Liquid Phase Of Oil Research Articles

Combined use of petroleum inclusion analysis, PVT simulation, and basin modeling for reconstruction of deep fluid phase evolution in condensate gas reservoirs

The reconstruction of the fluid phase evolution in deep condensate gas reservoirs can reveal the mechanism of condensate gas formation, facilitating the early formulation of drilling strategies. However, the complexity of petroleum fluid phase evolution during hydrocarbon generation, migration, and accumulation poses numerous challenges for the reconstruction process. Therefore, petroleum fluid inclusion analysis, PVT phase simulation, and basin modeling were used to achieve the reconstruction of phase states during key geological periods, elucidating the phase evolution of the deep condensate reservoirs in the Dongying Depression during the whole process. The modeled results show that the mature source rocks contributed to the charging and accumulation of liquid oils (38–14 Ma). Next, a low oil cracking conversion rate limited the increase of gaseous hydrocarbon fraction, so the accumulated hydrocarbons remained in a liquid phase (14–0 Ma). The late external gas inputs significantly increased the gas-oil ratio in the reservoirs, leading to the transition from the liquid oil phase to the condensate phase (5–0 Ma). The fluid compositions obtained from hydrocarbon inclusions and the physical properties of present-day condensates can effectively constrain basin modeling, leading to reliable simulation results. This work revealed that the hydrocarbon generation controls the initial hydrocarbon components in the traps for the phase evolution. Furthermore, the secondary alterations including oil cracking and gas inputs influence the proportion of methane of petroleum in the deep reservoirs, which dominates the phase evolution. Deep petroleum fluid phase changes mainly require the molar ratio of the input gas more than 50%. A model was proposed to explain the formation of deep condensate reservoirs. A series of gas inputs and escape in the successive lithological traps controls an orderly phase change of deep petroleum, and the amount of deeper gas determines the range of the existence of condensate gas reservoirs. This study not only guides the exploration of deep condensate in the Dongying Depression but also offers a workflow for the research on the formation and evolution of condensate reservoirs in other global regions.

RHEOLOGICAL AND COLLOID-STRUCTURAL BEHAVIOUR OF HIGH-VISCOSITY CRUDE OIL AND EMULSION AFTER WAVE ACTION

One of the main problems in oil production is the formation of stable oil-water emulsions that cause corrosion of pipelines, malfunction of pumping equipment, and poisoning of catalysts at refineries. The features of the viscosity-temperature behaviour of high-viscosity resinous crude oil from the Russkoye field (Yamal-Nenets autonomous district) and its 30 wt% emulsion after exposure to electromagnetic and low-frequency acoustic fields are investigated. Electromagnetic treatment of crude oil leads to a decrease in the phase transition temperature and the yield strength coefficient. Low-frequency acoustic processing of the emulsion is accompanied by a decrease in the effective viscosity and the yield strength coefficient. After a complex wave action, the viscosity-temperature characteristics of crude oil continue to fall, and the stability of the formed emulsions decreases due to the intense coalescence of water-phase droplets. It is shown that the amount of released asphaltenes in oil-containing systems decreases after wave treatment. On the contrary, after a complex impact, their content in crude oil increases, while in the emulsion it continues to decrease. This is likely to occur due to the release of hydrocarbons occluded in the asphaltene structure into the liquid oil phase.

Study on dynamical characteristics of cooling fluid in engine piston

The cooling of engine piston is very important, and the fluid vibration characteristics of its internal cooling oil is the key to affect the heat transfer efficiency. In order to effectively ensure that the piston temperature will not be overloaded and avoid the reduction of sealing performance, a two-phase flow model in the piston cooling chamber is established in the paper. The flow field and heat transfer characteristics of the cooling oil are simulated by finite element method using FLUENT. In terms of model selection, VOF multiphase flow calculation and SST k-ω model are selected as turbulence model. The setting of boundary conditions combines the piston stroke characteristics of the hydraulic cylinder, so as to obtain accurate inlet parameters, and obtain the oil liquid phase proportion distribution, oil velocity field and the change law of convective heat transfer coefficient under different piston positions. The results show that the instantaneous ratio of cooling oil is closely related to the speed, and increasing the oil speed is an important means to improve the heat transfer performance. The multiphase flow model has high reliability, and there is no obvious difference between the average convective heat transfer coefficient obtained by the near-wall model method and the wall function method.

