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Almeida da Costa, Alana (Universidade Federal da Bahia) | Jaeger, Philip (Eurotechnica GmbH) | Santos, Joao (Láctea Científica) | Soares, João (University of Alberta) | Trivedi, Japan (University of Alberta) | Embiruçu, Marcelo (Universidade Federal da Bahia) | Meyberg, Gloria (Universidade Federal da Bahia)
Low salinity waterflooding and CO2 injection are enhanced oil recovery (EOR) methods that are currently growing at a substantial rate worldwide. Linking these two EOR methods appears to be a promising approach in mature fields and for the exploration of post- and pre-salt basins in Brazil. Moreover, the latter reservoirs already have high CO2 content in the gas phase. Interfacial phenomena between fluids and rock in low salinity brine/CO2 environment still remain unclear, particularly the wettability behavior induced by the pH of the medium. In this study, coreflooding experiments, zeta potential, contact angle, interfacial tension (IFT), and pH measurements at ambient and reservoir conditions were performed to investigate the influence of the rock composition and brine/CO2 mixtures at different pH values for low salinity water-CO2 EOR (LSW-CO2 EOR) applications in Brazilian reservoirs. Brazilian light crude oil, pure CO2, and different brine solutions were used to represent the fluids in actual oil reservoirs. The experiments were carried out on Botucatu sandstone samples, with mineralogy determined by energy dispersive X-ray analysis. Coreflooding experiments were conducted by injection of 10 pore volumes of high salinity water followed by low salinity water. Contact angles, IFT and pH measurements at atmospheric and elevated pressures were performed in a high-pressure view cell (
The high CO2 content of Brazil’s pre-salt fields, which may reach values from 20% to 44% molar, presents both a challenge as well as an opportunity. CO2 stripped from the produced gas cannot be released into the atmosphere due to environmental restrictions. Therefore, the whole amount of CO2 produced should be continuously reinjected into the reservoir. This work investigates the effect of CO2 content on the low salinity water alternating CO2 injection technique (CO2LSWAG) using a commercial compositional reservoir simulator. In these field-scale simulations, CO2 is stripped from the produced gas and reinjected into the reservoir. Primary oil recovery methods such as CO2 flooding and LSW flooding are also simulated. Chemical reactions between CO2 and the minerals present in the reservoir are modeled. Wettability change is assumed to be the main mechanism for improved oil recovery due to low salinity water injection. Compositional simulations of CO2 injection usually assume a constant injected gas rate. In this case, CO2 is supposed to come from an external source. In many petroleum reservoirs this assumption is true. Three factors are assessed in the present work. The first one is the natural reservoir pressure, which is the main driving force in primary production. The second factor is the amount of CO2 available for injection. The third one is the wettability change promoted by the reaction involving CO2. It is shown that in primary production, higher CO2 content leads to quicker depletion of the natural energy of the reservoir, leading to lower oil recovery. Nevertheless, higher CO2 content also means that more gas is available for reinjection, potentially leading to increased oil production. Finally, as CO2 reacts with minerals it promotes a change in wettability from an oil-wet to a water-wet state. It is shown that the CO2 content is an important variable to be assessed in a high CO2 content reservoir. Optimal injection practices must take these three aspects into consideration.
