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A downhole fluid analysis prototype module (MRPV) has been developed which measures both asphaltene onset pressure (AOP) and bubblepoint pressure (Pb). This manuscript describes one of many recent downhole jobs which were part of a study to characterize live crude oil in real time while sampling mobile oil in a permeable tar mat. These jobs support an enhanced oil recovery (EOR) study to understand the best way to extract bypassed oil (Fatma 2019). In this manuscript, downhole bubblepoint and AOP measurements made with the MRPV in well RA-0Y37 agree with those obtained in a laboratory with bottomhole samples. The effect of oil-based mud contamination on the AOP and Pb is examined during clean up while sampling. Water was present for all jobs, but the hydrophobic membrane blocked water from entering the MRPV, facilitating ease of interpretation of optical data. This manuscript comprises the first part of a two-part series (Tiwari 2020).

We report a novel means of nucleating a second phase using a miniature thermal nucleation source that operates with fluid mixtures at elevated temperature and pressure. This rapid nucleation source locally creates a short-lived (millisecond) but large (up to 10 7 K/m) thermal gradient that we exploit to overcome the nucleation barrier in single and multicomponent fluids, eliminating the need for traditional mechanical agitation. We find good agreement between the phase envelope measured with this method and that measured using a conventional apparatus with mechanical agitation acting as a nucleation source for several binary alkane mixtures. Consistent with expectations, we find that thermal nucleation cannot trigger production of a second phase for temperatures and pressures higher than that of the critical point for single-component fluids, However, we find a range of temperatures and pressures completely outside the phase envelope for multi-component mixtures where thermal nucleation temporarily and anomalously appears to produce a second phase, contrary to expectations based on equilibrium thermodynamics. The relationship between the magnitude of undersaturation and the rate of bubble dissolution is studied in single and multi-component fluids. Direct observations of the morphology that is created during nucleation reveal a sharp interface between coalescing droplets, consistent with the second phase possessing an interfacial tension with respect to the continuous phase.

The accuracy of the phase envelope calculated for a black oil sample strongly depends upon the quality and type of information used to optimize the equation of state (EOS). Possible inputs for EOS tuning include (but is not limited to) composition from a chromatogram or optical absorbance, density, saturation pressure (bubble or dew point pressure), and the relative volumes of liquid and gas. In this manuscript, we describe a workflow using a system of microsensors that our group has previously published that accurately measures fluid properties from which the phase envelopes of several black oil samples are calculated and refined.

A shallow, unconsolidated, sour heavy oil reservoir in North Kuwait is under primary production. Due to rapid decline in reservoir pressure, a development scenario was selected consisting of 10 years of water injection secondary recovery followed by enhanced oil recovery (EOR) polymer flood for which a pilot is being implemented. This pilot will provide vital information to establish feasibility for full-field implementation and in this paper, we describe the application of Interference Pressure Transient Test (IPTT) and stress testing. IPTT is utilized for proper understanding of the vertical permeability and permeability anisotropy (Kv/Kh) which are key for evaluating heavy oil sweep efficiency under injection. Stress testing will provide essential information about the cap rock integrity to monitor that water and polymer flooding is contained across the required reservoir. A combination of IPTT and stress testing utilizing the Wireline Formation Testing (WFT) tool and laboratory core analysis were the basis of a selected method for vertical permeability and permeability anisotropy determination. Laboratory measurement for permeability anisotropy has its own challenge due to unconsolidated nature of the formation. IPTT under such conditions can provide reliable and fast measurements, which can also help to calibrate the laboratory measurements later. Four EOR pilot vertical injectors wells were drilled in a symmetric 5-spot pattern, with a central vertical producer. Distance between the injectors is 60 meters, whereas each injector is at 50 meters spacing from the central producer. IPTT was carried out in all four EOR pilot wells, whereas this study involves only three of the injectors. Three-probe configuration along with advanced three-dimensional probe provided comprehensive evaluation for the sand and shaly reservoir intervals. It was observed that main sand body under consideration showed Kv/Kh ranging between 0.05 to 0.15. Some of the main shaly intervals were observed to be either fully isolating the sub-layers or have some vertical communication. It should be noted that downhole fluid analysis and sampling was conducted in one of the wells utilizing WFT. The obtained fluid properties were included in the IPTT analysis for more accurate results. The acquired data from three pilot wells were used to update the reservoir simulation models to have a more representative sweep efficiency evaluation utilizing polymer flooding for the planned EOR. It provides an efficient way to derive the vertical permeability and permeability anisotropy in the challenging unconsolidated formation. This paper adds to the literature of case studies where vertical permeability and permeability anisotropy have been obtained in the challenging environment of unconsolidated formation. It demonstrates how accurate planning combined with advanced technology and innovative workflow yielded the required input data for the dynamic reservoir simulation model.