Experimental Study on the Effect of Wax Crystal-Water Droplet Aggregations on Wax Deposition of Water-in-Oil Emulsions

Wax deposition in waxy crude oil emulsions remains a flow assurance challenge in offshore production. Wax molecular diffusion driven by the positive temperature gradient from the liquid to the pipe wall has been widely studied and regarded as the primary wax deposition mechanism; however, a considerable wax deposit of emulsions at a zero-temperature difference was detected, in which condition molecular diffusion is not likely to occur, suggesting there were other mechanisms that contribute to wax deposition. In this work, the wax deposition mechanism of water-in-oil emulsions at a zero-temperature difference was explored by a cold finger apparatus regarding the role of wax crystals and water droplets on wax deposition. Through microscopy observation and component measurement of deposits, the wax deposition mechanism, namely, wax crystal-water droplet aggregation formation and adhesion behavior, was proposed. During wax deposition, wax crystals in the emulsion interacted with water droplets, organizing the basic structure of aggregation. The liquid oil phase was entrapped at the inner space of the aggregation and entrained by the wax crystal-water droplet structure to generate a wax deposit. The formation of wax crystal-water droplet aggregations depends on the experimental temperature, where a larger size of aggregations that formed at a lower temperature preferred to yield a thicker deposit under the same stirring speed, while for the same temperature operation conditions, the medium and low speed promoted the adhesion behavior of the aggregations to the cold finger resulting in an increase in deposits; however, the high stirring condition sloughed off the formed deposits, reducing the deposit mass. The findings denote that the presence of wax crystal-water droplet aggregations in emulsion should be considered when describing the wax deposition process at low temperatures.

Термодинамическая модель глубинного происхождения нефти и ее фазового «замерзания»

Based on the deep inorganic concept of the origin of oil and gas deposits, the evolution of these petrogenic reservoirs in the lithosphere is considered. The analysis of phase diagrams and experimental data made it possible to determine two trends in the evolution of non-methane hydrocarbons in the Earth's interior. In the upper mantle, the "metastability" of heavy (with a lower H/C ratio) hydrocarbons increases with depth. However, at temperatures and pressures corresponding to the surface mantle-crustal hydrothermal conditions, the “relative metastability” of heavy hydrocarbons increases with approach to the surface. When deep HCs fluids rise to the surface, petrogenic oil reservoirs are formed as a result of a drop in hydrogen fugacity and a gas → liquid oil phase transition. Under the physical and chemical conditions of an oil reservoir, metastable reversible phase equilibria are established between liquid oil, gas hydrocarbons and CO2 and solid (pseudocrystalline) "mature" and "immature" kerogens of "oil source" rocks. A decrease in hydrogen pressure and temperature leads to a stoichiometric phase transition (“freezing”) of liquid oil into solid kerogens. This occurs as a result of oil dehydrogenation in the processes of high-temperature CO2 fixation and low-temperature hydration of oil hydrocarbons, which are the main geochemical pathways for its transformation into kerogen. Thus, the formation of carbon matter in petrogenic reservoirs is the result of regressive metamorphism of deep hydrocarbon fluids, natural gas, liquid oil, and emerging accumulations of naphthides.

Оleogels – Types, Properties and Their Food, and Other Applications

This review aims to reveal a modality for transforming liquid vegetable oils into semi-solid forms as their mechanical properties can vary from viscous and thick liquids to hard and elastic solids. The edible oleogels are an alternative replacer of undesirable trans and saturated fats. They are porous materials with self-assembled and three-dimensional gel network. Large amount of a continuous edible liquid-oil phase can be entrapped physically and stored in this gel structure. The bigels are a variety of oleogels and they represent two-phase emulsions, containing both oil-based oleogels and water-based hydrogels. The edible oleogels are composed by a structurant substance of food grade in a low concentration, below 10 %. Some of their featured properties are: (i) improved viscosity, spreadability and some of them are semisolid, translucent with semi-crystalline structure; (ii) high physical and structural stability combined with high oil binding capacity; (iii) high-temperature stability, but some of them are thermo-reversible; (iv) higher oxidative stability of oil and the chemical stability of active lipophilic compounds incorporated; (v) microbiological stability. Their more remarkable food applications are chocolates, processed meat products, margarine spreads and shortening. Their combination with other promising techniques raises up new perspectives for structural engineering of foods. There are also outlined other applications of oleogels in cosmetic and pharmaceutical formulations; for engineering purposes and environmental protection. The general limitations, some challenges in the development of new products, their commercialization are also divulged.

