Oil recovery from unconventional media is often difficult. However, significant hydrocarbon resources can be found in fractured reservoirs. As the supply of oil from conventional reservoirs is depleted, fractured media will provide a greater proportion of the country's oil reserves. One example of such a resource is the Bakken shale, part of the Williston Basin in North and South Dakota and Montana. It is estimated that over 100-176 billion barrels of oil are present in the Bakken shale. However, due to the low permeability of the formation and the apparent oil-wet nature of the shale, production from this formation presents considerable problems.

Over the past several years, NETL-ORD has developed valuable experience in fractured-reservoir technologies, both for oil recovery and for carbon sequestration. A medical-grade X-ray CT scanner is available for imaging core samples that contain fluids, as well as changes in the samples as one fluid is swept by another. We have developed a naturally-fractured reservoir simulator, NFFLOW, which is able to model the migration of fluids within a fractured formation and the surrounding rock matrix. NFFLOW has been validated for gas fields, and is currently available for doing miscible oil recovery above the bubble point. Two-phase capabilities are being incorporated in the code and should be available for use this year, which will allow for water-drive modeling or CO₂-enhanced oil recovery.

As part of this project, we will cooperate in NETL's acquisition of core and formation fluid samples from the Bakken shale. If possible, these cores will be placed in the CT scanner to image the nature of the fractures within the shale and other reservoir rock, the composition of the shale, and the amount of oil locked up within the shale matrix. The core will then be exposed to floods of CO₂, water, and/or other fluids to test their ability to sweep the shale of its oil. Where possible, we will look for opportunities to couple experimental results with modeling of the fractured reservoir resource. For example, from flooding the cores that we receive with different fluids (e.g., water, CO₂, micellular polymers), we may be able to determine relative permeability information that can be used in the reservoir simulator.
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The current industry interest in gas and oil-bearing shale reservoirs has led NETL to re-assess the resource potential of black shale formations in the Appalachian Basin. The Eastern Gas Shales Project conducted by DOE in the late 1970's included over thirty cored shale gas wells with up to twenty wireline logs per well. A follow-on project funded by the Gas Research Institute cored and tested several additional wells in the shallower shale formations on the western side of the Appalachian Basin. Information from these projects has been archived on DVD by NETL, and provides a background for the current investigation of the Middle Devonian-age Marcellus Shale. The goals of this project are to assess the geological properties that control natural gas production from the Marcellus Shale and other gas shales in the Appalachian Basin. Using a geologic framework model to link gas productivity and brine geochemistry to the geology is expected to improve the predictability of these two parameters, which will help the often small drilling companies attempting to produce the gas, as well as local water resource agencies responsible for the disposal of the recovered water. Methodologies developed for the Marcellus Shale will be used for similar assessments of the Utica Shale and Genessee Shale in the future.
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As part of the continuing effort to develop a comprehensive database of information on historic research related to oil shale and tar sands, NETL has supported an effort to identify all of the sources of reports, samples and well data. The effort began over two years ago with the development of a comprehensive bibliography. The list has 18,000 references. There are additional references in the University of Utah Repository, an online database of oil shale and tar sand references strictly from the basins in Utah funded by NETL. The Piceance Basin of Colorado has additional industry reports that are currently stored in the basement of the library at the Colorado School of Mines. NETL is coordinating with all of the universities, state and federal agencies and industry to develop the most reliable references for future development of the resource.
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The EPACT Knowledge Management Database, KMD, is a central repository for Research and Development (R&D) results and products related to the recently implemented “Section 999 R&D Program.” Subtitle J, Section 999, of the Energy Policy Act (EPAct) of 2005, called for the establishment of an Ultra-Deepwater and Unconventional Natural Gas and Other Petroleum Resources Research and Development Program. The legislation identifies three program elements to be administered by a consortium under contract to the Department of Energy. Complementary research performed by the National Energy Technology Laboratory (NETL) is a fourth program element. NETL is also tasked with managing the RPSEA consortium. In addition to archiving the results of the Section 999 R&D Program, this repository will also include other related research products that have been generated by the traditional oil and gas research program at the NETL Strategic Center for Natural Gas and Oil (SCNGO).

