Basalt Pilot Overview

Introduction:
Continental flood basalts represent one of the largest geologic features on the planet and exist in many regions in the U.S. and worldwide. Basalt rocks were formed as lava flows cooled on the earth’s surface millions of years ago. Due to their vast presence and geochemical makeup, basalt formations are promising locations for the large-scale storage of CO₂. In 2005, the U.S. Department of Energy awarded the BSCSP funding to conduct a small-scale injection of CO₂ into basalt rocks. The project is a partnership between BSCSP, Battelle and Boise Inc. to take promising laboratory results for capturing and permanently storing CO₂ to the next testing step – a field test on Boise property near Wallula, WA (Fig.1). The efforts consist of site characterization activities to be followed by injection of 1000 tons of CO₂, provided site characterization data demonstrate the feasibility and safety of doing so and a permit for the injection is approved by the Washington State Department of Ecology. Public outreach has been an important component of this project in order to share project information, address peoples’ questions or concerns and obtain input on the project from community members.

Objectives:
The primary goal of the research is to conduct a small scale carbon sequestration project in deep basalts of the Columbia River Basalt Group (CRBG) (Fig.2). The research is one of the first projects in the world to assess the viability and capacity of deep basalt formations as an option for geologic sequestration. The investigators are: 1) addressing the technical issues associated with injection, fate, and transportation of supercritical CO₂ in a deep basalt formation; 2) participating in public outreach activities with the community and industry leaders; and 3) working with state regulators to ensure timely support of necessary regulatory procedures and permitting processes.

Methods:
The scientists working on this project are taking several steps to ensure that the project is done safely and that they are using the best available technologies to obtain the most accurate information. To select the best zone for injection, the scientists must first learn about the formation’s thickness, permeability, porosity, mineral makeup, and caprock properties. Similar to a layered cake, the Grande Rhonde basalt is composed of ancient hardened lava flows with very dense layers in between the more porous layers (Fig.3). The deep porous layers contain very small holes that are ideal for storing CO₂. When the injected CO₂ flows through the basalt layer, it mixes with water trapped in the holes and solidifies into calcium carbonate, or limestone, permanently storing the CO₂ underground. The dense layers located above the more porous layers would serve as a caprock, keeping the CO₂ from migrating to the surface.

Data Collection - Characterizing the basalt rocks and determining site suitability for the pilot test was the first step of the project. This was done by collecting and analyzing seismic data which is a technique to delineate geologic features, explore subsurface environments, and identify major geologic structures. Using seismic data from two Vibroseis (“Thumper”) trucks, researchers examined a four mile swath of land located near the field site (Fig.4). Strong vibrations produced by the trucks generated underground shock waves that transmitted valuable data back to the truck’s sensors. The properties of the wave, such as amplitude, frequency and wavelength enable researchers to understand the properties of the rock deep below the surface and to select the ideal spot to drill a well. From the seismic data, the scientists learned that an extensive basalt flow extends 8,000 feet underground. Further testing determined that the basalt formation is absent of major geologic structures (i.e. faults, fractures, etc.).

Drilling - Drilling began on January 14, 2009 and reached a depth of 4,110 feet on April 6, 2009. Rock samples and basalt cores collected during drilling provided researchers with data on the rock layers and geochemistry of the formation. The information obtained was used to select the injection zone, complete the well design, and plan other logistical details.

Hydrologic Tests – A critical step was to characterize the groundwater of the Grande Rhonde basalt and surrounding rock layers. The hydrologic tests were an important part of the permitting process. In order to avoid impacting underground aquifers, the surrounding groundwater was analyzed for chemistry and mineralogical content. To protect groundwater, carbon sequestration can only be permitted in areas where the groundwater is dirty or can’t be used for any other purpose.

Microbiological Studies - Over the previous 20 years, scientists have been studying the presence of microbes in the subsurface and how they respond to external disturbances. At the field site, researchers are interested in studying the impact of CO₂ injection on the microbial communities at the basalt pilot site. Models predict that injected CO₂ will decrease pH levels and may alter the formation chemistry. While some microbes may become stressed by increased levels of CO₂, other microbes may flourish under the new environmental conditions. This component of the study is expected to answer key questions about how microbes will respond when exposed to CO₂ and what role microbes may play in basalt formations chemistry.

Imagery - The scientists used special tools during the drilling process to capture images with a Formation Micro Imager (FMI) and a wireline imaging service. The images provided important information on the structural and stratigraphic components of the basalt formation. Also known as image logs, this type of data helped the researchers identify potential CO₂ injection zones – rock layers without areas of stress and/or fractures.

Project Findings:

To date, data has been collected, a well has been drilled and a permit to inject CO₂ has been submitted to the Washington Department of Ecology. The results from the seismic work represent the first known success of surface-based imaging of basalt geology. In addition, the Wallula pilot represents the first detailed-characterized, reconnaissance-level well for deep Columbia River basalt formations within this region of the State. The following paragraphs describe what the scientists have learned from the study so far.