High-strength shape-memory organohydrogel based on two orthogonal supramolecular effect: Gelator-induced phase-transition and metal-coordination interaction

• The organohydrogels can be synthesized by simple two-step procedures. • Our SN organohydrogels show high mechanical performances, comparable to DN gels. • The gelator endows liquid oil phase with switchable phase transition properties. • The orthogonal networks endow the gel with a dual-programming shape-memory property. • The shape-morphing behavior with high strength can be used for liquid transport. Shape-memory hydrogels are extensively applied in various fields. However, the existing shape-memory hydrogels with simple shape morphing, such as tensile and bending deformations, cannot satisfy complex and diverse requirements. When the hydrophilic and lipophilic structures were integrated into the same gel network, the heterogeneous structures can be separately controlled by two independent supramolecular interactions. Here, we prepared an organohydrogels with two orthogonal supramolecular networks (metal-coordination interaction of hydrogel framework and gelator-induced phase-transition of organogels inclusions) via photoinitiated polymerization and soaking in Fe 3+ solution. Importantly these two non-interfering orthogonal supramolecular networks endow the gel excellent mechanical properties and a unique dual-programmed shape-memory behavior, enabling highly accessible complex shape deformation, such as kirigami and multidimensional deformations. The organohydrogels can be used to fabricate smart devices for multidimensional on-demand fluid delivery. Consequently, our organohydrogel materials, with sophisticated and high-strength shape-memory properties, can further promote the practical application of gel materials in complex environments.

Investigating the microstructure of soft, microporous matter with synchrotron X-ray tomography

Soft porous matter is commonly encountered in artificial tissue applications, pharmaceuticals delivery systems and in cosmetic and food products. These materials are typically opaque and tend to deform under very small levels of shear; this makes the characterization of their microstructure very challenging, particularly in the native state. Air-in-oil systems (oleofoams) are an emerging type of soft material with promising applications in cosmetics and foods, which contain air bubbles stabilized by Pickering fat crystals dispersed in a liquid oil phase. Synchrotron radiation X-ray computed tomography (SR - XCT) is a non-invasive, non-destructive technique increasingly used to investigate multiphasic, porous materials, owing to its high flux which enables sub-micron resolution and significant statistics at rapid acquisition speed. While the penetration of high energy X-rays can provide high resolution images and allows the reconstruction of the 3D structure of samples, the experimental setup and measuring parameters need to be carefully designed to avoid sample deformation or beam damage. In this work, a robust methodology for investigating the 3D microstructure of soft, porous matter was developed. Sample preparation and experimental setup were chosen to allow synchrotron tomographic analysis of soft oleofoams with a low melting point (<30 °C). In particular, the use of cryogenic conditions (plunge-freeze in liquid nitrogen) provided stability against melting during the acquisition. Additionally, an image processing workflow was designed for analysing the 3D microstructure of the samples using ImageJ. Hence, the size and shape distribution of the air phase, as well as the thickness of the continuous gel phase could be determined for samples with significantly different microstructures (fresh vs. heated). Furthermore, the use of time-resolved X-ray radiography (XRR) allowed to study dynamic changes in the microstructure of the samples during thermal destabilization, visualizing bubble coalescence and growth in optically opaque foam samples with a sub-second timescale. • Synchrotron X-ray tomography was used to characterize oleofoams. • Oleofoams are soft, porous materials used for food, pharma or cosmetic applications. • X-ray tomography and radiography enabled the study of oleofoams' microstructure. • Synchrotron radiation allowed fast measurements and negligible sample damage.

Application of hydrophobic polymers as solidifiers for oil spill cleanup

Oil spill containments are daily life problems due to inherent risks in transporting oil and diluted bitumen products via both tankers and pipelines. For oil–water separation, using a solidifier is one of the most efficient methods which triggers chemical interactions between the solidifier and the spilled oil to change the liquid phase of oil to a coherent mass, through a process called solidification. This study presents the performance of polypropylene (fibers, granule) and polyethylene granule solidifiers for oil spill cleanup by the gravimetric and spectrophotometric methods. The obtained results showed that polypropylene fibers have the highest sorption percentage (82.2%) and sorption capacity (12.5 g/g). The isothermal study reflects the Langmuir isotherm shows the good correlation coefficient (R2 = 0.93) for polypropylene fibers with consistency with the experimental data.