Almeida, Alana (Universidade Federal da Bahia, University of Alberta) | Patel, Rajan (University of Alberta) | Arambula, Carolina (University of Alberta) | Trivedi, Japan (University of Alberta) | Soares, João (University of Alberta) | Costa, Gloria (Universidade Federal da Bahia) | Embiruçu, Marcelo (Universidade Federal da Bahia)
Several researchers have demonstrated in laboratory experiments and field applications that reducing the concentration of salts and the content of multivalent cations in the injection water may increase oil recovery. This study evaluates the performance of low salinity water injection (LSWI) in oil recovery using a crude oil and synthetic formation water of a sandstone reservoir in northeast Brazil. Two Botucatu sandstone core samples of 6 in of length and 2 in of diameter were used for the coreflooding experiments. The fluids used included a light crude oil sample, and synthetic formation water (SFW) produced from the four main salts of the original formation water (NaCl, KCl, CaCl2, and MgCl2). In Core 1, two injections were carried out at an average reservoir temperature of 60 °C, one using SFW with 200,000 mg/l as secondary recovery mode, and one using SFW diluted 40 times (40xd_SFW) resulting in a low salinity water of 5,000 mg/l as tertiary recovery mode. In Core 2, 40xd_SFW was injected at the same temperature to compare the high and low salinity water effects in the secondary mode. Moreover, zeta (ζ) potential measurements on Botucatu sandstone powder were performed in 6 dilutions of the SFW and deionized water. The experimental results demonstrated an increase in oil recovery and pH when 40xd_SFW was injected in secondary and tertiary modes. The effluent ionic concentration from Core 1 showed the reduction of Ca2+ during HSWI, indicating its adsorption on the rock surface. Most remarkably, Ca2+ concentration increases and the Na+ concentration decreases in the effluent samples in the first LSWI pore volume injected, which suggested ionic exchange of calcium for sodium on the rock surface. Furthermore, Fe2+/Fe3+ and traces of Al3+ were observed in the effluent demonstrating the occurrence of fine migration in SFW and 40xd_SFW. The magnitude of negative ζ potential on Botucatu sandstone increases as the salinity of the brine solutions decreases. Based on that experimental study, it is noticed that a set of LSWI mechanisms occurr simultaneously in Botucatu sandstone, and oil and brine samples from Recôncavo Basin, indicating a potential of application for LSWI in similar Brazilian oil reservoirs.
dos Santos, C. M. (Universidade Federal da Bahia) | Regnier, P. (Universidade Federal da Bahia) | Pepe, I. (Universidade Federal da Bahia) | Alfonzo, J. (Universidade Federal da Bahia) | Silva, L. (Universidade Federal da Bahia) | Vidal, V. (Universidade Federal da Bahia) | Júnior, J. (Universidade Federal da Bahia)
This project aims to elaborate, develop and validate a mechatronic platform able to automate the process of acquisition, processing, digitizing and display of analogical electrical signals. In this work, the signals will be supplied by piezoelectric sensors used to measure the three-dimensional ultrasonic wave field produced by ultrasonic transducers in a pipe. Such platform will allow studying the use of ultrasonic field for the cleaning of dirty oil pipelines.
Normally the singular value decomposition (SVD) filtering is applied in the tx (time x distance) domain, exploring the spatial correlation between a set of seismic traces. In this paper we present a single trace decomposition approach based on the SVD method. This approach works on single traces decomposing each seismic trace based on the temporal correlation of the reflected events. We illustrate the method in the prediction and removal of the ground-roll.
Presentation Date: Tuesday, October 18, 2016
Start Time: 8:50:00 AM
Presentation Type: ORAL
Asphaltene precipitation is a challenging and complex problem in all sections of the oil industry including oil production, transportation and processing. Asphaltenes can plug pumps, valves, tubing and flow lines, cause fouling in surface handling facilities and even act as coke precursors and catalyst poisons. For these reasons, the occurrence of asphaltene deposits may result in productivity losses and sometimes even production shutdowns. For many years, much effort has been done on modelling asphaltene precipitation because experimental investigation is a hard task. Thermodynamic models based on Flory-Huggins theory have been used by several oil companies to predict the asphaltene onset conditions due to the depletion or gas injection. However, the main requirement to accomplish a successful calculation of asphaltene precipitation is an accurate solubility parameter. A variety of models to calculate asphaltene precipitation based on the solubility parameter is available in literature but most of them are complex due to inherent assumptions that are built-in. In this work, a new simple and accurate method to calculate the asphaltene solubility parameter is proposed, which requires only SARA (saturate, aromatic, resin, and asphaltene) analysis, the oil composition and the reservoir temperature. Once it is sufficient to know up to C7+ fraction, a much detailed analysis of the oil composition is unnecessary. Soave-Redlich-Kwong (SRK) (
Wax precipitation is one of the most important flow assurance problems that cause a decrease of oil production rates, an increase of energy consumption and failure of facilities. A very simple and accurate model can be used as a fundamental tool to predict and prevent solid precipitation at different conditions. An extension of the Won (1986) model is presented that calculates the Wax Appearance Temperature (WAT) considering the temperature dependence of the solubility parameters of the individual components in the liquid and solid phases as well as the molar volumes of the individual components. In addition to predict WAT, the liquid and the solid composition in equilibrium are estimated without having available the Paraffins, Naphtenes and Aromatics (PNA) analysis. Results are compared for 18 oils from literature data. Regarding the experimental data it is enough to know only the molar fraction and the molecular weight of each component. Even if the oil composition is known only up to C 7 fraction the extension of residue is possible through Pedersen et al. (1989) method. A percentile absolute average deviation of about 2% to 3% for WAT was obtained.
