Comparison Of Pressure Measurements Research Articles

Interference Testing to Characterize the Injection Behaviour of a 20-Acre Pattern in the Court Field

Abstract In the Court Field, the middle Bakken Sand Pool has been operated as a heavy oil waterflood for over 15 years. However, unrecovered oil volumes in the pool remain attractive for improved recovery schemes. Recently, the Court Middle Bakken Reservoir model was updated to evaluate the potential for downspacing and waterflood optimization of the reservoir. The potential for 20-acre downspacing for both infill drilling and additional water injection was identified by this study. As part of the additional development program, an injector producer well pair was drilled to create a new injection pattern with reduced inter-well spacing. Reservoir pressures, water saturation and effective permeability to water in the pattern were determined by RFT and log data. Pattern characterization was complemented by an interference test, including all the wells in the pattern. Analytical and numerical tools were used in the test design. The most comprehensive results were obtained by local grid refinement of the pattern area in the full field simulation model. Unavoidable interference with a neighboring pattern during the test was predicted. In order to account for this effect, it was decided to run the test with the new injector active intermittently. The complete test design and analysis of the results are described. In addition, a comparison of pressure measurements by downhole gauge and acoustic well sounder are presented. Introduction The Court Field, located in west central Saskatchewan, produces 17 ºAPI heavy crude from the Middle Bakken Formation, using vertical wells and a waterflood recovery scheme. The Court Bakken Sand was discovered in November 1981. The Court Bakken Sand Voluntary Unit No. 1 was formed in 1988 and waterflood commenced with only 2% of OOIP produced. There are 39 producing oil wells and 21 water injection wells currently in operation within the main pool. The current recovery factor is approximately 20%, with some wells producing up to 30m3/d oil. Recently, Majcher et al.(1) presented a geological and engineering overview of the reservoir. The Middle Bakken Formation was deposited as NE-SW trending sand ridges. The pool has undergone significant collapse of the Torquay Formation with the subsequent creation of extensive post-depositional sinkholes within the Bakken. This structural deformation interrupts the lateral continuity of the sand ridge and its characterization is the most challenging to further field development and effective waterflood management. Another important Bakken heterogeneity is the change in well log signature that represents the variation in facies at the ridge edges(2). This facies distribution within the Middle Bakken correlates with the waterflood response. Majcher et al.(1) identified the potential for infill drilling of producers and injectors near the edges of the pool. An injector-producer pair was recently drilled in Section 36-033-28W3M on 20-acre spacing. An interference test with four wells was conducted to investigate how the heterogeneities described above affect the waterflood performance of the newly configured pattern.

The dependence of the superconducting transition temperatureTc on the quasi-two-dimensional carrier concentration in the organic superconductorκ-(BEDT-TTF)2Cu(SCN)2 (BEDT-TTF ⋡ bis(ethylene-dithio)tetrathiafulvalene)

In this paper we discuss the effect of the quasi-two-dimensional carrier concentration,nQ2D on the superconducting transition temperature,Tc, of the organicsuperconductor κ-(BEDT-TTF)2Cu(SCN)2.Recent ac susceptibility as well as magnetotransport measurements on the organic superconductorκ-(BEDT-TTF)2Cu(SCN)2 under pressure with different pressure media are compared. The exact results of the individualpressure experiments are pressure media dependent, thus making the experimentallydetermined pressure an unsuitable parameter for describing the physical properties ofκ-(BEDT-TTF)2Cu(SCN)2. The pressure media dependence is thought to originate from the difference in thermalcontraction between the isotropic pressure medium and the highly anisotropic and very softsample. However, comparison of pressure measurements with different media reveals a pressuremedium independent correlation between the superconducting transition temperature,Tc, and thesize of the quasi-two-dimensional Fermi surface pocket and thus the quasi-two-dimensional carrier densityin κ-(BEDT-TTF)2Cu(SCN)2. The observed pressure-induced increase in the quasi-two-dimensional carrier density canbe interpreted as a transfer of carriers from quasi-one-dimensional Fermi surface sections,reminiscent of a mechanism in cuprate superconductors, where pressure is known totransfer carriers from the insulating charge reservoir layers into the conducting cupratesheets. In further analogy with the cuprate superconductors, it is seen that the highestTc is achieved at carrier concentrations of , which is very similar to the value found consistently for optimal doping in cupratesuperconductors.