Sensitivity analysis of heat dissipation factors in a hot oil pipeline based on orthogonal experiments.

The study of phase-change heat-transfer characteristics of crude oil has been one of the hot issues in the field of gathering and transportation. The process of phase-change heat transfer of crude oil involves many complicated problems such as natural convection treatment, latent heat treatment, phase-change interface determination and fluid characteristic change. A mathematical model based on the additional capacity heat method is proposed in this article, and the momentum equations of crude oil liquid phase are presented for Newtonian and non-Newtonian fluids. The aim of this study was to investigate the influence of different factors on the heat transfer performance during the shutdown process of an overhead pipe. Experiments were conducted to verify the model and the solution method; the experimental and model results showed good agreement with a maximum relative error of 4.57%. The temperature fields and solidification conditions of crude oil in pipelines under different shutdown conditions were determined, and the sensitivity of the main effect factors was determined through an orthogonal experiment. The results show that the order of influence was oil initial temperature >thickness of insulating layer >air temperature >thickness of wax layer. The results of the study have important guiding significance on the control of shutdown time and the determination of restarting schemes.

Experimental and Numerical Studies on the Diffusion of CO2 from Oil to Water

Injecting CO2 into oil reservoirs can improve the oil recovery, meanwhile achieve CO2 storage. The diffusion of CO2 in oil-water systems has a substantial impact on this process. The interface significantly affects the mass transfer of CO2 between oil and water phase. In this paper, based on the determination of the CO2 diffusion coefficient in oil or water phases, the diffusion processes of CO2 from oil to water were experimentally investigated under different pressures. A numerical method was proposed to calculate the pressure drop and the diffusion coefficient in the process of CO2 diffusion from oil to water. The experimental results indicated that the CO2 diffusion coefficient in oil or water increased rapidly with pressure up to the critical pressure of CO2 and gradually slowed down thereafter. The CO2 diffusion from oil to water was much slower than that in oil or water. The diffusion coefficient of CO2 from oil to water was one magnitude lower than that in the single liquid phase of oil or water, and the effect of pressure was not significant. Based on the diffusion coefficient of CO2 in a single liquid phase and the proposed numerical method, the pressure drop and the numerical diffusion coefficient in the process of CO2 diffusion from oil to water were calculated. The relative errors between the experimental and numerical results were within 9%. Therefore, the numerical method proposed herein can be used to predict the diffusion process of CO2 from oil to water and the diffusion coefficient associated with this process.

Spontaneous nano-emulsification with tailor-made amphiphilic polymers and related monomers

In general, nano-emulsions are submicron droplets composed of liquid oil phase dispersed in liquid aqueous bulk phase. They are stable and very powerful systems when it regards the encapsulation of lipophilic compounds and their dispersion in aqueous medium. On the other hand, when the properties of the nano-emulsions aim to be modified, e.g. for changing their surface properties, decorating the droplets with targeting ligands, or modifying the surface charge, the dynamic liquid / liquid interfaces make it relatively challenging. In this study, we have explored the development of nano-emulsions which were not anymore stabilized with a classical low-molecular weight surfactant, but instead, with an amphiphilic polymer based on poly(maleic anhydride-alt-1-octadecene) (PMAO) and Jeffamine®, a hydrophilic amino-terminated PPG/PEG copolymer. Using a polymer as stabilizer is a potential solution for the nano-emulsion functionalization, ensuring the droplet stabilization as well as being a platform for the droplet decoration with ligands (for instance after addition of function groups in the terminations of the chains). The main idea of the present work was to understand if the spontaneous emulsification –commonly performed with nonionic surfactants– can be transposed with amphiphilic polymers, and a secondary objective was to identify the main parameters impacting on the process. PMAO was modified with two different Jeffamine®, additionally different oils and different formulation conditions were evaluated. As a control, the parent monomer, octadecyl succinic anhydride (OSA) was also modified and studied in the similar way as that of polymer. The generated nano-emulsions were mainly studied by dynamic light scattering and electron microscopy, that allows discriminating the crucial parameters in the spontaneous process, originally conducted with polymers as only stabilizer.

