A computational scheme for calculating the temperature field when oil production problems

The paper presents an approach to coupled modeling of hydrodynamic and thermal processes occurring in the oil reservoir during field development using thermal methods of enhanced oil recovery. To simulate the processes of non-isothermal multiphase flow, an approach based on implicit calculation of pressure using the finite element method and an explicit calculation of phase saturations is used. A computational scheme for calculating the temperature field is considered. This scheme makes it possible to take into account both heat transfer between phases and heat transfer of a fluid mixture and matrix-rock. In order to take into account the effect of thermal conductivity, a coefficient characterizing the rate of heat transfer between the fluid mixture and the rock is used. The proposed scheme also takes into account the effect of the temperature field on the phases flow in the field reservoir and provides for the possibility of heat sources and sinks occured due to chemical reactions or thermodynamic processes in gaseous phases. Numerical experiments were carried out on a model of a real oil field obtained as a result of history matching of well data. The model contains a large number of wells and is characterized by a high heterogeneity of the porous medium. The applicability of the considered computational scheme is demonstrated on the example of modeling hot water injection into wells crossing a formation with super-viscous oil. The efficiency of thermal methods for the development of super-viscous oil fields is shown. When hot water was injected into the reservoir, the increase in oil production was about 25 % due to a significant decrease in oil viscosity. The time spent for calculating the temperature field while simulating a multiphase flow did not exceed 6 % of the total computational time.

Additives Imparting Antimicrobial Properties to Acrylic Bone Cements

PMMA bone cements are mainly used to fix implanted prostheses and are introduced as a fluid mixture, which hardens over time. The problem of infected prosthesis could be solved due to the development of some new antibacterial bone cements. In this paper, we show the results obtained to develop four different modified PMMA bone cements by using antimicrobial additives, such as gentamicin, peppermint oil incorporated in hydroxyapatite, and silver nanoparticles incorporated in a ceramic glass matrix (2 and 4%). The structure and morphology of the modified bone cements were investigated by SEM and EDS. We perform experimental measurements on wettability, hydration degree, and degradation degree after immersion in simulated body fluid. The cytotoxicity was evaluated by MTT assay using the human MG-63 cell line. Antimicrobial properties were checked against standard strains Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The addition of antimicrobial agents did not significantly affect the hydration and degradation degree. In terms of biocompatibility assessed by the MTT test, all experimental PMMA bone cements are biocompatible. The performance of bone cements with peppermint essential oil and silver nanoparticles against these two pathogens suggests that these antibacterial additives look promising to be used in clinical practice against bacterial infection.

Thermodynamics-Informed Neural Network (TINN) for Phase Equilibrium Calculations Considering Capillary Pressure

The thermodynamic properties of fluid mixtures play a crucial role in designing physically meaningful models and robust algorithms for simulating multi-component multi-phase flow in subsurface, which is needed for many subsurface applications. In this context, the equation-of-state-based flash calculation used to predict the equilibrium properties of each phase for a given fluid mixture going through phase splitting is a crucial component, and often a bottleneck, of multi-phase flow simulations. In this paper, a capillarity-wise Thermodynamics-Informed Neural Network is developed for the first time to propose a fast, accurate and robust approach calculating phase equilibrium properties for unconventional reservoirs. The trained model performs well in both phase stability tests and phase splitting calculations in a large range of reservoir conditions, which enables further multi-component multi-phase flow simulations with a strong thermodynamic basis.