Comparative magnetotransport andTc measurementson κ-(BEDT-TTF)2Cu(SCN)2 under pressure

We compare magnetotransport measurements under pressure on the organic superconductorκ-(BEDT-TTF)2Cu(SCN)2 (BEDT- (ethylene-dithio)tetrathiafulvalene) with different pressure media and discover thatthe results are pressure media dependent. This pressure medium dependence isthought to originate from the difference in thermal contraction between the verysoft and highly anisotropic sample and the isotropically contracting, but solidpressure medium, thus resulting in non-hydrostatic pressure on the sample. However,comparison of pressure measurements with different media reveals a pressure mediumindependent correlation between the superconducting transition temperature,Tc, and thesize of the quasi-two-dimensional Fermi surface pocket and thus the quasi-two-dimensional carrier densityin κ-(BEDT-TTF)2Cu(SCN)2. The observed pressure-induced increase in the quasi-two-dimensional carrier density canbe interpreted as a transfer of carriers from quasi-one-dimensional Fermi surface sections,reminiscent of a mechanism in cuprate superconductors, where pressure is known totransfer carriers from the insulating charge reservoir layers into the conducting cupratesheets.

Comparison of pressure measurement, dobutamine contrast stress echocardiography and SPECT for the evaluation of intermediate coronary stenoses. The COMPRESS trial

DSE and SPECT are two well-established methods to non-invasively investigate the functional significance of coronary artery stenoses in patients with coronary artery disease. The measurement of Fractional Flow Reserve has emerged a new invasive reference standard for lesion specific quantification of coronary artery stenoses. The objective of our prospective study was to compare sensitivity and specificity of Dobutamine Stress Echocardiography (DSE) and Single Photon Emission Computer tomography (SPECT) with the pressure derived Fractional Flow Reserve (FFR) for the identification of hemodynamic relevant coronary lesions in patients with predominately coronary multivessel disease and angiographically intermediate stenoses. Inclusion criteria were a coronary lesion of 50-75% diameter stenosis by visual assessment in patients with known or suspected CAD. SPECT, DSE and FFR testing was performed within one week of coronary angiography. The study comprised 48 consecutive symptomatic patients. In 41 cases, a coronary multivessel disease was present. Mean FFR was 0.80 +/- 0.13 (0.41-1.0). Overall sensitivity of DSE and SPECT was 67% and 69% whereas specificity reached 77% and 87%. However, sensitivity was significantly reduced if the target lesion was located distally. DSE showed poor results if the lesions were located in the circumflex artery or if a history of prior myocardial infarctions was present. DSE and SPECT are both useful methods for the non-invasive assessment of coronary artery disease. DSE showed reasonable combination of sensitivity and specificity even in patients with multivessel disease. Although use of noninvasive stress tests is only limited in patients with prior myocardial infarctions and invasive stress testing should be preferred in these patients.

Adsorption of polyacrylic acid on self-assembled monolayers investigated by single-molecule force spectroscopy

Single-molecule force spectroscopy was used to study the adsorption and desorption processes of individual polyacrylic acid (PAA) chains from self-assembled monolayers (SAMs) with different terminal groups (CH3, OH, COOH). PAA was grafted to the tip of an AFM cantilever and all measurements were recorded with the same tip. For the OH- and the COOH-SAM, the desorption force was found to be independent of the salt concentration for NaCl, as well as for CaSO4. On CH3-SAM, a repulsive electrostatic interaction was found with NaCl in solution whereas a slightly attractive electrostatic interaction occurred with CaSO4 in solution. On the OH- and the COOH-terminated SAM, the non-electrostatic contributions to the desorption forces are of comparable magnitude (∼50–65 pN) whereas the non-electrostatic contribution for the CH3-terminated SAM is significantly higher (∼80–90 pN). Additional experimental findings concerning the length, the total number of adsorption events and the number of multiple polymer strands adsorbed in parallel, support the assumption that this difference in adsorption force is due to a different quality of the solvent for the polyacrylic acid chains at the SAM–water interface. Comparative surface pressure measurements at the air–water interface revealed a surface energy for polyacrylic acid of 30 mJ m2 which would correspond to a force contribution of ∼10 pN to the desorption force. This is in good agreement with the experimental results on hydrophobic SAMs. For further characterization of the surfaces the pH was varied from 3 to 11 at constant salt concentration (for a NaCl concentration of 100 mM and a CaSO4 concentration of 5 mM, respectively). In the presence of NaCl, the desorption force was found to be independent of the pH for all three substrates. For CaSO4, the desorption force was pH-independent for the OH- and the CH3-SAM. In the case of the COOH-SAM, a jump from 60 to 90 pN was recorded at pH 8, which we attribute to the formation of salt bridges between the polyacrylic acid chain and the COOH-SAM at higher pH.

