Miscible Oil Research Articles

Efficiency of certain miscible oils and chlorpyriphos methyl insecticide against the soft scale insect, Kilifia acuminata Signoret (Homoptera: Coccidae) and their toxicities on rats

The toxicity and efficacy of using three miscible oils; cabl-2, citrole and bio-dux and a chemical insecticide (chlorpyrifos-methyl) were studied against a soft scale insect, Kilifia acuminata (Signoret) infesting mango trees. The sub-chronic toxicity of tested chemicals on white albino rats was also studied. Considering the general mean number of K. acuminata stages after 3 months post spraying, chlorpyrifos methyl and capl-2 were the most efficient compounds followed by citrol and bio-dux in descending order. Chlorpyrifos-methyl was the most effective treatment for all months after spraying, the mean reduction percentage being 94.10, 91.63 and 92.00% while it gave the highest toxic effect after three months; 90.27, 87.84 and 89.73% reduction in infestation on pre-adult, adult and gravid female stages, respectively. Results also indicate that the general mean percent reduction in K. acuminata infestation were 82.62, 86.67, 78.87 and 89.28% in treated trees by citrole, cabl-2, bio-dux and chlorpyrifos-methyl, respectively. Citrole, bio-dux, cabl-2 and chlorpyrifos-methyl caused significant increase in WBCs counts, ALT and AST activities of treated rats after 15 and 30 days from treatment comparison with control. Changes occurring in the creatinine concentration showed a significant increase in rats treated with the tested chemicals 30 days from treatment, except in the case of bio-dux oil, while there were no significant changes after 15 days in rats treated with tested oils. On the contrary, tested chemicals caused a significant decrease in RBCs count and hemogobin values after 15 and 30 days form treatment, except in rats treated with bio-dux oil. Hemoglobin content showed no significant changes over the same periods.

Oil Distribution in iPP/EPDM Thermoplastic Vulcanizates

Abstract Scanning Probe Microscopy (SPM) was used to determine the volume fraction of oil-swollen particulate rubber and oil-swollen plastic in thermoplastic vulcanizates (TPVs) produced from iPP and EPDM rubber. Sample preparation and SPM imaging conditions allowed the ratio of the rubber and plastic area imaged for a TPV sample to be equated to the phase volume ratio. The hydrosilylation cured TPVs contained no filler or inorganic components (other than about 1 ppm of platinum catalyst, based on dry rubber) that would decrease the accuracy of the SPM analysis. The accuracy of the SPM method used for TPV phase volume determination was established by analysis of an oil-free TPV of known composition. The densities of the individual TPV components (rubber, oil, crystalline and amorphous plastic phase), which were assumed to be additive in the composite, were used to calculate the oil distribution between the TPV rubber and plastic phase, since the volumes of the individual components (the extent of plastic crystallinity was measured by differential scanning calorimetry) were known. Thus, the amount of oil in the oil-swollen TPV rubber and plastic phase could be quantified. This information, coupled with the Tg of the oil-swollen amorphous plastic phase, indicated that a substantial amount of oil was present as a separate oil phase that is surrounded by the oil-swollen amorphous plastic phase. To date, it has been assumed that the oil in a TPV partitions between the rubber and amorphous plastic phase, with the plastic crystallites being oil free. This work is the first demonstration of the presence of a separate oil phase in TPVs, and the first accurate determination of the oil content in the oil-swollen rubber, miscible oil in the oil-swollen amorphous plastic, and the free oil in TPVs.