This repository is envisioned as a “Web site portal” within the larger NETL Web site. The proposed features include an interactive map display capability and a feature that permits zooming in on high resolution images. Also, at least two “expert system” interactive problem solving features will need to be integrated into this portal. One of these, the Produced Water Information System (PWIS) is already in the process of being added to the NETL Web site. The other, a self-teaching expert system (SETES) for the analysis and prediction of gas production from fractured shales, is to be built by Lawrence Berkeley National Lab under one of the selected R&D projects administered by the Consortium.

The purpose of this Web site portal will be to provide a single place where users can find all of the results and products produced by the Section 999 R&D program, and more importantly, can locate information within this portfolio of products that they need, quickly. Accordingly, the Web site must be simple and easy to understand, easily navigable, quick to use, and comprehensive.
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The Ultra-Deep Single-Cutter Drilling Simulator (UDS) is to operate in Building 12 (B-12) at the NETL Morgantown site. The UDS provides a simulated drilling environment found at the bottom of ultra-deep wells, having conditions of High-Pressure and High-Temperatures typically encountered in wells having depths beyond 20,000 feet.

The UDS consists of a pressure vessel, a charge pump, circulating pump, heat exchanger, x-ray source and detector.

The test specimen is a rock core having maximum dimensions of 8” diameter x 12” long (cylinder shaped). This rock specimen will be attached to a sample holder on the bottom plug that is driven by hydraulic motor. This hydraulic system provides rotational motion in the x-y plane and linear displacement in the Z-direction. When the reaction column (Figure 2) is swung out of the way, the hydraulic system provides project personnel with the capability of lifting the pressure vessel off of the bottom plug very quickly. This is shown above in Figure 3 and Figure 4. The massive load frame, partially shown in Figure 2, is necessary to contain the thrust forces generated by the immense fluid pressure acting on the vessel ends.

The UDS machine will also have one or more “cutters” installed within the pressure vessel that contacts the rock specimen. The cutter is specified by the researcher in the test plan request, but will often be a 25 mm PDC (polycrystalline diamond cutter) disk, or a carbide roller cone, or a diamond-impregnated cutter. Whatever cutter is specified, it will be chemically inert in the UDS and will tend to have very high Hardness value.

The UDS machine will also be loaded with a liquid drilling fluid. This fluid will be prepared within the EDL by project personnel and will either be a water-base mud or an oil-base mud. The fluid will be compressed by the UDS to pressure up to 30,000 psi. Pressurizing to 30,000 psi from ambient pressure will likely cause non-negligible fluid compression in the liquid phase. Estimates project that the specific volume of the liquid will decrease by 7%. Since actual UDS volume is constant, more liquid must be injected by a positive displacement pump during the compression that initiates a UDS test. Since the approximate liquid capacity of the UDS is 5 gallons, a 7% addition translates to injecting approximately 0.3 gallons of new fluid to achieve maximum operating pressure. Dissolving solids in the liquid, which is typical in drilling fluid preparation, will have the tendency to decrease the compressibility of the fluid. Also, UDS testing at pressures less than the maximum operating pressure will decrease the amount of injected fluid.

The UDS will have motion controlled exclusively by a hydraulic system. This hydraulic system is pressurized by an electric motor. The UDS is heated by a heat transfer fluid. This heat transfer fluid is heated by electric resistance heaters, external to the UDS system. In-situ vessel heating via electric resistance heaters may be an option, pending feasible engineering design. The research program has charged this project to have capability to heat the drilling fluid at the center line of the pressure vessel to be 250 deg C (482 deg F). However, the pressure vessel was designed for a maximum operating temperature (i.e. temperature of the steel) of 550 deg F. The pressure vessel will not have external insulation, so it will have the tendency to operate near the mean temperature between the process temperature and the ambient air temperature. This is a very conservative situation and provides amble opportunity to push process fluid temperature higher without any additional engineering changes. The project does not wish to request authorization for operating temperature above 482 deg F at this time. The heat transfer fluid may be as high as 550 deg F. The pressure vessel itself (not including the load frame) consists of 6,000 lbs. of stainless steel, which represents a huge thermal heat sink. It will take many hours to pre-heat the vessel to operating temperature.