Freeze‐drying using vacuum‐induced surface freezing

A method of freezing during freeze‐drying, which avoids undercooling of a solution and allows growth of large, dendritic ice crystals, was investigated. Aqueous solutions of mannitol, sucrose, or glycine were placed under a chamber vacuum of approximately 1 mbar at a shelf temperature of + 10°C. Under these conditions, the solutions exhibit surface freezing to form an ice layer of approximately 1–3 mm thickness. On releasing the vacuum and lowering the shelf temperature to below the freezing point of the ice in the solution, crystal growth occurs to yield large, chimney‐like ice crystals. The duration of primary drying of a frozen cake—as measured by using inverse comparative pressure measurement—was up to 20% shorter than when using a “moderate” freezing procedure (2 K shelf temperature per min). With mannitol, however, the residual moisture content of the final dried product was higher than with moderate freezing, and with sucrose and glycine there was no difference. These findings are related to the structures of the dried cakes formed during freezing, as examined by light microscopy and wide‐angle X‐ray diffraction. The introduction of an annealing step (4 h at a shelf temperature slightly above the onset melting point of the ice in the frozen cake) combined with the vacuum‐induced surface freezing procedure maintains the rapid primary drying and produces a low residual moisture (0.2%) for the freeze‐dried mannitol solution.

Indirect and Direct Simultaneous, Comparative Blood Pressure Measurements with the Bosotron 2® Device

Testing the accuracy of the automatic blood pressure measuring device Bosotron2®, we performed simultaneous, same–arm, comparative blood pressure measurements with three instruments (A, B, and C) of the device and by auscultation in the antecubital fossa by a trained observer in 24 volunteers each. The volunteers were evenly matched for age, sex, and blood pressure level. The mean systolic differences and their standard deviations (24 subjects each, n = 288 single measurements) were –1.32±3.8 mm Hg for instrument A, –0.99±3.9 mm Hg for instrument B, and –1.12±5.0 mm Hg for instrument C. The corresponding values for the diastolic differences were –2.71±4.4, –3.46±4.3, and –2.72±3.9 mm Hg, respectively. Combining the results for the three instruments, the comparison yielded a good accuracy (mean difference) and sufficient repeatability of the differences (standard deviation) for the systolic and diastolic blood pressures (systolic –1.14±4.3 mm Hg; diastolic –2.96±4.2 mm Hg). In addition to the British Hypertension Society protocol, in 33 patients with coronary artery disease the measurements using the three Bosotron 2 devices were compared with measurements within the aortic arch. The mean systolic/diastolic differences (±SD) were +1.45±4.3 and +7.27±4.7 mm Hg for instrument A, +4.70±12.8 and +1.73±7.4 mm Hg for instrument B, and –3.74±8.0 and +5.61±2.6 mm Hg for instrument C. Combining the results of the three instruments, the blood pressure was determined to be only slightly higher (systolic +1.74±9.6 mm Hg; diastolic +4.87±5.6 mm Hg) by the Bosotron 2® device as compared with the aortic arch pressure. The Bosotron 2® device seems to be suitable for clinical use and for monitoring blood pressure during clinical–pharmacological studies.