Effectiveness of supercritical-CO2 and N2 huff-and-puff methods of enhanced oil recovery in shale fracture networks using microfluidic experiments

Current oil recovery methods in hydraulically fractured shale reservoirs have a low recovery efficiency of about 10%. The objective of this work is to investigate the effectiveness of nitrogen and supercritical carbon dioxide in the huff-and-puff method for enhanced oil recovery as a means to re-energize reservoirs and improve recovery rates. We conduct direct visualization experiments with a microfluidic system to reveal the mechanisms and to quantify the recovery rates of oil from fracture networks. We compared the effectiveness of water, nitrogen and supercritical carbon dioxide at reservoir conditions in a process mimicking the huff-and-puff method in both dead-end and connected fracture systems. The microfluidic chips were made of glass and placed in a confining pressure system pressurized to 10 MPa, 50 °C. The system was allowed to equilibrate, and then depressurized to simulate huff-and-puff oil recovery. Fluorescence microscope images were continuously taken to visualize and calculate residual oil saturation as a function of pressure drawdown. As the system was depressurized from 10 MPa, gas exsolution from the oil liquid phase, including bubble nucleation, growth, and coalescence, appeared to be the main driver for mobilizing oil from the fracture networks. Injection of supercritical CO2 resulted in the highest recovery rate with an average end-point recovery of about 90% in the connected fracture network and 60% in the dead-end fracture network. N2 has lower solubility in oil and hence showed a lower recovery rate of 40% in the connected fracture network and 25% in the dead-end fracture network. Injection of water had no effect on oil mobilization since water is insoluble, immiscible and incompressible. The main mechanism of enhanced recovery was gas exsolution from the liquid phase as pressure was decreased below the bubble point pressure. Because the gas was distributed throughout the oil phase, bubble nucleation, growth, coalescence, and elongation occurred throughout the fracture network. Expansion of the gas forced oil out of the network through piston displacement in continuous oil areas and film flow in the dispersed oil areas. Bubbles began as spheres and grew until they touched the fracture walls where they elongated along the fracture length. The bubble growth rate depended on local mass transfer from liquid to gas phase and gas volume expansion due to pressure drop. The efficiency of the huff-and-puff process is dependent on the solubility and miscibility of the injection fluid with oil. High gas solubility allows for more bubble nucleation, growth and expansion during the depressurization cycle.

Vapor-Phase Combustion in Accelerating Rate Calorimetry for Air-Injection Enhanced-Oil-Recovery Processes

Summary The accelerating rate calorimeter (ARC) is unique for its versatility of operation and application—reliability, validity, and accuracy of results—caused by very-high adiabaticity. Accelerating rate calorimetry is one of the screening tests used to determine the suitability of a reservoir for air-injection enhanced oil recovery. The ARC is well-suited for investigating the reaction mechanisms in the low-temperature range (LTR), negative-temperature-gradient region (NTGR), and high-temperature range (HTR). The ARC provides full time–temperature, time–pressure, and self-heat rate-inverse absolute-temperature profiles. An experimental and simulation study is carried out to expand knowledge and interpretation of the data derived from high-pressure closed ARC tests. Athabasca bitumen is used for the experimental study in a closed ARC at an initial pressure of 13.8 MPag (2,000 psig) to identify the nature of the oxidation reactions occurring over the different temperature ranges. The simulation component of the study focused on the development of a numerical model that captured the elements of the ARC test. The model incorporated solubility of oxygen and diffusion to control the transfer of oxygen in the liquid-oil phase. Mass transfer is found to play an important role at low temperatures up to the temperature at which chemical interaction starts to control the distribution of oxygen within the liquid bitumen. Likewise, vaporization of oil and generation of vapor by cracking reactions are also believed to play an important role in air-injection processes. Therefore, a vapor-phase combustion reaction is integrated into the traditional Belgrave kinetic model. This modified model predicted that the combustion of vaporized oil integrated with its flammable limits and the rate of diffusion of the vaporized component in the gas phase. The results of this study indicate that, with the addition of mass transfer to the kinetic model, it is possible to predict the NTGR. The result showed that solubility and diffusion of oxygen played an important role up to a temperature of 125°C at which chemical reactions started to control the distribution of oxygen within the liquid bitumen. The results also showed that vapor-phase combustion creates a temperature gradient between the gas and bitumen phases when vaporized components became flammable (stoichiometry). This showed that the ARC could be an effective tool for understanding liquid and vapor-phase reaction and their relative importance in different temperature regimes.