An X-ray system will be used during UDS testing to visualize the pressure vessel internals. The x-ray will be a micro-focus unit having a spot size on the order of 25 micrometers. The source and detector will have lead shielding around them. The very thick (t approximately 4 inch) steel vessel provides inherent shielding against radiation scattering from the sample inside the vessel.
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Drilling fluids or drilling muds are relatively complex materials based on water or oil. The drilling fluids have many functions. They are used to cool the drill bit, lubricate the rotating drill pipe, remove drill cuttings etc. The ultimate goal of this research project is to create a magnetically/electronically controllable drilling fluid that could, for example, not only provide cooling of the drill bits but also simultaneously offer significant nanoparticle based lubrication and also offer an independent control of rheology. In so doing we have developed a highly interdisciplinary program with the goal of developing nanoparticle based drilling fluids that would be smart and multifunctional in that the fluid compositions will be designed such that their transport and rheological properties can be adjusted themselves according to operation conditions or using an external field.

For this quarter, we have focused on the characterization of the laser-synthesized mixed-metal hydroxide (MMH) mud. It is based on mixed aluminum/magnesium hydroxide. When added to prehydrated clays (bentonite, laponiteRD..) the hydroxidex interact with the clay particles forming a strong complex that behaves like an elastic solid when at rest. Although MMH has great gel strength at rest, the structure is easily broken. So it can be transformed into a low-viscosity fluid that does not induce significant friction losses during circulation and gives good hole cleaning at low pump rates.

Additional accomplishments during this quarter also include work on laser synthesis of nanomaterials, on the viscosity of Fe₂O₃ – DW nanofluid and the theoretical study on the distribution of the velocity, pressure and drag forces in the flow field induced by the drilling oscillation motion. These accomplishments will be discussed in the Q2 project review.
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Objective: Identify potential performance gaps in currently available tubular materials in environments representative of ultra deep well drilling and sour environments.

Catastrophic materials failure is a concern associated with the high temperature, high pressure, sour environments encountered in deep well drilling applications. The pressures ( > 25ksi), temperatures ( > 450F) and corrosive ( > 5 ppm H2S) environment including corrosive slurries can result in sulfide-stress-cracking (SSC), fatigue cracking, significant wear/ corrosive wear of a variety of tubulars. Consequently, alloys utilized in these applications must possess fatigue strength, corrosion and wear/ corrosive wear resistance, and maintain required metallurgical properties and microstructural stability during operation.

Initial research will focus on 1) sulfide stress cracking (sour gas), and 2) wear-corrosion of tubular materials. Alloys to be investigated include conventional high strength pipe steels (e.g., N-80 (standard), C-90, G-105, XD-105, etc), "advanced" commercial alloys (e.g., nickel base and titanium alloys), and experimental alloys (e.g., NETL-high interstitial strengthen steels (HISSs), C-22HS). Research will also be initiated to develop computational approaches to fatigue behavior in deep well drilling environments.

Results will provide insight into the metallurgical and microstructural features that influence materials performance in these extreme environments, identifying existing materials that can be used in these applications, and guiding the development of new, cost effective materials, such as low cost CRA and casing and tool joint friendly coatings.
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Visibility impairment from regional haze is a significant problem in many areas of the U.S. Reduction of visibility is due to absorption and scattering of light by both particles and gases. Oil and gas production activities emit a variety of air pollutants such as PM2.5, NOx, SO2, VOCs and air toxics from multiple sources that include volatiles that escape from the wellhead during the drilling and production operations, production site product separation processing steps, combustion-based energy conversion point sources, etc.

Estimates of the impact of oil and gas exploration and production activities on regional air quality are generally based on air quality models that treat these activities in a given state as a single point source at worst, and at best, a series of generic point source pollution emitters. These inaccurate assumptions result in a very different air quality impact than would result from modeling the many small, widely dispersed sources that actually exist.

The impact of small-scale oil and gas production activities on local and regional air quality will be established through a combination of source-receptor modeling based on historic emissions literature, selected site air quality studies, and university partner based laboratory studies. Objectives for this task include identifying information gaps necessary to assess the impact of air emissions from oil and natural gas production activities and conducting assessment studies needed to develop models of the impacts on local and regional ambient air quality. Work this quarter has focused on evaluating air quality models such as PMF and CALPUFF for eventual modeling of visibility impacts and initial planning for conducting targeted on-site measurements of emissions from oil and gas production activities.
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