Final report: Comparison of pressure measurements

Final report: Comparison of pressure measurements

Bilateral Comparative Pressure Measurements of the LNE and the PTB Using 10 cm2 Piston-Cylinder Assemblies

The effective areas of two transfer standards were determined from cross-floating experiments. It was possible to reproduce the ratio of the effective areas of the primary standards using data obtained for the transfer standards within 1,6 × 10-6, but for the absolute effective area values of the transfer standards, relative differences up to 11,6 × 10-6 were measured. Additional dimensional measurements were performed to discover the reason for the disagreement. It seems likely that this is due to problems in performing sufficiently accurate dimensional measurements.

Further full-scale and model pressure measurements on a cantilever grandstand

Extending the work reported in a previous paper (L.W.A. Apperley and N. Pitsis, J. Wind Eng. Ind. Aerodyn., 23 (1986) 99–111), further comparative pressure measurements have been undertaken full scale and also in a wind tunnel on a 1:150 scale model of the cantilever roof of a grandstand at the Cronulla Sutherland Leagues Club in Sydney (Caltex Oval). Measurements were made at distances of 50 cm, 150 cm and 250 cm from the roof edge, where separation is expected. Discrepancies between model and full scale occurred close to the edge, but close agreement was obtained for distances greater than 100 cm from the edge.

International Comparison of Pressure Balance Standards over the 1 MPa to 10 MPa Range

A synopsis is given of the results of comparative pressure measurements performed by the Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, in cooperation with the following institutions: Bureau National de Métrologie (BNM), Paris, Istituto di Metrologia "G Colonnetti" (IMGC), Turin, National Bureau of Standards (NBS), Washington, National Physical Laboratory (NPL), Teddington. Reference is made to the results of intercomparison experiments of the BNM together with the institute of the Gosstandart (VNIIM), Moscow.

Nucleid-angiographic calculations of left ventricular end-diastolic pressure, pulmonary capillary pressure and diastolic pulmonary pressure (author's transl)

Proper of cardiac nucleid-angiography provides parameters which are comparable to those obtained by invasive procedures. Although various methods have been devised for determining left ventricular ejection rate and the geometric analysis of the left ventricle by isotope techniques (Adam 2-5), Ashburn (6, 7), Breuel (11, 12), Strauss/Bill, Strauss/Pitt (65, 66, 67), only a few comparative intra-cavitary pressure measurements are available. Of these, the method developed by de Vernejoul (73 to 76) is of particular importance for measurements during the bolus phase because of the large number of cases studied by simultaneous catheterisation (670 patients). The value of de Vernejoul's formula was confirmed by a study of 350 of our own cases. The disadvantage of the method lies in its susceptibility to variations in the bolus front. We have therefore attempted for some time to obtain pressure measurements by a pooling procedure.

Comparison of Pressure Measurements in the Lower Urinary and Lower Fecal Pathways

The bladder and rectal ampullae have similar but not identical innervation from the spinal cord S2 to S4. A comparison of the functional behavior of the bladder and rectal ampullae was done with a cystometrogram and an ampullometrogram. The behavior of the urethral and anal sphincters was compared with electromyography and pressure profiles. In 20 patients there was a close relationship between the functional behavior of the lower urinary and lower fecal pathways.

Normocapnic anaesthesia with trichloroethylene for intraocular surgery

Measurements of intraocular pressure (IOP) by applanation tonometry in twelve patients undergoing lens extraction showed that a normocapnic anaesthetic technique using 0.4% trichloroethylene with controlled ventilation of the lungs (IPPV) with large tidal volumes (14 ml/kg) reduced IOP by 13--20%. There was only a small reduction in arterial pressure. Normocapnia was easy to achieve by use of the single-limb co-axial Penlon (Bain type) anaesthetic breathing circuit in conjunction with an electrically-driven, small and inexpensive lung ventilator. The anaesthetic technique described using trichloroethylene is suitable for lens extraction surgery when it is desired to avoid a halothane anaesthetic for any reason.