Factors affecting the rheological properties of a structured cellular solid used as a fat mimetic

The effects of water content, monoglyceride chain length and concentration, oil type, and the addition of oil-phase and water-phase additives on the elastic modulus and yield stress of a structured oil in water were evaluated. The goal was to increase the elastic modulus of the original emulsion from 8.42×103±11.3Pa to 1.55×106±2.1×105Pa, and the yield stress from 112±2.31Pa to 835±227Pa. The addition of wax at greater than 10% (w/w), the use of palm oil or the gelation of the liquid oil phase with 5–7.5% rice bran wax, the use of C-18 saturated monoglyceride at 6%(w/w), and 4% (w/w) for C-22 saturated monoglyceride molecules were effective modifications capable of improving the mechanical behavior of the emulsion so that it can be used as a zero trans and reduced saturated fat laminating shortening substitute for puff pastry products.

Characterization of organic matter fractions in an unconventional tight gas siltstone reservoir

This paper on core samples collected from the Triassic Montney Formation tight gas reservoir in the Western Canadian Sedimentary Basin (WCSB) illustrates that operationally-defined S1 and S2 hydrocarbon peaks from conventional Rock–Eval analysis may not adequately characterize the organic constituents of unconventional reservoir rocks. Modification of the thermal recipe for Rock–Eval analysis in conjunction with manual peak integration provides important information with significance for the evaluation of reservoir quality. An adapted method of the analysis, herein called the extended slow heating (ESH) cycle, was developed in which the heating rate was slowed to 10°C per minute over an extended temperature range (from 150 to 650°C). For Montney core samples within the wet gas window, this method provided quantitative distinctions between major organic matter (OM) components of the rock. We show that the traditional S1 and S2 peaks can now be quantitatively divided into three components: (S1ESH) free light oil (S2aESH) fluid-like hydrocarbon residue (FHR), and (S2bESH+residual carbon) solid bitumen (more refractory, consolidated bitumen/pyrobitumen).The majority of the total organic carbon (TOC) in the studied Montney core samples consists of solid bitumen that represents a former liquid oil phase which migrated into the larger paleo-intergranular pore spaces. Physicochemical changes to the oil led to the precipitation of asphaltene aggregates. Subsequent diagenetic and thermal cracking processes further consolidated these asphaltene aggregates into “lumps” of solid bitumen (or pyrobitumen at higher thermal maturity). Solid bitumen obstructs porosity and hinders fluid flow, and thus shows strong negative correlations with reservoir qualities such as porosity and pore throat size.Although the FHR fraction constitutes a small portion of the total rock mass and volume in Montney samples it has important implications for reservoir quality. This fraction represents a thin film of condensed, heavy molecular hydrocarbon residue covering surfaces of the present-time pore spaces and may represent the lighter component of the paleo-oil that migrated into tight interstices in the Montney reservoir. The FHR fraction potentially plays an important role in wettability alteration by creating hydrophobic matrix pore networks in portions of the reservoir that were not already filled with solid bitumen.

Solid bitumen as a determinant of reservoir quality in an unconventional tight gas siltstone play

In this study of the Triassic Montney tight gas siltstone play in the Western Canadian Sedimentary Basin petrophysical measurements of drill-core samples (porosity, pore throat size, water saturation and grain size) are integrated with Rock-Eval TOC data, organic petrography observations and SEM imaging to show that reservoir quality in the gas window is strongly influenced by the pervasive presence of pore-occluding solid bitumen (and pyrobitumen at higher thermal maturity). The solid bitumen formed as a pore-filling liquid oil phase that was diagenetically and thermally degraded with further burial and increase in temperature. The proportion of solid bitumen filling the intergranular paleopore network can be expressed as bitumen saturation, and this attribute is found to be the dominant control on pore throat size and absolute permeability. The samples with low bitumen saturation and large pore throat radius (>0.01μm) have water saturations that generally increase as pore throat size diminishes, a relationship consistent with capillary theory for conventional water wet conditions. The samples with high bitumen saturation and small pore throat radius (<0.01μm), on the other hand, have abnormally low water saturation, a condition inconsistent with capillary theory for conventional water wet rocks. The coincidence of small pore throat size, low water saturation and high bitumen saturation is attributed to the presence of well-connected nanopores within the devolatilized, solid bitumen and the hydrophobic nature of the bitumen. Siltstones in economic portions of the Montney tight gas fairway have porosity mostly in the range of 3 to 7%. The results of this study show that reservoir quality in this economically key porosity range is influenced more strongly by bitumen saturation than by conventional determinants of porosity and permeability such as grain size, sorting, clay content and cementation. The concept of pore-occluding solid bitumen as an important negative control of reservoir quality elucidated here for Montney siltstones likely has application to the technical and economic evaluation of other tight gas plays particularly those in indirect basin-centered gas accumulations.