Phase Behaviour and Compositional Changes Associated With Residual Oxygen in a Miscible CO/Light Oil Reservoir

Abstract Concern about the effects of global greenhouse gases has made people aware of the need to reduce the atmospheric concentration of industrial waste gas. Alberta, as the centre of Canada's petroleum industry, is strongly impacted by the politics of greenhouse gases. One way Alberta can achieve the goals of the Kyoto Protocol is to capture CO2 from stack gases and to inject it into oil reservoirs to enhance recovery while sequestering at least a portion of the CO2. This paper will concentrate on oil from the Swan Hills Formation reservoir operated by Devon Oil Corporation. The phase behaviour of different concentrations of CO2/O2 mixtures injected into the Swan Hills reservoir was investigated. Two PVT (Pressure-Volume-Temperature) apparatus were used to visually observe phases and to determine bubble points and swelling of the oil rich phase. The PVT measurements were performed to develop a basic understanding of the phase behaviour for the CO2 / O2 /oil system. The composition of oxidized oil was predicted using a previously developed low temperature oxidation model coupled with phase equilibrium calculations. Introduction Carbon dioxide flooding is a well established enhanced oil recovery process in regions where CO2 is available. Canada has been slow to implement CO2 floods due to the lack of natural sources. However, the public's concern with greenhouse gas emissions and Canada's support for the Kyoto Protocol provide sufficient environmental incentives to allow for the application of CO2 floodingas a combined EOR/sequestration process. Capturing the CO2 from stack gas is an expensive process and the actual cost will depend on the purity of the CO2 stream that is required. Oxygen is an important factor as its impurity can modify the native oil properties through low temperature oxidation reactions, promotion of corrosion in the injection and production piping and alter the phase behaviour of the reservoir fluids. The study described in this paper will examine how oxygen is consumed in the reservoir, and it will concentrate on the impact of oxidation reactions with regard to the composition and emulsification characteristics of the oil. Lee(1) studied the phase behaviour and displacement efficiency of a carbon dioxide-hydrocarbon system which consisted of various mixtures of n-pentane/n-hexane. The results demonstrated that multiple phase behaviour involving two liquids with and without a vapour phase occurred during carbon dioxide injection in low temperature reservoirs. A number of studies on the effectiveness of carbon dioxide displacement under miscible and immiscible conditions have been reported by Wilburn et al.(2), Dyer et al.(3), Srivastava and Huang(4, 5) and Srivastava et.al.(6). The results showed that CO2 /oil miscibility could be developed and that the swelling behaviour depended on the chemical composition of the oil. Wilburn et al.(2) also found that miscibility is strongly dependent on the volatility or boiling point distribution of the oil. Dyer et al.(3) investigated the phase behaviour of typical Saskatchewan heavy oils with carbon dioxide. Their study was divided into two categories: stock tank oil and reservoir oil, which were mixed with CO2 in different ratios. Parameters studied included viscosity, density, swelling factor and gas-oil ratio (GOR).

Phase equilibrium engineering of the extraction of oils from seeds using carbon dioxide + propane solvent mixtures

The use of propane + carbon dioxide mixtures can offer special properties regarding solvent power, selectivity and safety. In the present work, we studied the phase equilibrium engineering for the extraction of fixed oils from ground seeds. The selection of operating conditions is based on a ternary diagram that limits the region of complete miscibility and non-flammable mixtures. On the basis of the selected conditions, we carried out extraction experiments of soy oil, sunflower oil and hiprose oil from ground seeds. The extraction studies covered a range of propane + CO 2 solvent mixtures, at conditions of complete and/or partial miscibility with the oil. We observed that the oil extraction rate decreases as the CO 2 concentration in the solvent mixture increases, even in the region of complete solvent + oil miscibility. This behavior is explained on the basis of the effect of the thermodynamic properties of the oil + solvent solution on the mass transfer rate.

A new mechanistic Parachor model to predict dynamic interfacial tension and miscibility in multicomponent hydrocarbon systems

Widely used traditional Parachor model fails to provide reliable interfacial tension predictions in multicomponent hydrocarbon systems due to the inability of this model to account for mass transfer effects between the fluid phases. In this paper, we therefore proposed a new mass transfer enhanced mechanistic Parachor model to predict interfacial tension and to identify the governing mass transfer mechanism responsible for attaining the thermodynamic fluid phase equilibria in multicomponent hydrocarbon systems. The proposed model has been evaluated against experimental data for two gas–oil systems of Rainbow Keg River and Terra Nova reservoirs. The results from the proposed model indicated good IFT predictions and that the vaporization of light hydrocarbon components from crude oil to gas phase is the governing mass transfer mechanism for the attainment of fluid phase equilibria in both the gas–oil systems used. A multiple linear regression model has also been developed for a priori prediction of exponent in the mechanistic model by using only the reservoir fluid compositions, without the need for experimental measurements. The dynamic nature of interfacial tensions observed in the experiments justifies the use of diffusivities in the mechanistic model, thus enabling the proposed model predictions to determine dynamic gas–oil miscibility conditions in multicomponent hydrocarbon systems.

