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Collaborating Authors
Results
Phase Behavior and Minimum Miscibility Pressure of Confined Fluids in Organic Nanopores
Song, Yilei (China University of Petroleum, Beijing) | Song, Zhaojie (China University of Petroleum, Beijing) | Liu, Yueliang (China University of Petroleum, East China) | Guo, Jia (China University of Petroleum, Beijing) | Bai, Baojun (Missouri University of Science and Technology) | Hou, Jirui (China University of Petroleum, Beijing) | Bai, Mingxing (Northeast Petroleum University) | Song, Kaoping (China University of Petroleum, Beijing)
Abstract Phase equilibrium of shale fluid is highly disturbed due to liquid adsorption and capillary pressure in densely-developed organic nanopores. And the miscibility phenomenon between gas and oil is also changed during gas injection for enhanced oil recovery (EOR). Therefore, it is imperative to develop a general framework of theoretical models and algorithm to investigate the effect of pore proximity on phase behavior and miscibility of confined fluids in shale formations. In this study, first, an improved vapor/liquid equilibrium (VLE) calculation model is presented to calculate the phase behavior of confined fluids based on our modified Peng-Robinson equation of state (A-PR-EOS) which can reflect the effect of adsorption. The capillary pressure across the interface and the critical property shift of pure component are also taken into account. An improved Young-Laplace equation is utilized to simulate capillarity and the shifted critical properties can be obtained using the A-PR-EOS. Then, a prediction process for the phase behavior of a quaternary mixture (CO2, CH4, n-C4H10, n-C10H22) is performed, and the results are compared against the experimental data from previous literature, yielding an average error of 1.29%. Results indicate that the presence of nanopore confinement could decrease the density difference between the liquid and vapor phase of the quaternary mixture, and thus induce the reduction of interfacial tension (IFT). As pore size becomes smaller, the IFT decreases rapidly, especially when the pore radius (Rp) is less than 20 nm. Furthermore, the vanishing interfacial tension (VIT) algorithm and the modified VLE procedure are applied to determine the minimum miscibility pressure (MMP) of Bakken shale oil with CO2. The MMP is reduced from 20.2 MPa at 50 nm pores to 17.5 MPa at 20 nm pores. Hence, the reduction of pore size leads to a decrease in MMP, i.e. the CO2 and the reservoir fluid could reach miscibility at a lower pressure, which is beneficial for CO2-EOR. The proposed model could provide a consistent description of fluid phase behavior over the whole range of pore sizes in the Bakken, and could be applied to guide the development of shale hydrocarbon reservoirs, such as reserves and production estimates.
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- North America > United States > South Dakota > Williston Basin > Bakken Shale Formation (0.99)
- North America > United States > North Dakota > Williston Basin > Bakken Shale Formation > Middle Bakken Shale Formation (0.99)
- (2 more...)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
- Reservoir Description and Dynamics > Fluid Characterization > Phase behavior and PVT measurements (1.00)
- Reservoir Description and Dynamics > Fluid Characterization > Fluid modeling, equations of state (1.00)
Mechanistic Study for the Applicability of CO2-EOR in Unconventional Liquids Rich Reservoirs
Alfarge, Dheiaa (Iraqi Ministry of Oil, Missouri University of Science and Technology) | Wei, Mingzhen (Missouri University of Science and Technology) | Bai, Baojun (Missouri University of Science and Technology)
Abstract In shale oil reservoirs, Improved Oil Recovery (IOR) methods are relatively considered as new concepts compared with in conventional oil reservoirs. Different IOR techniques have been investigated by using lab experiments, numerical simulation studies, and limited pilot tests. Unconventional IOR methods include injecting CO2, surfactant, natural gas, and water. However, CO2 injection is the most investigated option due to different reasons. CO2 has lower miscibility pressure with shale oils, and has special properties in its supercritical conditions, and CO2 injection also solves greenhouse problems. In this paper, numerical simulation methods of compositional models were incorporated with LS-LR-DK (logarithmically spaced, locally refined, and dual permeability) reservoir