We present a highly miniaturized sensor for performing accurate on-chip detection of gas equilibration (bubble point) pressures in liquids, which is manufactured using low-cost batch microelectromechanical system technology. The measurement of gas equilibration (bubble point) pressures in liquids has a diverse spectrum of applications ranging from the oil industry, where the bubble point of a crude oil is important for making informed decisions on production and exploration, to the fisheries industry, where gas saturation needs to be controlled to ensure animal health. Oilfield measurements of bubble point pressures often require acquisition of large sample volumes that are subsequently investigated off-line in laboratory facilities, with important consequences on both cost and operational response times. The present work demonstrates the potential of microelectromechanical system technology to respond to such diverse industry needs by providing an economical solution able to perform in situ real-time mon...

We report a novel method to rapidly nucleate vapor in a liquid with an electrically pulsed wire that temporarily raises the temperature of nearby liquid. This temperature increase is sufficient to overcome the nucleation barrier to vapor formation by locally putting the system in a non-equilibrium superheated state. By observing the subsequent behavior of bubbles after nucleation and thermal relaxation, we can determine the stability of the vapor phase. We map out a phase envelope by adjustment of the ambient temperature and pressure of the fluid around the wire. We find good agreement between measurements with this method and those made using a conventional apparatus. Surprisingly, we find that rapid heating of the liquid around the wire is able to produce nucleation in certain fluid mixtures for which the temperature increase is not expected to create an unstable or even metastable liquid. Evidence suggests a temporary enrichment of the region around the wire by lighter components due to the Soret effect is responsible for nucleation in such cases.

A model was developed for the analysis of steady and unsteady bubble generation frequencies in a microfluidic flow-focusing device. In both cases, the generation frequency depends on the downstream influence of bubbles created by the flow-focusing device, which provides a source of feedback. For steady-state generation of bubbles, this feedback explains the relationships among frequency, gas pressure and liquid flow rate in our experiments as well as gives a physical explanation for previously observed frequency relations. The role of feedback is also exploited to explain unsteady behaviour; we develop a numerical model and analytical expressions that agree with experimental measurements.

We have used a variety of different applied fields to control the density, growth, and structure of colloidal crystals. Gravity exerts a body force proportional to the buoyant mass and in equilibrium produces a height-dependent concentration profile. A similar body force can be obtained with electric fields on charged particles (electrophoresis), a temperature gradient on all particles, or an electric field gradient on uncharged particles (dielectrophoresis). The last is particularly interesting since its magnitude and sign can be changed by tuning the applied frequency. We study these effects in bulk (making 'dielectrophoretic bottles' or traps), to control concentration profiles during nucleation and growth and near surfaces. We also study control of non-spherical and optically anisotropic particles with the light field from laser tweezers.