Experimental investigation of miscible and immiscible Water-Alternating-Gas (WAG) process performance

Gas injection is the second largest enhanced oil recovery process, next only to thermal processes used in heavy oil fields. To increase the extent of the reservoir contacted by the injected gas, the gas is generally injected intermittently with water. This mode of injection, called water-alternating-gas (WAG), is being widely practiced in the oil fields. This experimental study is aimed at evaluating the performance of the WAG process as a function of gas–oil miscibility and brine composition. This performance evaluation has been carried out by comparing oil recoveries from WAG injection with those from continuous gas injection (CGI). Miscible floods were conducted at 17.24 MPa (2500 psi) and immiscible floods at 3.45 MPa (500 psi) using rock–fluids systems consisting of Berea cores, n-Decane and two different brines, namely the commonly used 5% NaCl solution and another being the multi-component reservoir brine from the Yates field in West Texas. The coreflood protocol consisted of a series of steps including brine saturation, absolute permeability determination, flooding with oil (drainage) to initial oil saturation, end-point oil permeability determination, flooding with brine (imbibition) to residual oil saturation, end-point water permeability determination, and finally, tertiary gas injection (in both continuous injection and WAG modes) to recover the waterflood residual oil. When oil recovery per unit volume of gas injection was used as a parameter to evaluate the floods, the WAG mode of injection out-performed the CGI. As expected the miscible floods were found to out-perform the immiscible floods. At increased volumes of gas injection, the performance of miscible CGI flood, in spite of the high injection pressure, approached that of the low-pressure immiscible floods. A change in brine composition from 5% NaCl to 0.926% multivalent brine from Yates reservoir showed a slight adverse effect on tertiary gas flood recovery due to increased solubility of CO 2 in the latter. The results of this study suggest that the optimum mode of gas injection is a combination process between CGI and WAG modes of gas injection.

HFC134a/HC600a/HC290 mixture a retrofit for CFC12 systems

The environmental concerns with the impact of refrigerant emissions lead to the importance in identifying a long-term alternative to meet all requirements in respect of system performance and service. Even though HFC134a and HC blend (containing 55.2% HC600a and 44.8% HC290 by weight) have been reported to be substitutes for CFC12, they have their own drawbacks in respect of energy efficiency/flammability/serviceability aspects of the system. In this present work, experimental investigation has been carried out on the performance of an ozone friendly refrigerant mixture (containing HFC134a/HC blend) in two low temperature systems (a 165 l domestic refrigerator and a 400 l deep freezer) and two medium temperature systems [a 165 l vending machine (visi cooler) and a 3.5 kW walk-in cooler]. The oil miscibility of the new mixture with mineral oil was also studied and found to be good. The HFC134a/HC blend mixture that contains 9% HC blend (by weight) has better performance resulting in 10–30% and 5–15% less energy consumption (than CFC12) in medium and low temperature system, respectively.

Synthesis of photodegradable TiO 2/stearate complex and characterization of its Langmuir monolayer at the air/water interface

The water pollution from organic compound has became a serious global problem. The TiO 2 photocatalyst illuminated with UV light can decompose organic compound. Since the specific gravity of TiO 2 particles is larger than water, the photodecomposition of organic compound in the water was difficult. So we synthesized TiO 2/stearate complex for the efficient decomposition of organic compound for the efficient photodegradation of aggregated organic pollutants. The photodegradable TiO 2/stearate complex has been prepared with sodium stearate. This was identified with FT-IR, water contact angle, TGA and TEM images. This complex was studied as Langmuir monolayer at the air/water interface on the miscibility and photodegradability of organic crude oil which was exposed at the sea water with pressure–area isotherm, Brewster angle microscope (BAM) and surface tensiometer.