models and Local Grids Refinement (LGR) of hydraulic fractures conditions to investigate the feasibility of CO2 injection in shale oil reservoirs. Different mechanisms for CO2 interactions with organic surface, shale brine, and shale oil were implemented in different scenarios of numerical models. Molecular diffusion mechanisms, adsorption effects, and aqueous solubility effects were simulated in this study. In addition, linear elastic models and stress-dependent correlations were used to consider geomechanics coupling effects on production and injection processes of CO2-EOR in shale oil reservoirs. Some of the results for this simulation study were validated by matching the performance of some CO2 fieldsโ pilots performed in Bakken formation, in North Dakota and Montana portions. This study extremely found that some of the CO2-EOR pilot tests have a match with the typical simulated diagnostic plots which have CO2 molecular-diffusion rate that is significantly low. Furthermore, this research indicated that CO2 molecular diffusion mechanism has a clearly positive effect on CO2-EOR in huff-n-puff protocol; however, this mechanism has a relatively negative effect on continuous flooding mode of CO2-EOR. Both of dissolution and adsorption mechanisms have a negative effect on CO2 performance in terms of enhancing oil recovery in unconventional formations. Geomechanics coupling has a clear effect on CO2-EOR performance, and different geomechanics models have a different validity in these shale plays. Stress dependent correlations give the best match with CO2-EOR pilots in Bakken formation while linear elastic models would give the best match in Eagle Ford formation. This study explains the effects of different nano and macro mechanisms on the performance of CO2-EOR in unconventional reservoirs since these plays are much complex and very different from conventional formations. Also, general guidelines have been provided in this study to enhance success of CO2-EOR in these types of reservoirs.
- North America > United States > Montana (1.00)
- North America > Canada (1.00)
- North America > United States > North Dakota > Mountrail County (0.28)
- Europe > United Kingdom > North Sea > Central North Sea (0.24)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (1.00)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Maverick Basin > Eagle Ford Shale Formation (0.99)
- (6 more...)
Abstract Carbon dioxide (CO2) flooding is a mature technology in oil industry, which finds broad attention in oil production during tertiary oil recovery (EOR). After five decade's developments, there are many successful reports for CO2 miscible flooding. However, operators recognized that achieving miscible phase is one of big challenge in fields with extremely high minimum miscible pressure (MMP) after considering the safety and economics. Compared with CO2 miscible flooding, immiscible CO2 flooding demonstrates the great potentials under varying reservoir/fluid conditions. A comprehensive and high-quality data set for CO2 immiscible flooding are built by collecting various data from books, DOE reports, AAPG database, oil and gas biennially EOR survey, field reports and SPE publications. Important reservoir/fluid information, operational parameters and project performance evaluations are included, which provides the basis for comprehensive data analysis. Combination plot of boxplot and histogram are generated, where boxplots are used to detect the special cases and to summarize the ranges of each parameter; histograms display the distribution of each parameter and to identify the best suitable ranges for propose guidelines. Results show that CO2 immiscible flooding could recover additional 4.7 to 12.5% of oil with average injection efficiency of 10.07 Mscf/stb; CO2 immiscible technique can be implemented in light/medium/heavy oil reservoirs with a wide range of net thickness (5.2 - 300 ft); yet in heavy oil specifically reservoir (oil gravity <25 ยฐAPI) with thin layer (net thickness< 50 ft) is better.
- Asia > China (0.95)
- Europe (0.68)
- North America > United States > Texas (0.46)
- (2 more...)
- South America > Brazil > Bahia > Tucano Basin > Buracica Field (0.99)
- North America > United States > Texas > Permian Basin > Delaware Basin > Yates Field > Whitehorse Group > Word Group > San Andreas Formation (0.99)
- North America > United States > Texas > Permian Basin > Delaware Basin > Yates Field > Whitehorse Group > Grayburg Formation > San Andreas Formation (0.99)
- (13 more...)