Câmara, R. J. B. (Universidade Federal da Bahia - Programa de Enhenharia Industrial (PEI)) | Carvalho, L. F. J. (Universidade Federal da Bahia) | Câmara, G. A. B. (Câmara Consultoria) | Rocha, P. S. M. V. (Universidade Salvador)
Since the start of production in the pre-salt zone, Brazil became a large oil producer in the global scenario. Reserves certification is one of the most controversial topics in the oil industry. A reliable declaration of the oil reserves is essential to establish an appropriate condition that encourage the private sector, bring stability to society and get the government evolved. There are different manners for a company to certificate its oil reserves in the world; it depends on where the hydrocarbon is being produced. The reserves certification for the concessionaire companies in Brazil is performed by independent consultancy firms that execute certification under the ANP (National Agency of Petroleum, Gas and Biofuels) regulation. The regulation number 47 of September 3 of 2014 states the criteria for reserves certification in the country. This resolution is based on the Petroleum Resources Management System (PRMS), a document drafted by Society of Petroleum Engineers (SPE). Because of this diversity, this paper come up with a mapping of the existing systems for reserves certification in the fifteen largest world oil producers countries and Colombia, that is not a major producer but has a recent and solid regulation for reserves certification. This work is being developed to identify gaps and weakness in the current Brazilian regulatory rules aiming to avoid situations like the OGX company case. This company did not provide the same information to the regulatory agency and to the financial market. The instability in market reports to what happened to Royal Dutch/Shell Group in January 9 of 2004, even it is about a different technical situation. The methodology applied was based on the literature search about the subject and comparative analysis of the data. The research conduced to the main regulatory items in reserve certification for these countries: the existence of specific regulations for reserve certification, the productions limits for certification, the statement of reserves by the operator for the government agency and the recognition of the independent consultancy firms by the government agency. After analyzing the information obtained, it was realized that most of those countries do not have specific regulations for reserves certification. Some of these countries use the PRMS as a guideline and others simply use the numbers of reserves certified as political currency, disregarding any technical guidance. Finally, it was concluded the need for certain information about the numbers presented to the government and the financial market by the oil companies because the current system is shown unstable as evidenced by the research.
The production and operations in oil and gas fields are getting more complex, with more and more demanding restrictions for safety, energy efficiency, environment, which sets new technical challenges for automation and control. On the other hand, modeling and system identification tools and advanced control systems can be an important key to enhance stability and cost effectiveness and support the personnel (operators, engineers, etc.). This article will illustrate some results obtained with the application of modeling and advanced control systems for artificial lift using smart field technologies.
This work proposes a new method of diagnosing the Sucker Rod Pump Systems, by analyzing segments between the points of opening and closing valves identified in the Downhole Dynamometer Cards. An analysis of the shape of the pumping condition classes represented in the Downhole Dynamometer Cards, especially regarding the behavior of segments between the valve opening and closing points is presented. The feasibility of the classification of Downhole Dynamometer Cards by the curvature characteristics of segments is demonstrated. Then, methods of classification of 16 pumping condition classes are presented, 4 by simple statistics and 12 of them extracting curvature characteristics of the segments andusing statistics to implement Mamdani fuzzy inference systems. Tests are developed with classifiers created by the method, and the test results over a library of Dynamometer Cards from real wells, previously classified by human experts, demonstrate the feasibility of the approach and the precision of the classification even without a deeper study to choose the better characteristics and statistics.