Absorption Properties of Coatings: A Selected Overview of Absorption Criteria Derived from Recent Pore Network Modelling

Absorption of fluids into porous media controls the printability characteristics of coated papers in respect to ink setting rate and phenomena such as wicking and bleeding. The dynamic of absorption is related to the runnability on printing presses. Pore structure, size distribution, and surface chemistry are the parameters which can be used to design structures for optimal absorption. To achieve a working understanding it has been necessary to develop the theory of absorption to encompass the short timescale fast absorption occurring during wetting of the fluid ink onto the surface of the paper. The phenomena of fluid spread and absorption are studied and shown to depend on the observed pore size distribution rather than porosity alone. This finding calls into question the traditional acceptance of the Lucas–Washburn relationship for such porous networks as the hydraulic absorption radius determined from experimental absorption rate measurements fails to follow the actual measured pore size trend. It is necessary to invoke the concept of a preferred pathway of absorption in which only selected groups within the finest connecting pores or throats of the network in combination with intermediate pore reservoirs contribute maximally to the transmission of fluid through the coating structure as porosity increases. By defining the pore size range involved in this mechanism using an inertial wetting term, found in the short time solution to the Bosanquet equation, it is possible for the first time to identify the connective structures responsible for the important time dependent absorption properties of coatings and their relationship to the ink tackification and/or setting rates for a range of printing ink solvents and diluents, including offset, rotogravure, flexographic, and ink jet inks. Additionally, the differential chromatographic effect of coatings and associated binder systems results in further time dependent offset ink setting phenomena in which miscible ink oils of different natures separate within the coating pores and between the pores and synthetic latex binders. In situ determination of the viscosity and solids content of an offset ink via static ink tack measurements allows the dynamic of ink setting to be studied on real coating systems. Combining these criteria, the necessary steps can be followed to design the coating pigment structures required for optimising existing and future fluid‐based printing technologies.

Influences of Miscible and Immiscible Oils on Flow Characteristics Through Capillary Tube—Validation of Calculation Model

A capillary tube is widely used as an expansion device for small refrigeration cycles. This series of papers discusses the influence of mixing refrigeration oil with the refrigerant on the flow through the capillary tube. In the first report, the mass flow rate and temperature and pressure distributions are examined experimentally when miscible or immiscible oil is mixed with refrigerant. In this study, a theoretical model is developed to estimate the influence of oil on the properties of refrigerant/oil mixture and on the mass flow rate. The theoretical model for the miscible combination is also applicable to the immiscible one, since the immiscible oil mixes homogeneously in the liquid phase in the capillary tube. The mass flow rates in both cases of miscible and immiscible combinations are calculated within an error of ±5% in comparison to measured data. In the immiscible combination, however, the model tends to underestimate the mass flow rate slightly as the oil concentration becomes larger than 0.1.

Moderately high temperature water source heat-pumps using a near-azeotropic refrigerant mixture

A ternary mixture of R124/R142b/R600a, named HTR01, for moderately high temperature heat pumps, was developed. Tests of material compatibility and oil miscibility showed that the mixture could be used with a R22 compressor in an HTR01 heat-pump system. A 2.92 kW moderately high temperature water source heat pump system was set up with HTR01 as the refrigerant to study the system performance with HTR01. Then, a 300 kW moderately high temperature water source heat pump system was built with HTR01 as the refrigerant to test the performance with a geothermal hot water source. The test showed that the condenser outlet water temperature could reach and hold on about 90 °C with a high coefficient of performance.