Integrated Investigation of CO2-EOR Mechanisms in Huff-n-Puff Operations Based on History Matching Results
Alfarge, Dheiaa (Iraqi Ministry of Oil, Missouri University of Science and Technology) | Wei, Mingzhen (Missouri University of Science and Technology) | Bai, Baojun (Missouri University of Science and Technology)
Abstract Improved Oil Recovery (IOR) techniques in Unconventional Liquids Rich Reservoirs (ULR) are still a new concept because there is no commercial project for any IOR technique so far. Carbon dioxide (CO2) based EOR technique has been effectively applied to improve oil recovery in the tight formations of conventional reservoirs. Extending this approach to unconventional formations has been extensively investigated over the last decade because CO2 has unique properties which make it the first option of EOR methods to be tried. However, the applications and mechanisms for CO2-EOR in unconventional reservoirs would not necessarily be the same as in conventional reservoirs due to the complex and poor-quality properties of these plays. Since the first CO2-EOR huff-n-puff project was conducted in conventional reservoirs in Trinidad and Tobago in 1984, more than 130 additional projects have been put in operation around the world, mainly located in USA, Turkey, and Trinidad and Tobago. In this study, we combined Decline Curve Analysis (DCA) for the production data of these projects with numerical simulation methods to produce one typical graph accounts for the main mechanisms controlling CO2-EOR performance in conventional reservoirs. On the other hand, we have couple of CO2-EOR huff-n-puff pilot tests conducted in Bakken formation between 2008 and 2016. Two engineering-reversed approaches have been integrated to produce a unique type curve for the performance of CO2-EOR huff-n-puff process in shale oil reservoirs. Firstly, a numerical simulation study was conducted to upscale the reported experimental-studies outcomes to the field conditions. As a result, different forward diagnostic plots have been generated from different combinations for CO2 physical mechanisms with different shale-reservoirs conditions. Secondly, different backward diagnostic plots have been produced from the history match with CO2 performances in fieldsโ pilots performed in some portions of Bakken formation located in North Dakota and Montana. Finally, fitting the backward with the forward diagnostic plots was used to produce another unique type curve to represent CO2-EOR performance in shale oil reservoirs. This study found that the delayed response in the incremental oil production resulted from CO2 injection in shale reservoirs is mainly function of CO2 molecular diffusion mechanism. On the other hand, the CO2 diffusion mechanism has approximately no effect on CO2-EOR performance in conventional reservoirs which have a quick response to CO2 injection. This finding is very well consistent with the experimental reports regarding the role of diffusion in conventional cores versus shale cores. In addition, this study found that kinetics of oil recovery process in productive areas and CO2-diffusivity level are the keys to perform successful CO2-EOR project in shale formations. This paper provides a thorough idea about how CO2-EOR performance is different in the field scale of conventional reservoirs versus shale formations.
- North America > United States > Montana (1.00)
- North America > Canada (1.00)
- North America > United States > North Dakota > Mountrail County (0.28)
- Europe > United Kingdom > North Sea > Central North Sea (0.24)
- North America > United States > South Dakota > Williston Basin > Bakken Shale Formation (0.99)
- North America > United States > North Dakota > Williston Basin > Bakken Shale Formation > Middle Bakken Shale Formation (0.99)
- North America > United States > North Dakota > Sanish Field > Bakken Shale Formation (0.99)
- (2 more...)
Survey and Data Analysis of the Pilot and Field Polymer Flooding Projects in China
Zhang, Yandong (Missouri University of Science and Technology) | Wei, Mingzhen (Missouri University of Science and Technology) | Bai, Baojun (Missouri University of Science and Technology) | Yang, Hongbin (China University of Petroleum) | Kang, Wanli (China University of Petroleum)
Abstract Enhanced oil recovery (EOR) processes are regarded as important methods to recover remaining oil after primary and secondary recovery. It is important to select the most appropriate EOR process among the possible techniques for a candidate reservoir. Therefore, EOR screening criteria have been constructed using available EOR data sets and serve as the first step to compare the suitability of each EOR method for a particular reservoir. Most screening criteria for polymer flooding are based on data sets from EOR surveys published biannually by the Oil & Gas Journal. These surveys missed significant polymer flooding parameters such as formation water salinity and hardness, polymer types and molecular weight, polymer concentration, reservoir heterogeneity, and so on. All of these topics are covered in this paper with data from relevant literature and records provided by oil companies in China. Polymer flooding has been widely applied in China for over 20 years and a large number of pilot and field projects have been conducted. These projects include important information to quantify the development of polymer flooding as an EOR method. Nevertheless, most of them have been published in Chinese, and are not accessible to the global research community due to the language barrier. This paper represents an effort to collect all relevant information of polymer flooding from available Chinese publications and reports from all of the major oil companies in China. The primary objectives of this survey is to reveal EOR advances, to trace the development of the polymer flooding EOR methodology in China, and to benefit EOR worldwide. This project collected information on 55 polymer flooding projects after reviewing nearly 200 publications in Chinese, including 31 pilot projects and 24 field projects from 1991 to 2014. A data set was constructed by collecting all relevant information for polymer flooding. Statistical analyses and graphical methods were used to analyze the whole data set. Box plots combined with violin plots were used to show the distribution and the range of each parameter. By defining and calculating lower and upper limits in box plots, special projects were identified and explained. Scatter plots, which show multiple parameters in one plot, were used to identify significant relationships among different parameters, especially for dependent parameters. This method overcomes some disadvantages of the range method, which is traditionally used for EOR screening. For example, using polymers with high concentration in low salinity reservoirs can lead to higher incremental oil recovery than in high salinity ones, and lower permeability usually correlates with the use of polymers with lower molecular weight. However, the traditional range method cannot show this relationship. Finally, comprehensive screening criteria for polymer flooding were updated based on information revealed in the field application projects.
