What does a CT scanner have to do with safer drilling operations? The answer may surprise you. Researchers at NETL are combining their unparalleled expertise with unexpected tools like CT scanners to investigate a material that prevents leaks and spills during oil and gas drilling operations—foamed cement.
To most people, cement is the material of buildings, roads, bridges, sidewalks, and security barriers. However, cement also plays a critical role in the safe recovery of oil and gas from wellbores beneath oceans and land sites around the world.
Foamed cements are ultralow-density systems that are used during oil and gas drilling operations to encase production tubes and prevent leaks and spills. The “foam” part of the cement is created by injecting inert gas into cement slurries to create millions of microscopic bubbles.
NETL’s foamed cement research has been recognized around the world as one of the best sources for reliable information about the performance of foamed cements in oil and gas wellbores. The increased use of foamed cement systems in high-stress environments makes understanding its stability in the wellbore vital.
In a brightly lit Pittsburgh laboratory, NETL’s Dr. Barbara Kutchko and her research team study a collection of atmospheric and field generated foamed cement samples. The samples are destined for a series of rigorous tests and observations all geared to determine which variation can best ensure quality, reduce cost, decrease waste, and support safer oil and gas recovery operations around the world under a variety of conditions.
Unstable foams can result in uncemented sections or channels in oil and gas wells. A stable foam provides the desired casing support when installed properly in the wellbore. The size and distribution of the bubbles that result from the injection of gases like nitrogen determines the stability of the cement. That’s why researchers closely examine samples to learn which variations work best for the conditions oil and gas producers face in the field.
NETL partnered with industry partners to investigate the properties of foamed cements at various pressures, shear rates, and foam qualities. Using NETL’s industrial CT scanner, Kutchko and her team provided 3D image data sets of bubble size distribution across a range of foam qualities. The research also considered foam stability at conditions that simulated various depths in the well—a unique approach because the study measured bubble size distributions using high-resolution 3D imagery under pressure.
The research provides industry with the knowledge to ensure safe operation of deep and ultradeep offshore wells in which foamed cement systems are used.
NETL’s recognized foamed cement expertise and capabilities also provided a critical service by working with the American Petroleum Institute (API) to determine if industry-developed protocols and testing standards for mixing foamed cement in the lab, truly reflect in-the-field processes and operations used to mix and pump the cement for wellbores.
Researchers tested field samples using NETL’s CT scanning facilities, which are capable of replicating the pressures of a wellbore. The CT scans provided data on real materials under real conditions, and the results showed that field samples did not look like the laboratory samples.
This research illustrated that the equipment used to generate foamed cement has a major impact on its properties. The data obtained by NETL can now be used by API to correlate lab performance with field behavior and help to rewrite the old standards. NETL will be presenting their research in a joint presentation with the API foamed cement work group at this year’s OTC (Offshore Technology Conference) in May.
NETL’s foamed concrete research is just one way the laboratory is in pursuit of technology solutions to enhance the nation’s energy foundation and protect the environment for future generations.