Streamline-based mathematical model for CO2 miscible flooding

According to the research theory of improved black oil simulator, a practical mathematical model for CO2 miscible flooding was presented. In the model, the miscible process simulation was realized by adjusting oil/gas relative permeability and effective viscosity under the condition of miscible flow. In order to predict the production performance fast, streamline method is employed to solve this model as an alternative to traditional finite difference methods. Based on streamline distribution of steady-state flow through porous media with complex boundary confirmed with the boundary element method (BEM), an explicit total variation diminishing (TVD) method is used to solve the one-dimensional flow problem. At the same time, influences of development scheme, solvent slug size, and injection periods on CO2 drive recovery are discussed. The model has the advantages of less information need, fast calculation, and adaptation to calculate CO2 drive performance of all kinds of patterns in a random shaped porous media with assembly boundary. It can be an effective tool for early stage screening and reservoir dynamic management of the CO2 miscible oil field.

Ozone friendly HFC134a/HC mixture compatible with mineral oil in refrigeration system improves energy efficiency of a walk in cooler

In the event of chlorofluorocarbon (CFC) phase out, identifying a long term alternative to meet all our requirements in respect of system performance and service is an important area for research in the refrigeration and air conditioning (RAC) sector. Even though HFC134a and the HC blend (containing 55.2% HC600a and 44.8% HC290) have been reported to be substitutes for CFC12, they have their own drawbacks in energy efficiency, flammability and serviceability aspects of the system. HFC134a is not miscible with mineral oil, and hence, polyol ester oil is recommended, which is highly hygroscopic in nature. This hygroscopicity demands stringent service practices, which otherwise results in moisture entry into the system. On the other hand, the HC blend has flammability issues, and hence, the charge quantity in systems is limited by safety standards. This work focuses on experimentally studying the performance of an ozone friendly refrigerant mixture (containing HFC134a/HC600a/HC290) in a walk in cooler, operating with an open type compressor with mineral oil as lubricant. To have a realistic comparison of the new mixture performance, tests were conducted with the conventional refrigerant (CFC12) for the system behaviour, such as no load pull down time, motor power, energy consumption, ON and OFF cycle time, temperature distribution along the coil and COP. The performance of the system with the new mixture was studied and compared. The oil miscibility of the new mixture with mineral oil was also studied and found to be good. It is observed that the mixture has better performance, resulting in 28.6% less energy consumption than CFC12. The enhancement in COP was 6–10%.

Determination of gas–oil miscibility conditions by interfacial tension measurements

Processes that inject gases such as carbon dioxide and natural gas have long been and still continue to be used for recovering crude oil from petroleum reservoirs. It is well known that the interfacial tension between the injected gas and the crude oil has a major influence on the efficiency of displacement of oil by gas. When the injected gas becomes miscible with the crude oil, which means that there is no interface between the injected and displaced phases or the interfacial tension between them is zero, the oil is displaced with maximum efficiency, resulting in high recoveries. This paper presents experimental measurements of interfacial tension between crude oil and natural gases (using a computerized drop shape analysis technique) as a function of pressure and gas composition at the temperature of the reservoir from which the crude oil was obtained. The point of zero interfacial tension was then identified from these measurements by extrapolation of data to determine minimum miscibility pressure (MMP) and minimum miscibility composition (MMC). The gas–oil miscibility conditions thus obtained from interfacial tension measurements have been compared with the more conventional techniques using slim-tube tests and rising-bubble apparatus as well as predictive correlations and visual observations. The miscibility pressures obtained from the new VIT technique were 3–5% higher than those from visual observations and agreed well with the slim-tube results as well as with the correlations at enrichment levels greater than 30 mol% C 2+ in the injected gas stream. The rising bubble apparatus yielded significantly higher MMPs. This study demonstrates that the VIT technique is rapid, reproducible, and quantitative, in addition to providing visual evidence of gas–oil miscibility.