PSVII-16 Effects of different forms of Cu on in vitro ruminal fermentation and digestibility of a lactation diet

Vistore® mineral products are hydroxychloride minerals that feature high metal content and improved bioavailability. This study was conducted to compare different sources of copper (Cu) on in vitro rumen fermentation parameters. Three ruminally-cannulated Jersey heifers were adapted to a lactation diet for two weeks before being used as donors. Three sources of Cu at 4 ppm: No supplemental Cu (CON), CuSO4, Vistore Cu, and another Cy hydroxychloride product (Vistore-competitor). The concentration of Cu in this study was selected from a titration study (0 to 8 ppm CuSO4) to identify the minimum concentration of CuSO4 affecting rumen fermentation. The lactation diet (TMR) was dried and ground to 1mm and used as the substrate. Rumen fluid was collected two hours after feeding. Substrate (0.5 g) was inoculated with 100 mL of a 3:1 McDougall’s buffer: ruminal fluid mixture at 39ºC for 24 h. Each treatment was run in triplicate and in three runs. Data were analyzed with R 4.0. The model included fixed effect of treatment and random effect of run. CuSO4 tended to increase lag time (0.78 vs -0.57 h, P = 0.06), reduced (P < 0.05) DMD (52.4 vs. 56.1%), cellulose digestibility (4.9% vs. 41.9%), isobutyrate molar % (0.58 vs. 0.78%) and NH3-N concentration (5.46 vs. 6.91 mg/dL). Vistore and Vistore-competitor maintained the fermentation and digestibility compared to CON. In general, Vistore Cu and Vistore-competitor maintained ruminal fermentation and digestibility parameters while negative effects of CuSO4 were observed. These results indicate different Cu mineral sources may affect the rumen differently.

Blast from the Past, Solving Severe Congealed Oil Problems by Combining Existing Solutions

A mature field in central Sumatra, Indonesia, has been producing heavy oil for decades, and it has shown decreased production. The ESP, as the main lifting method, needs to be replaced more frequently due to mechanical damage by congealed oil. Many wells in that field were forced to be deactivated because of congealed oil plugging along the wellbore. The conventional method to tackle this issue is to pump hot water. This practice however did not give sustainable results after the treatment. The remedy of coiled tubing (CT) well cleanout with a wash nozzle has also not been considered successful because the congealed oil is too hard to penetrate. Furthermore, using mechanical devices such as CT milling tools has not been effective because the deposits stick to the mill. Considering the low-production-rate wells, high-rate fluid injection was proposed to meet cost criteria. Although the well was able to produce afterwards, production kept declining due to the production of congealed oil from the formation. A combination of high-pressure jetting tool and organic dissolver fluid was proposed as an alternative method to break the congealed oil. The method uses kinetic energy from the jetting tool to shatter the solidified oil by pumping brine. Afterwards, a fluid mixture composed of organic dissolver and additive is pumped to dissolve the remaining congealed oil. Following the treatments, the pilot well showed significant improvements. The treatment successfully revived well production after the well had stopped producing for more than 3 months. The flowback tank was filled with as much as 10-in.-deep broken oil residue. Such a solid removal has not been accomplished with any other technique. The well has been producing for more than 10 months without any pump issues, and production continues to increase. Another three well candidates with low productivity issues were treated with the same technique. All the wells delivered good results. If, in the future, the congealed oil accumulates again, high-pressure jetting and organic dissolver will be the first method used for remediation. All the wells treated with this approach have been producing significantly more than those treated using any other technique, well beyond the target set by the operator. This study discusses the benefits of combining the techniques of high-pressure jetting, organic dissolver, and high-rate injection to overcome severe congealed oil problems that impair well production. Details the approach are provided, and its effectiveness is compared to other former attempts to solve the congealed oil problem. This case also illustrates the importance of maintaining well interventions to improve production while meeting the cost criteria in this challenging time in the oil and gas industry.

Low Reynolds Number Swimming Near Interfaces in Multi-Fluid Media

Microorganisms often swim within heterogeneous fluid media composed of multiple materials with very different properties. The swimming speed is greatly affected by the composition and rheology of the fluidic environment. In addition, biological locomotions are also strongly influenced by the presence of phase boundaries and free interfaces, across which physical properties of the fluid media may vary significantly. Using a two-fluid immersed boundary method, we investigate the classical Taylor’s swimming sheet problem near interfaces within multi-fluid media. The accuracy of the methodology is illustrated through comparisons with analytical solutions. Our simulation results indicate that the interface dynamics and phase separation in the multi-fluid mixture are closely coupled with the movement of the swimmer. Depending on the interface location, the frictional coefficient, and the multi-fluid composition, the swimmer can move faster or slower than that in a single phase fluid.

