Yongchun Tang

Improved Processes to Remove Naphthenic Acids

In the second year of this project, we continued our effort to develop low temperature decarboxylation catalysts and investigate the behavior of these catalysts at different reaction conditions. We conducted a large number of dynamic measurements with crude oil and model compounds to obtain the information at different reaction stages, which was scheduled as the Task2 in our work plan. We developed a novel adsorption method to remove naphthenic acid from crude oil using naturally occurring materials such as clays. Our results show promise as an industrial application. The theoretical modeling proposed several possible reaction pathways and predicted the reactivity depending on the catalysts employed. From all of these studies, we obtained more comprehensive understanding about catalytic decarboxylation and oil upgrading based on the naphthenic acid removal concept.

Atmospheric CO2 Monitoring Systems

Monitoring for atmospheric CO 2 concentrations may be an integral part of any subsurface storage project. Several CO 2 measurement methods may be used to meet the monitoring objectives of assuring there are no large leaks at the surface that might pose a health risk and verifying that the injected CO 2 remains trapped below the Earths surface. Options include remote sensing from satellites or aircraft, open path instruments that can sample over significant distances, and a network of conventional fixed-point detectors. NASA indicates satellite surveys might be useful for a “global” view of CO 2 . Aircraft surveys may be a fast means to collect data near ground level, but this is only practical in an infrequent basis. Instruments located near ground level that are based on open path sampling may offer the most efficient means to monitor long term over a large surface area. They could have the capability to detect increases of just a few percent of CO 2 above normal background, over a sample path of tens of meters, and continuously with unattended operation. Many different commercial fixed-point units based on infrared (IR) spectroscopy are available. These detectors may be better suited to monitor sensitive, high-risk points of leakage rather than be deployed in a network to monitor large surface areas.

LOWER COST METHODS FOR IMPROVED OIL RECOVERY (IOR) VIA SURFACTANT FLOODING

This report provides a summary of the work performed in this 3-year project sponsored by DOE. The overall objective of this project is to identify new, potentially more cost-effective surfactant formulations for improved oil recovery (IOR). The general approach is to use an integrated experimental and computational chemistry effort to improve our understanding of the link between surfactant structure and performance, and from this knowledge, develop improved IOR surfactant formulations. Accomplishments for the project include: (1) completion of a literature review to assemble current and new surfactant IOR ideas, (2) Development of new atomistic-level MD (molecular dynamic) modeling methodologies to calculate IFT (interfacial tension) rigorously from first principles, (3) exploration of less computationally intensive mesoscale methods to estimate IFT, Quantitative Structure Property Relationship (QSPR), and cohesive energy density (CED) calculations, (4) experiments to screen many surfactant structures for desirable low IFT and solid adsorption behavior, and (5) further experimental characterization of the more promising new candidate formulations (based on alkyl polyglycosides (APG) and alkyl propoxy sulfate surfactants). Important findings from this project include: (1) the IFT between two pure substances may be calculated quantitatively from fundamental principles using Molecular Dynamics, the same approach can provide qualitative results for ternary systemsmorexa0» containing a surfactant, (2) low concentrations of alkyl polyglycoside surfactants have potential for IOR (Improved Oil Recovery) applications from a technical standpoint (if formulated properly with a cosurfactant, they can create a low IFT at low concentration) and also are viable economically as they are available commercially, and (3) the alkylpropoxy sulfate surfactants have promising IFT performance also, plus these surfactants can have high optimal salinity and so may be attractive for use in higher salinity reservoirs. Alkylpropoxy sulfate surfactants are not yet available as large volume commercial products. The results presented herein can provide the needed industrial impetus for extending application (alkyl polyglycoside) or scaling up (alkylpropoxy sulfates) of these two promising surfactants for enhanced oil recovery. Furthermore, the advanced simulations tools presented here can be used to continue to uncover new types of surfactants with promising properties such as inherent low IFT and biodegradability.«xa0less

IMPROVED PROCESSES TO REMOVE NAPHTHENIC ACIDS

In the first year of this project, we have established our experimental and theoretical methodologies for studies of the catalytic decarboxylation process. We have developed both glass and stainless steel micro batch type reactors for the fast screening of various catalysts with reaction substrates of model carboxylic acid compounds and crude oil samples. We also developed novel product analysis methods such as GC analyses for organic acids and gaseous products; and TAN measurements for crude oil. Our research revealed the effectiveness of several solid catalysts such as NA-Cat-1 and NA-Cat-2 for the catalytic decarboxylation of model compounds; and NA-Cat-5{approx}NA-Cat-9 for the acid removal from crude oil. Our theoretical calculations propose a three-step concerted oxidative decarboxylation mechanism for the NA-Cat-1 catalyst.