OXIDATION CHARACTERISTICS OF SOYBEAN OILS AS WATER PUMP LUBRICANTS

The use of soybean oil as an alternative lubricant is being investigated extensively, but its relatively rapid thermaland oxidative polymerization restricts its usefulness. Measurement of polymerized oil film thickness and film weight, asmethods for quantifying the degree of polymerization, were investigated. The miscibility and polymerization behavior of crudesoybean oil, proprietary commercial biobased drip oil (BDO), soybean methyl esters, glycerol, and water and their mixtureswere investigated. In a separate study, the antioxidant characteristics of Tenox, 2,2,4,5,5Pentamethyl3imidazoline1oxyl (PMIO), ethylenediaminetetraacetic acid (EDTA), and ionic copper in acidic and alcohol media each in 1% (w/w)concentrations and their formulations mixed with soybean oil were investigated. In the first study, measurement ofpolymerized film weight was preferable to measurement of film thickness for quantifying the extent of polymerization. Soybeanmethyl esters showed the least degree of polymerization. In the next study, ionic copper in acidic media showed the highestresistance to polymerization, followed by the mixture of PMIO and Tenox. The treatments that contained EDTA and Tenoxhad antioxidant properties that were superior to that of the BDO. PMIO tended to promote the polymerization process.

Flooded Boiling of Ammonia with Miscible Oil Outside a Horizontal Plain Tube

Pool boiling tests were conducted with plain steel tubing using pure ammonia and a mixture of ammonia and a miscible lubricant. By comparing the results, the effect of miscible lubricant on shell-side boiling heat transfer coefficient of ammonia was quantified. The experiment covered saturation temperature from −23.3° C to 7.2°C (−10° F to 45°F) and heat flux up to 60 kW/m2 [19,000 Btu/(h·ft2)]. Nucleate boiling of ammonia took place outside a plain steel tube of 19.1 mm (0.75 in.) diameter. The tube was heated by liquid flowing inside to simulate a real heat exchange device. A polyalkylene glycol lubricant, miscible with ammonia, was tested at 0%, 1%, 5%, and 10% mass concentrations. The experimental results showed that under a particular saturation temperature and heat flux, the heat transfer coefficient generally first decreased with an increase in oil concentration up to 5%. It was then followed by an insignificant increase in the coefficient with a further increase in oil concentration to 10%. At a low temperature and a high heat flux, the heat transfer coefficient decreased with the lubricant concentration and stayed constant. The effect of miscible lubricant strongly depends on saturation temperature and weakly depends on heat flux. The largest degradation of heat transfer performance due to the miscible lubricant occurs at the present low temperature of −23.3°C where the heat transfer coefficient can be reduced by up to 33%. A general correlation was developed for heat transfer coefficients both with and without lubricant effect.

Simulation of Horizontal Wells to Mitigate Miscible Solvent Gravity Override in the Virginia Hills Margin

Abstract Significant incremental recovery can be obtained when vertical sweep is improved in the mature Phase I Miscible Flood area of the Virginia Hills Field. This study advances our knowledge of the gravity override processes operating in this complex carbonate reservoir. Furthermore it shows that horizontal injection wells improve sweep efficiency thereby alleviating the impact of solvent gravity override. As a result of this simulation, a successful horizontal injection well was drilled, with an actual 18 E3m3 incremental oil recovery to date and a predicted 65 E3m3 total incremental oil. The results of this study suggest redevelopment in mature EOR areas is expected to extend the life of the miscible flood and increase overall recovery. Introduction Miscible recovery in the Virginia Hills Field Hydrocarbon Miscible Flood (HCMF) project is significantly limited by poor vertical sweep of the solvent within individual layers of the reservoir. A vertically continuous interval within the reef margin (30 m thick) was investigated and shown to have a large bypassed tertiaryoil target. This study demonstrated that recovery could be significantly increased through the use of horizontal solvent injection wells. To have confidence in the results of the study it was critical to utilize geological and production history data to address the interwell extent of significant heterogeneities. This required complete integration of geological and engineering staff in all phases of the study. Background Historical The Virginia Hills Beaverhill Lake A Pool was discovered in 1957. The field (Figure 1) produces oil from a Mid-Upper Devonian limestone, stromatoporoid build-up. The field was unitized in 1963 and a waterflood pressure maintenance scheme was implemented. In the late 1980s the patternswere normalized to inverted nine spots and in 1989 a tertiary horizontal hydrocarbon miscible flood project was initiated in the south half of the Pool. The original oil in place (OOIP) for the pool has been calculated at 59.6 E6m3 by the operator. Cumulative oil production to the end of July 1996 was 22.9 E6m3, or 38.4﹪ of the OOIP. Current oil rates of 1,000 m3/d have fallen from peak rates of 4,400 m3/d. Field average water cut is greater than 90%. Within the EOR area, well spacing is 32 ha., approximately 400 m interwell distance. Geological The internal architecture of this limestone reservoir is multilayered and compartmentalized, due to several stages of carbonate accumulation. From the base up these stages are: S1 (equivalent to the regionally extensive Slave Point platform), S2A, S2, S3L, S3U, and S4, (herein called S-units) reaching a total maximum thickness of 150 m. A high energy windward margin exists along the eastern portion of the build-up with superior reservoir quality (an average range of.09 to.12 phi, and 20 to 120 mD permeability). For this study the S3L in the margin area of the build-up was investigated (Figure 1). Solvent Gravity Override Solvent gravity override (Figure 2) occurs when there is sufficient time for injected solvent to segregate prior to its withdrawal due to gravity differences and therefore a smaller miscible oil target is swept.