Bulk Modulus of Hydrocarbon Fluids After Injection with Supercritical CO2 at Reservoir Conditions

The mechanical properties of hydrocarbon reservoirs significantly depend on the elastic properties of the fluids occupying the pore space in the rock frame. Accurate data and models for the mechanical properties of fluid mixtures in a petroleum reservoir containing supercritical CO2 should be available at the same reservoir conditions for reliable design of well-completion, maximizing reservoir productivity, and minimizing risk in drilling operations. This work investigates the change in the bulk modulus of the higher hydrocarbon fluid (decane C10H22) after the injection with supercritical CO2 at reservoir conditions. The isothermal bulk modulus βT of liquids under pressure, simply defined as the first-order derivative of pressure with respect to volume, is determined in this study from the derivative of pressure with respect to density. The density data were obtained from experimental measurements of mixtures of supercritical CO2 + C10H22 for a range of CO2 mole fractions from 0 to 0.73, at temperatures from 40 to 137 °C and pressures up to 12000 psi. The isothermal derivative coefficients of the pressure as a function of density are reported for each CO2 concentration measured in this work. Common fluid-substitution models, including the Gassmann model, which is only valid for the isothermal regime, have limited predictive power because most fluids are treated as simple fluids, with their mechanical properties only characterized by their densities. However, under different environments, such as when supercritical CO2 is injected into the geological formation, the fluid phase and its mechanical properties can vary dramatically. At high pressure, the density of CO2 can equal to that of the hydrocarbon phase ρ(CO2)/ρ(C10H22) ≈ 1, while the bulk modulus of CO2 remains as low as only βT(CO2)/βT(C10H22) ≈ 7 %. Excessive decrease in the bulk modulus can easily cause subsidence, although the pore pressure and the fluid mixture density remain unchanged, even at pressures up to 4000 psi.

Two-Pressure Model of Particle-Fluid Mixture Flow with Pressure-Dependent Viscosity in a Porous Medium

Equations governing the flow of a fluid-particle mixture with variable viscosity through a porous structure are developed. Method of intrinsic volume averaging is used to average Saffman’s dusty gas equations. A modelling flexibility is offered in this work by introducing a dust-phase partial pressure in the governing equations, interpreted as the pressure necessary to maintain a uniform particle distribution in the flow field. Viscosity of the fluid-particle mixture is assumed to be variable, with variations in viscosity being due to fluid pressure. Particles are assumed spherical and Stokes’ coefficient of resistance is expressed in terms of the pressure-dependent fluid viscosity. Both Darcy resistance and the Forchheimer micro-inertial effects are accounted for in the developed model

A regularized isothermal phase-field model of two-phase solid–fluid mixture and its spatial dissipative discretization equations

The present paper is devoted to a model describing a two-phase isothermal mixture, in which one of the phases obeys solid-like (namely, elastic) rheology. A fully Eulerian description is considered. To describe the stress–strain behaviour of the solid phase the elastic energy term is added to the Helmholtz free energy. The term depends on Almansi strain tensor. In its turn, the strain tensor is defined as the solution of the corresponding evolutionary equation. Considered model belongs to the phase field family. Formally it describes two-component mixture and uses mass densities of the components as order parameters. A distinctive feature of the considered model is its preliminary regularization according to the quasi-hydrodynamic framework. The dissipativity in total energy is proved when periodic boundary conditions are imposed. A spatial dissipative semi-discrete (continuous in time and discrete in space) scheme based on staggered grids is suggested. The theoretical results remain valid in the absence of the regularization. The results of a numerical study in a 2D setting are presented.