Atmospheric CO 2 Monitoring Systems

Monitoring for atmospheric CO 2 concentrations may be an integral part of any subsurface storage project. Several CO 2 measurement methods may be used to meet the monitoring objectives of assuring there are no large leaks at the surface that might pose a health risk and verifying that the injected CO 2 remains trapped below the Earths surface. Options include remote sensing from satellites or aircraft, open path instruments that can sample over significant distances, and a network of conventional fixed-point detectors. NASA indicates satellite surveys might be useful for a “global” view of CO 2 . Aircraft surveys may be a fast means to collect data near ground level, but this is only practical in an infrequent basis. Instruments located near ground level that are based on open path sampling may offer the most efficient means to monitor long term over a large surface area. They could have the capability to detect increases of just a few percent of CO 2 above normal background, over a sample path of tens of meters, and continuously with unattended operation. Many different commercial fixed-point units based on infrared (IR) spectroscopy are available. These detectors may be better suited to monitor sensitive, high-risk points of leakage rather than be deployed in a network to monitor large surface areas.

Cost Effective Surfactant Formulations for Improved Oil Recovery in Carbonate Reservoirs

This report summarizes work during the 30 month time period of this project. This was planned originally for 3-years duration, but due to its financial limitations, DOE halted funding after 2 years. The California Institute of Technology continued working on this project for an additional 6 months based on a no-cost extension granted by DOE. The objective of this project is to improve the performance of aqueous phase formulations that are designed to increase oil recovery from fractured, oil-wet carbonate reservoir rock. This process works by increasing the rate and extent of aqueous phase imbibition into the matrix blocks in the reservoir and thereby displacing crude oil normally not recovered in a conventional waterflood operation. The project had three major components: (1) developing methods for the rapid screening of surfactant formulations towards identifying candidates suitable for more detailed evaluation, (2) more fundamental studies to relate the chemical structure of acid components of an oil and surfactants in aqueous solution as relates to their tendency to wet a carbonate surface by oil or water, and (3) a more applied study where aqueous solutions of different commercial surfactants are examined for their ability to recover a West Texas crude oil from amorexa0» limestone core via an imbibition process. The first item, regarding rapid screening methods for suitable surfactants has been summarized as a Topical Report. One promising surfactant screening protocol is based on the ability of a surfactant solution to remove aged crude oil that coats a clear calcite crystal (Iceland Spar). Good surfactant candidate solutions remove the most oil the quickest from the surface of these chips, plus change the apparent contact angle of the remaining oil droplets on the surface that thereby indicate increased water-wetting. The other fast surfactant screening method is based on the flotation behavior of powdered calcite in water. In this test protocol, first the calcite power is pre-treated to make the surface oil-wet. The next step is to add the pre-treated powder to a test tube and add a candidate aqueous surfactant formulation; the greater the percentage of the calcite that now sinks to the bottom rather than floats, the more effective the surfactant is in changing the solids to become now preferentially water-wet. Results from the screening test generally are consistent with surfactant oil recovery performance reported in the literature. The second effort is a more fundamental study. It considers the effect of chemical structures of different naphthenic acids (NA) dissolved in decane as model oils that render calcite surfaces oil-wet to a different degree. NAs are common to crude oil and are at least partially responsible for the frequent observation that carbonate reservoirs are oil-wet. Because pure NA compounds are used, trends in wetting behavior can be related to NA molecular structure as measured by solid adsorption, contact angle and our novel, simple flotation test with calcite. Experiments with different surfactants and NA-treated calcite powder provide information about mechanisms responsible for sought after reversal to a water-wet state. Key findings include: (1) more hydrophobic NAs are more prone to induce oil-wetting, and (2) recovery of the model oil from limestone core was better with cationic surfactants, but one nonionic surfactant, Igepal CO-530, also had favorable results. This portion of the project included theoretical calculations to investigate key basic properties of several NAs such as their acidic strength and their relative water/oil solubility, and relate this to their chemical structure. The third category of this project focused on the recovery of a light crude oil from West Texas (McElroy Field) from a carbonate rock (limestone outcrop). For this effort, the first item was to establish a suite of surfactants that would be compatible with the McElroy Field brine. Those were examined further for their ability to recover oil by imbibition. Results demonstrate several types of promising candidates, and that within a given series of nonionic surfactants the oil recovery appears to be related to the HLB of each surfactant. For the McElroy brine and crude oil system, higher HLB (more water soluble) surfactants perform better than in earlier imbibition tests performed with the model oil and a fresh water or low salinity brine. We speculate that this difference mostly is because a more water soluble surfactant is required to be compatible with higher salinity of the McElroy brine (over 3 wt% salt).«xa0less