Hydrolysis of soybean oil

Subcritical water has been recently demonstrated to be a viable medium for conducting hydrolysis reactions on a variety of organic compounds. In this study, the hydrolysis of triglycerides in soybean oil to their respective free fatty acids has been affected using a flow reactor. The flow reactor permits hydrolysis to be accomplished without the need of a catalyst but requires higher temperatures than previously used in a static system to attain >97% product conversion. Using a high pressure view cell as a diagnostic aid, it was found that the oil miscibility with water is crucial to attaining a high conversion to the free fatty acids. Water to oil ratios of 2.5∶1–5∶1 were found to optimal for high conversions as well as residence time between 10–15 minutes in the open tubular reactor. Such rapid hydrolysis times contrast with multi-hour conversions utilized industrially to achieve a 96–98% fatty acid yield. Although conversion of the all natural cis forms of the fatty acids to some trans form occurred, the isolated products were clear and free of degradation products, unlike previous results reported for the reaction run in a closed vessel under static conditions at these elevated temperatures (>300 °C). Determination of the trans fatty acid content of aqueous hydrolyzed oils has not been previously reported, however they are of minor importance since the produced fatty acid mixtures are primarily intended for industrial utilization and not for food consumption.

Estimation of Volumetric Sweep Efficiency of a Miscible Flood

Abstract Forecasting volumetric sweep efficiency and oil recovery of a miscible flood is difficult, yet reliable production forecasts are required for economic analysis. Conventional decline curve analysis cannot be applied until well after the miscible flood is underway, and may be inapplicable if oil production rates are constant or increasing. Numerical simulation can usually give reliable estimates of oil recovery but only after a time consuming history match. In addition, computer resources and manpower constraints can often limit the areal extent of a simulation model, and therefore limit the model's applicability for full field forecasts. In this study, simple methods based on waterflood surveillance techniques were developed for estimating miscible flood volumetric sweep efficiency. These methods can be used to predict ultimate recovery and volumetric sweep for horizontal miscible floods in either strongly gravity-dominated systems, heterogeneous systems or viscous fingering dominated systems. Miscible flood simulation studies and results from actual field projects show that a plot of gas-oil ratio (GOR) correlates well with cumulative incremental oil production. Such a plot can be used to estimate miscible flood incremental recovery. If the log GOR vs. cumulative oil is a straight line, this implies that the late oil rate decline will be either harmonic or hyperbolic depending upon total fluid production rate. These surveillance techniques can identify areas in which volumetric sweep and oil recovery is performing below expectations. These techniques allow an operator to continuously monitor performance and to make timely operational changes to maximize oil recovery. Introduction It is critical that a development team has an excellent knowledge of reserves remaining in a reservoir to plan optimum depletion strategies. Unfortunately the reservoir engineer has a difficult decision of predicting reserves from decline analysis or simulation. Determining incremental oil in a tertiary miscible flood by decline analysis is especially difficult because:Often daily fluctuations in oil rate may be greater than the incremental oil rates attributed to miscible floodingInfill drilling and well workovers are occurring simultaneously as miscible floods start up so it is difficult to attribute oil production to tertiary miscible responseInitial overall oil rates are constant or increasing These factors mean that conventional decline analysis cannot be applied until well after the miscible flood is underway. For a more "accurate" answer, the reservoir engineer can use numerical simulation but this approach requires detailed reservoir knowledge, usually requires fine detailed grids and is expensive and time consuming. Therefore simulation is limited to only portions of the reservoir. Nevertheless, large capital expenditure decisions need to be made on an ongoing basis. It is therefore critical to determine what the incremental recovery and volumetric sweep are in a timely fashion. Many surveillance techniques that have been developed for waterfloods and gas floods are applicable to miscible floods, with slight modifications. In this paper techniques are derived for gas flood and modified for miscible flood. The techniques are validated using numerical simulation where multiple simulation models are made increasingly more complex and realistic. Finally, field cases are also used to validate the theories.