- Asia > China > Shandong Province (0.46)
- Asia > China > Henan Province (0.46)
- Asia > China > Heilongjiang Province (0.31)
- Asia > China > Xiaermen Field (0.99)
- Asia > China > Tianjin > Bohai Basin > Huanghua Basin > Dagang Field (0.99)
- Asia > China > Shuanghe Field (0.99)
- (13 more...)
Comprehensive Guidelines for the Application of In-Situ Polymer Gels for Injection Well Conformance Improvement Based on Field Projects
Aldhaheri, Munqith N. (Missan Oil Company, Missouri University of Science and Technology) | Wei, Mingzhen (Missouri University of Science and Technology) | Bai, Baojun (Missouri University of Science and Technology)
Abstract Polymer gels are increasingly applied to improve sweep efficiency of different IOR/EOR recovery processes. Three in-situ polymer gel systems including bulk gels, colloidal dispersion gels, and weak gels are often used to mitigate water production caused by reservoir heterogeneity and unfavorable mobility ratio of oil and injected fluids. Selecting the most appropriate gel system is a key component for a successful conformance improvement treatment. Screening criteria in terms of reservoir and fluid characteristics have been widely used to identify potential technologies for a specific reservoir. Despite the large number of polymer gel projects, only five, limited-parameters, single-agent criteria or surveys have been sporadically accomplished that suffer from many deficiencies and drawbacks. This paper presents the first complete applicability guidelines for gel technologies based on their field implementations in injection wells from 1978 to 2015. The data set includes 111 cases histories compiled mainly from SPE papers and U.S. Department of Energy reports. We extracted missing data from some public EOR databases and detected potential outliers by two approaches to ensure data quality. Finally, for each parameter, we evaluated project and treatment frequency distributions and applicability ranges based on successful projects. Extensive comparisons of the developed applicability criteria with the previous surveillance studies are provided and differences are discussed in details as well. In addition to the parameters that are considered for other EOR technologies, we identified that the applicability evaluations of polymer gels should incorporate the parameters that depict roots and characteristics of conformance issues. The present applicability criteria comprise 16 quantitative parameters including permeability variation, mobility ratio, and three production-related aspects. Application guidelines were established for organically crosslinked bulk gels for the first time, and many experts' opinions in the previous criteria were replaced by detailed property evaluations. In addition, we identified that the applicability criteria of some parameters are considerably influenced by lithology and formation types, and thus, their data were analyzed according to these characteristics. Besides their comprehensiveness of all necessary screening parameters, the novelty of the new criteria lies in their ability to self-check the established validity limits for the screening parameters which resulted from the inclusion and simultaneous evaluation of the project and treatment frequencies.
- South America (1.00)
- North America > United States > Texas (0.93)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.54)
- South America > Venezuela > Lake Maracaibo > Maracaibo Basin > Lagomar Field (0.99)
- South America > Colombia > Huila Department > Neiva Basin > Balcon Field (0.99)
- South America > Colombia > Huila Department > Magdalena Basin > Tello Field (0.99)
- (16 more...)