Using Ionic Liquids in Selective Hydrocarbon Conversion Processes

This is the Final Report of the five-year project Using Ionic Liquids in Selective Hydrocarbon Conversion Processes (DE-FC36-04GO14276, July 1, 2004- June 30, 2009), in which we present our major accomplishments with detailed descriptions of our experimental and theoretical efforts. Upon the successful conduction of this project, we have followed our proposed breakdown work structure completing most of the technical tasks. Finally, we have developed and demonstrated several optimized homogenously catalytic methane conversion systems involving applications of novel ionic liquids, which present much more superior performance than the Catalytica system (the best-to-date system) in terms of three times higher reaction rates and longer catalysts lifetime and much stronger resistance to water deactivation. We have developed in-depth mechanistic understandings on the complicated chemistry involved in homogenously catalytic methane oxidation as well as developed the unique yet effective experimental protocols (reactors, analytical tools and screening methodologies) for achieving a highly efficient yet economically feasible and environmentally friendly catalytic methane conversion system. The most important findings have been published, patented as well as reported to DOE in this Final Report and our 20 Quarterly Reports.

DEVELOPMENT OF ON-LINE INSTRUMENTATION AND TECHNIQUES TO DETECT AND MEASURE PARTICULATES

In this quarter, we have started the data collection process of the first field deployable multi-wavelength PM measurement system. This system is now operating in real world on PM emissions from a turbine power generator v.s. known PM standard for the system that we designed and tested in the lab. We proved that we could repeatedly collect same scattering signal under same engine load conditions. We further improved the signal to noise ratio of the system, by shortening the exposure time below 1,500 nanosecond and increasing the peak power. Here, we give detailed description on our investigation of the mechanisms in improving precision of pulsed laser timing.

SCREENING METHODS FOR SELECTION OF SURFACTANT FORMULATIONS FOR IOR FROM FRACTURED CARBONATE RESERVOIRS

This topical report presents details of the laboratory work performed to complete Task 1 of this project; developing rapid screening methods to assess surfactant performance for IOR (Improved Oil Recovery) from fractured carbonate reservoirs. The desired outcome is to identify surfactant formulations that increase the rate and amount of aqueous phase imbibition into oil-rich, oil-wet carbonate reservoir rock. Changing the wettability from oil-wet to water-wet is one key to enhancing this water-phase imbibition process that in turn recovers additional oil from the matrix portion of a carbonate reservoir. The common laboratory test to evaluate candidate surfactant formulations is to measure directly the aqueous imbibition rate and oil recovery from small outcrop or reservoir cores, but this procedure typically requires several weeks. Two methods are presented here for the rapid screening of candidate surfactant formulations for their potential IOR performance in carbonate reservoirs. One promising surfactant screening protocol is based on the ability of a surfactant solution to remove aged crude oil that coats a clear calcite crystal (Iceland Spar). Good surfactant candidate solutions remove the most oil the quickest from the chips, plus change the apparent contact angle of the remaining oil droplets on the surface that thereby indicate increasedmorexa0» water-wetting. The other fast surfactant screening method is based on the flotation behavior of powdered calcite in water. In this test protocol, first the calcite power is pre-treated to make the surface oil-wet. The next step is to add the pre-treated powder to a test tube and add a candidate aqueous surfactant formulation; the greater the percentage of the calcite that now sinks to the bottom rather than floats, the more effective the surfactant is in changing the solids to become now preferentially water-wet. Results from the screening test generally are consistent with surfactant performance reported in the literature.«xa0less

Chapter 20 – Atmospheric CO2 Monitoring Systems

Monitoring for atmospheric CO 2 concentrations may be an integral part of any subsurface storage project. Several CO 2 measurement methods may be used to meet the monitoring objectives of assuring there are no large leaks at the surface that might pose a health risk and verifying that the injected CO 2 remains trapped below the Earths surface. Options include remote sensing from satellites or aircraft, open path instruments that can sample over significant distances, and a network of conventional fixed-point detectors. NASA indicates satellite surveys might be useful for a “global” view of CO 2 . Aircraft surveys may be a fast means to collect data near ground level, but this is only practical in an infrequent basis. Instruments located near ground level that are based on open path sampling may offer the most efficient means to monitor long term over a large surface area. They could have the capability to detect increases of just a few percent of CO 2 above normal background, over a sample path of tens of meters, and continuously with unattended operation. Many different commercial fixed-point units based on infrared (IR) spectroscopy are available. These detectors may be better suited to monitor sensitive, high-risk points of leakage rather than be deployed in a network to monitor large surface areas.