Liquid phase optimisation in a horizontal flow biofilm reactor (HFBR) technology for the removal of methane at low temperatures

Methane (CH4) is a potent greenhouse gas often emitted in low concentrations from waste sector activities. Biological oxidation techniques have the potential to offer effective methods for the remediation of such emissions. In this paper, methods of improving the CH4 oxidation performance of a horizontal flow biofilm reactor (HFBR) technology, operated at low temperatures, are investigated.Three pilot scale HFBRs were operated over three studies (Study 1, 2 & 3) lasting 310days in total. The reactors were loaded with 13.2g CH4/m3/h during each study and operated at an average temperature of 10°C.In Study 1, nutrients were added to the biofilm via a liquid nutrient feed (LNF) comprising water and nutrient mineral salts. Average removals were 4.2, 3.1 and 2.3g CH4/m3/h for HFBRs 1, 2 and 3 respectively.In Study 2 silicone oil was added to the LNF of all three HFBRs. Average removals increased, when compared to Study 1, by 31%, 79% and 78% for HFBRs 1, 2 and 3 respectively.In Study 3 a non ionic surfactant (Brij 35) was added to the LNF and silicone oil liquid phase of HFBRs 1 and 2. The operating conditions of HFBR 3 were not changed and it was used as a control. A concentration of 1.0g Brij 35/L proved most effective in improving reactor performance; with removal rates increasing by 105% and 171% for HFBRs 1 and 2 respectively when compared to Study 1.These results indicate the potential of liquid phase optimisation for improving mass transfer rates and removal performances in biological reactors treating CH4.

Supercritical extraction of crude oil by methanol- and ethanol-modified carbon dioxide

The effect of ethanol and methanol cosolvents on the extraction yield and kinetics of crude oil originating from the Halfdan field of the North Sea by supercritical carbon dioxide was investigated across a pressure range of 20–60MPa under a fixed temperature of 60°C. Results inform that the pure carbon dioxide recovery varied between 43 and 77% while the recovery of the liquid phase of oil ranged between 22 and 56% across the entire pressure range. Using ethanol- and methanol-modified CO2, the total recovery yield increased significantly averaging an additional 18.2% and 19.4% respectively when compared to pure carbon dioxide. The ethanol addition improved the recovery of the liquid phase of oil averaging 9.6% while the methanol addition improved it to 7.3% across the entire pressure range.Study of the kinetics of extraction process indicated that heavier fractions were extracted faster with the ethanol- compared to the methanol-modified CO2. GC–MS TIC chromatographic analysis of the extracted oil fractions showed that the extraction of C19-C30 single carbon number groups with the addition of methanol is more dependent on pressure. Predominantly, ethanol addition was more efficient in extraction of C17-C38 single carbon number groups while methanol contributed more in extraction of C7-C9 SCN groups.

Application of microwave reflectometry to disordered petroleum multiphase flow study

Microwave reflectometry is applied to multiphase flow metering in the context of oil extraction. Our sensor consists of two open-ended coaxial probes operating at complementary frequencies (at 600 MHz and around 36 GHz) and was designed to resist harsh field conditions. This paper presents and comments on results obtained in realistic dynamic conditions, on a triphasic flow loop (water–oil–gas). The main conclusions are the following: Bruggeman–Hanai's mixing rule applies to natural emulsions and can be used to determine the composition of the water–oil liquid phase; results obtained for annular flows are very sensitive to small perturbations such as bubbles or waves at the liquid–gas interface; in the case of triphasic slug flows, the composition of the liquid phase can be estimated by proper filtering of the data.