulf can be damaged by water-based fluids. Drilling wells into these formations requires oil-based or expensive synthetic fluids. Environmental regulations ban the disposal of these fluids into the ocean.

If techniques can be developed to inject these wastes into underground formations - rather than the costly alternative of barging them - more offshore oil and gas reservoirs could become economically attractive. The WTC study is a key step toward ensuring that such a disposal technique can be applied predictably and in a way that assures environmental protection.

- End of TechLine -

For more information, contact:
Hattie Wolfe, U.S. Department of Energy, Office of Fossil Energy Headquarters, (202)586-6503; e-mail address: hattie.wolfe@hq.doe.gov

Technical Contact:
Herb Tiedemann, Technology Transfer Officer, National Petroleum Technology Office, (918)699-2017; e-mail address: htiedema@npto.doe.gov

Company Contact:
Dr. Ali Mese, Westport Technology Center, Houston, (713)479-8444; e-mail address: amese@ddpo.com.