The trajectory of a stream of bubbles is measured in a microfluidic pressure-driven flow. For Newtonian fluids with or without surfactants, or viscoelastic fluids without surfactants, the bubbles maintain stable positions equally spaced along the channel center line. However, for viscoelastic fluids with surfactant, a transverse instability is observed, which has the characteristics of a linear instability, whose growth rate increases with the speed of the flow. The results are shown to be consistent with the action of shear-induced normal stresses in the fluid, where the magnitude increases with shear rate and so is augmented by surfactants that make the interface rigid.

Oil–water mixtures are ubiquitous in nature and are particularly important in biology and industry. Usually additives are used to prevent the liquid droplets from coalescing. Here, we show that stabilization can also be obtained from electrostatics, because of the well known remarkable properties of water. Preferential ion uptake leads to a tunable droplet charge and surprisingly stable, additive-free, water-in-oil emulsions that can crystallize. For particle-stabilized (“Pickering”) emulsions we find that even extremely hydrophobic, nonwetting particles can be strongly bound to (like-charged) oil–water interfaces because of image charge effects. These basic insights are important for emulsion production, encapsulation, and (self-)assembly, as we demonstrate by fabricating a diversity of structures in bulk, on surfaces, and in confined geometries.

Particle concentration is a dominant control parameter for colloids and other soft matter systems. We demonstrate a simple technique, ``dielectrophoretic equilibrium,'' implemented as an ``electric bottle,'' a planar capacitor in a larger volume. The uniform $E$ field in the capacitor traps particles in this force-free region at a higher density than in the zero field regions outside. We show how the technique measures the equation of state and we initiate and grow colloidal crystals. ``Dielectrophoretic equilibria'' enable the study of a complete concentration-dependent phase diagram from a single microscopic sample, obviating the previous need for preparing a large number of samples.

Recent simulations indicate that ellipsoids can pack randomly more densely than spheres and, remarkably, for axes ratios near $1.25\ensuremath{\mathbin:}1\ensuremath{\mathbin:}0.8$ can approach the densest crystal packing (fcc) of spheres, with a packing fraction of 74%. We demonstrate that such dense packings are realizable. We introduce a novel way of determining packing density for a finite sample that minimizes surface effects. We have fabricated ellipsoids and show that, in a sphere, the radial packing fraction $\ensuremath{\phi}(r)$ can be obtained from $V(h)$, the volume of added fluid to fill the sphere to height $h$. We also obtain $\ensuremath{\phi}(r)$ from a magnetic resonance imaging scan. The measurements of the overall density ${\ensuremath{\phi}}_{\mathrm{avr}}$, $\ensuremath{\phi}(r)$ and the core density ${\ensuremath{\phi}}_{0}=0.74\ifmmode\pm\else\textpm\fi{}0.005$ agree with simulations.

This work concerns the use of electric field gradients to manipulate the local particle concentration in a hard-sphere-like suspension. Inside a specially designed "electric bottle," we observed our colloids to collect in the regions of lowest field strength ("negative dielectrophoresis"). This allows for the use of larger field gradients and stronger dielectrophoretic forces than in the original electric bottle design, which was based on positive dielectrophoresis [M. T. Sullivan et al., Phys. Rev. Lett. 96, 015703 (2006)]. We used confocal scanning laser microscopy to quantitatively follow the time-dependent change in the particle density and the suspension structure. Within a few days, the dielectrophoretic compression was seen to initiate a heterogeneouslike growth of large single crystals, which took place far out-of-equilibrium. The crystals had a random hexagonal close-packed structure and displayed an intriguing growth mechanism, during which the entire crystal was continuously transported, while growing both on the "high-field" and the "low-field" sides, although at different rates. After switching off the electric field, the compressed crystals were found to relax to a lower packing fraction and melt, at a much slower rate than the crystal growth. Besides revealing the particular (far out-of-equilibrium) crystal growth mechanism in these electric bottles, our observations also shed light on the role of the different particle transport processes in the cell and some of the relevant tuning parameters. This is useful for different types of experiments, for instance, focusing more on melting, homogeneous crystallization, or the glass transition.