Injection Zone Characteristics - The scientists identified three zones within the Grande Rhonde basalt formation as suitable to inject CO₂. All three zones are located between 2,716 to 2,910 feet and are referred to as part of the Slack Canyon Member (Slack Canyon flow #1, Slack Canyon flow #2, and the Ortley flow) (Fig. 5). Each flow contains a top layer, known as a “caprock,” which will act as a lid and effectively seal the sequestered CO₂ from leaking to the surface. Each caprock measured between 35 and 99 feet and was tested for pressure and injection flow-rate capabilities. This was important to determine the threshold and permeability properties of each caprock layer.

Hydrologic Testing - Results from groundwater sampling showed that the hydrochemical properties of the Wallula pilot site were similar in character to other basalt groundwaters within the region. Basalt groundwaters generally exhibit elevated levels of pH, flouride, sodium and other minerals due to the geochemical evolution of the surrounding area, such as reactive processes to volcanic phases and other hydrothermal variables. Understanding the waters in basalt formation was an important step in the monitoring and permitting process for the State of Washington. The results of the water sampling indicated elevated levels of flouride in the groundwater that exceeded recommended standards and that carbon sequestration could take place.

Discussion and Future Work: Based on work done to date, three zones were identified within the Grande Rhonde formation as suitable to inject CO₂. The injection zones provide a unique and attractive opportunity to study the rock behavior of three inter-connected injection zones and their caprocks. Prior to the actual injection of CO₂ into the basalt flow, the BSCSP team is performing the following activities:

Simulation Modeling - Based on the information collected, a computer simulation model was developed to predict CO₂ injection scenarios for the Grande Rhonde Basalt. The simulated models provided important information on future injection procedures, monitoring and verification activities, and other issues related to the safe transportation and storage of supercritical CO₂.

Injection Phase - The injection phase will begin after issuance of a permit from the Washington Department of Ecology. During this phase, the scientists will focus on: 1) safely injecting 1000 tons of supercritical CO₂ and several tracers to identify CO₂ presence into the basalt formation, 2) tracking the injected CO₂ plume within the reservoir zone, and 3) assessing for leakage within the formation by using geophysical sensors and standard hydrologic pressure monitoring systems. The CO₂ will be transported by rail from the supplier directly to the field pilot study area. The CO₂ will be maintained at uniform temperature within a storage vessel during the injection phase. Efforts will be implemented to maintain a continuous, constant CO₂ injection rate. Based on simulation models and analyses, the CO₂ injection phase will likely be completed within a two week period. A large number of tracer elements will be incorporated and administered at the beginning and near the end of the injection phase for detection and monitoring of CO₂ presence and flow.

Monitoring Program - Scientists are developing detailed procedures to be followed during and after the CO₂ injection to monitor the injected gas and other important variables. In order to monitor the unlikely event of leakage of CO₂ from the subsurface, a high tech sensor system (Eddy Covariance) will be installed (Fig. 7). Unlike gas probes and other standard monitoring methods, the Eddy covariance method provides broad coverage and is able to monitor a wide area. This technique is an established approach that has been used for years to measure the flux of heat and other variables between the atmosphere and the earth’s surface. The CO₂ flux, or how much CO₂ is released over time, can be determined by monitoring wind speed, atmospheric CO₂ concentration levels, temperature and humidity. A datalogger will record incoming data from the sensors and any changes in CO₂ concentrations at the surface. In addition, soil probes and water chemistry tests will be performed to determine the stability and permanence of the sequestered CO₂ deep underground.

Pre-Closure Characterization:
A period of 12 to 24 months is anticipated for the injected CO₂ to reside and react with the basalt reservoir before initiating pre-closure characterization activities. The primary objective of this phase is to study and identify geochemical and hydrological reactions to the injected CO₂ within the reservoir. Pre-closure characterization activities include: drilling and retrieving borehole samples from the injection zone, conducting a suite of geophysical surveys and comparing results to pre-injection surveys, and performing a series of comparative hydrologic tests between pre- and post-injection phases.

Public Outreach Efforts:
Engaging the public and key stakeholders is a critical component of the project. The outreach efforts began in July 2007 and involved engaging tribal members and a broad range of stakeholders including local-elected officials, business leaders, local citizen groups, media sources, and other stakeholders in the region (Fig. 8). Boise and Battelle worked closely together to develop and execute a joint stakeholder involvement plan, including:

• providing up-to-date information on the project’s progress,
• identifying people and organizations in the community with vested interests in the area and proactively approaching them to elicit key concerns and questions about the project,
• working extensively with various stakeholders to resolve issues and conflicting goals and,
• participating with a broader network of people, organizations and other groups in the region in order to establish a framework to understand the larger implications of carbon sequestration and climate change.

Meetings with community leaders and local citizens were conducted to describe and inform participants of the partnership’s intentions and objectives. Key media outlets were also contacted and invited to visit the site and meet with site coordinators. In addition, open houses and tours were offered to interested focus groups in the region. Later, a geology class from the local college toured the laboratories and drilling site, resulting in summer intern positions and an increased awareness of carbon sequestration knowledge and understanding of the project’s goals.

To download a copy of the 2009 Phase II Basalt Pilot Factsheet, click here.

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