Vergleichende Tonometrie mit lageunabhängigen Handapplanationstonometern

A study of comparative intraocular pressure measurements was made using the hand-held applanation tonometers of Perkins and Draeger in the sitting and lying patient. A series of 100 patients was investigated by two observers taking the pressures with both tonometers under blind conditions. The statistical evaluation of the data revealed an average pressure increment when lying down of 2.5 to 3 mm Hg for both observers and both tonometers. This postural response is fully reversible when getting up and an overshoot-phenomenon statistically significant is noted. The pressure increment when lying down is not related to initial pressure level and there is no clear relationship to the age of the patients tested. Interobserver variation as well as variations of both tonometers are evaluated. The effect of repeated tonometry in this study is considered. Some aspects of position influence on the intraocular pressure are discussed.

Comparative Intraocular Pressure Measurements with the Pneumatonograph and Goldmann Tonometer

Comparative intraocular pressure measurements made with the pneumatonograph and the Goldmann tonometer showed close agreement with a statistically higher mean pressure when using the pneumatonograph. Significant changes in mean pressure differences between the two instruments were seen upon changing the pneumatonograph calibration and with change in the order of testing (which instrument was used initially). However, transient biologic changes in an individual eye producing minute-to-minute fluctuations in intraocular pressure may be equal to or larger than differences in measurement between instruments.

Quantitative Studies of Microcirculatory Structure and Function

A modified version of the Wiederhielm electronic servo system for micropressure recordings was used to establish the details of the pressure drop across successive segments of the microcirculation from arterioles (150µ) to venules (200µ) in the mesentery of the cat; most of the readings were made in vessels less than 25jz in diameter. Micropressures correlated with central pressure only in arterial vessels larger than 50µ. Frequencydistribution plots of micropressures showed a wider spread in the vessels that were 50-1Oµ in diameter than they did in capillary vessels that were less than 20µ in diameter.Therefore, it appears that classification of vessels on the basis of diameter, which is at present the only practical way of comparing pressure measurements in presumably identical segments of a continuously branching system, is not adequate and makes statistical analysis difficult. In the present study, micropressures remained pulsatile throughout the bed, although the pulse pressure could be narrowed to 2-4 mm Hg in the capillaries. Simultaneous measurement of pressure in two vessels showed that the greatest pressure drop occurred in the region where arterioles (40-50)u) distributed numerous precapillary branches (10-15/x); in this region arteriolar pressures were reduced from a level of 45-65 mm Hg to about 30-35 mm Hg. These data suggest that application of the resistance term for Poiseuille flow in the microcirculation should take into account the relative sizes of the parent vessel and the branch, the entry dimensions into the branch and the length of the neck or junctional segment. Evidence found in this investigation indicated that precapillary branching configurations were self-regulatory. A small number of low-resistance, shunt pathways between arterioles and venules were regularly present, as shown by the extremely small pressure drop in 15-18% of the vessels. The data indicate that much more caution is needed in interpretation of pressure-related phenomena in the microcirculation because of their strong dependence on the anatomical and physical features characteristic of individual tissues.

Aspects of excretory ultrafiltration in the bivalved molluscs

1. 1. Comparative osmotic pressure measurements of the blood and the pericardial fluid in five species of bivalves revealed an osmotic pressure gradient from the pericardial fluid toward the blood. 2. 2. Measurements of the ventricular hydrostatic pressures in the same five species of bivalves indicated that the systolic pressure of the ventricle is smaller than the osmotic pressure gradient. 3. 3. Therefore, ultrafiltration cannot take place across the ventricle into the pericardial cavity.

Comparative blood pressure measurements by palpation and sound methods under conditions of a dynamic functional test of the cardiovascular system

If you measure the blood pressure on the brachial artery by the method. Korotkov and palpation on radiation according to Riva-Rocci, how this was proved by a number of works from the clinic of prof. MV Yanovsky, the figures for the maximum pressure for both methods, as a rule, do not coincide with each other. Prof. N.A. Kurshakov) it was found that normally the appearance of a pulse on the radial artery usually coincides with the onset of the noise phase according to Korotkov. In the same cases of coincidence of the above phenomena, the beginning of the noise phase corresponds to the beginning of the curve recording on the sphygmogram, and the resumption of capillary current after the preliminary cessation of circulation by the sleeve of the cuff.