Technical Feasibility of CO2 Flooding in Weyburn Reservoir - A Laboratory Investigation

Abstract Miscible or near-miscible flooding with CO2 or hydrocarbon gases will significantly increase, and extend the production life of, Saskatchewan light and medium oil reserves. These pools are approaching their economic limit of production under conventional technology (primary and secondary recovery methods). Responding to industry needs, a comprehensive study by Saskatchewan Research Council is assessing the suitability of the CO2 flooding process for reservoirs in southeast Saskatchewan. This paper presents the details of a laboratory study to evaluate the applicability of CO2 flooding for a southeast Saskatchewan reservoir, Weyburn. The evaluation is based on the measurement of CO2 minimum miscibility pressure for the Weyburn reservoir fluid, of PVT properties for reservoir fluid CO2 mixtures, and of oil recovery behaviour from core flood tests conducted in the near-miscible region. Laboratory studies showed that the tertiary CO2 injection at over 12 MPa into the waterflo'oded reservoir is expected to produce miscible flooding conditions. At this pressure of injection, over 60 mol % CO2 was dissolved in the reservoir fluid. This reduced the viscosity of the fluid nearly fourfold to 0.70 mPa.s and swelled the oil about 45%. Coreflood studies indicated that the microscopic displacement efficiency of the process increased with injection pressure in the near-miscible region. It is believed that the geology of the Weybum reservoir will prove advantageous for near-miscible operation. However, this aspect needs to be further investigated. Introduction Most of Saskatchewan's light and medium oil (LMO) reservoirs have reached their economic limit of production under conventional technology. Primary and secondary methods together recover about 21% of the initial oil-in-place (IOlP). Although the remaining light and medium oil-in-place in Saskatchewan is 1,373 million cubic metres(1) the remaining reserves producible under primary and secondary recovery are only 59 million cubic metres. This latter number would rise by 20 million cubic metres if medium oil in southwest Saskatchewan, not considered here, were included(1). The development of tertiary recovery techniques is, therefore, essential to increase the production life of these reservoirs and to maintain current production. Application of the miscible or near miscible oil displacement process using CO2, hydrocarbon or other gases as injection fluids is expected to increase the LMO reserves threefold and extend the production life of these pools by two decades(2). Miscible (or near-miscible) flooding with carbon dioxide or hydrocarbon solvents is considered to be one of the most effective enhanced oil recovery (EOR) processes applicable to LMO reservoirs. A comparison of effectiveness of CO2 and hydrocarbon gases as miscible solvents has been discussed(3). CO2 floods minimize gravity segregation compared with the hydrocarbon solvents. In addition, CO2 generally costs less than hydrocarbon miscible solvents in the United States(3). There is a limited supply of CO2 in Saskatchewan and Alberta for EOR purposes. However, CO2 can be imported from the U.S. to be implemented in miscible displacement projects in Canada. Current industry interest in CO2 miscible flooding is high, as evidenced by the growing level of activity in field testing(4) and increasing production from this method worldwide.