End Of Drainage Research Articles

Relative Permeability Hysteresis and Capillary Trapping during CO2 EOR and Sequestration

Residual or capillary trapping is an important mechanism of CO2 trapping in underground porous media. Recent experimental investigation has shown that relative permeability and capillary pressure are function of saturation changing direction or hysteresis phenomenon in addition to the saturation and hysteresis leads to irreversible change in relative permeability and capillary pressure curve. In this paper, an extended review was performed on the relative permeability hysteresis models. Moreover, an experimental investigation was conducted during CO2 injection as the non–wetting phase in carbonate rocks at pressure and temperature of 10.3 MPa and 60 ℃. In this study, the effects of absolute permeability of carbonate rock samples and CO2 injection strategy on hysteresis phenomenon in the CO2 residual trapping process were investigated. During first part of experiments, CO2 relative permeability was examined during CO2 injection and brine injection at constant rate of 0.2 cc/min as drainage and imbibition process for different absolute permeability of rock samples. During second part of experiments, CO2 trapping saturation was calculated during the continuous CO2 injection and CO2 Water Alternative Gas (WAG) injection. Results of first part of experiments showed that increasing of the absolute permeability leads to increasing initial and residual CO2 saturation at the end of drainage and imbibition process, respectively. Moreover, it was concluded that increasing rock permeability results in increasing of the hysteresis effect on the CO2 relative permeability. In the second part of experiments, results revealed that CO2 WAG injection strategy has higher CO2 residual saturation in compared to CO2 continuous injection at equal pore volume of injected CO2. The findings of this paper can be applied for investigating of CO2 sequestration projects in aquifers for improvements of CO2 residual trapping and studying the performance of capillary trapping as one of the main mechanisms of CO2 trapping.

Routine monitoring with pleural manometry during therapeutic large-volume thoracentesis to prevent pleural-pressure-related complications: a multicentre, single-blind randomised controlled trial

In patients with non-expandable lung, removal of pleural fluid can result in excessively negative pleural pressure, which is associated with chest discomfort, pneumothorax, and re-expansion pulmonary oedema. Pleural manometry is widely used to safeguard against pressure-related complications during thoracentesis despite little evidence to support the approach. We investigated whether monitoring of pleural pressure with manometry during thoracentesis could protect against complications compared with assessment of symptoms alone. We did a prospective randomised single-blind trial involving patients with large pleural effusions at two academic medical centres in, Nashville, TN, and Baltimore, MD, USA. Eligible patients were adults with free-flowing effusions estimated to be at least 0·5 L who could remain seated throughout the procedure. Patients were randomly assigned 1:1 to receive thoracentesis guided by symptoms only (control) or by symptoms plus manometry at timepoints based on volume drained. The randomisation schedule was computer generated, used permuted blocks of four and six, and was stratified by participating institution. Patients, who were masked to study-group assignment, were asked to rate chest discomfort on 100 mm visual analogue scales before, during, and after drainage. In both groups drainage was discontinued before complete evacuation of pleural fluid if patients developed persistent chest discomfort, intractable cough, or other complications. In the manometry group, an additional criterion for stopping was if end-expiratory pleural pressure was lower than -20 cm H2O or declined by more than 10 cm H2O between two measurements to a value less than or equal to -10 cm H2O. The primary outcome was overall chest discomfort from before the start to after the procedure measured by patients 5 min after the end of drainage. Analysis was by modified intention to treat (ie, included all patients with any procedure or outcome data). This trial is registered with ClinicalTrials.gov, number NCT02677883. Between March 4, 2016, and Sept 8, 2017, 191 patients were screened, of whom 128 were randomly assigned treatment and 124 were included in the final analysis (62 in each group). Four patients were excluded because of manometer malfunction (n=2), inability to access effusion due to pleural tumour burden (n=1), and inability to remain seated (n=1). Groups did not differ for the primary outcome (mean difference in chest discomfort score 2·4 mm, 95% CI -5·7 to 10·5, p=0·56). Six (10%) of 62 patients in the control group had asymptomatic pneumothorax ex vacuo compared with none in the manometry group (p=0·01). No serious complications occurred in either group. Measurement of pleural pressure by manometry during large-volume thoracentesis does not alter procedure-related chest discomfort. Our findings do not support the routine use of this approach. Centurion Medical Products.

The effect of time of winter urine deposition on mineral nitrogen leaching and implications for grazed forage crops

ABSTRACTTime of urine application on mineral N (Nmin) leaching from a pumice soil was tested. Artificial urine (600 kg N ha−1) was applied in early June or late July to small plots after removing a kale/swede crop or to ryegrass/white clover. Mineral N leached in the first winter (measured by porous cups, 600 mm deep) was similar under pasture or ex-forage crop: 185 vs. 60 kg N ha−1 for June or July urine, with 170–300 kg N ha−1 remaining in the soil (0–600 mm) at the end of drainage. Additionally, 54–118 kg N ha−1 leached in the second winter. In total, later application decreased Nmin leaching by 35–40%. Application of the process inhibitor dicyandiamide increased soil Nmin levels in the post forage crop site for the early urine application but had no effect in the late-applied urine treatment. There was no significant effect on N leaching.

Experimental Investigation of Closed Porosity of Inorganic Solidified Foam Designed to Prevent Coal Fires

In order to overcome the deficiency of the existing fire control technology and control coal spontaneous combustion by sealing air leakages in coal mines, inorganic solidified foam (ISF) with high closed porosity was developed. The effect of sodium dodecyl sulfate (SDS) concentration on the porosity of the foams was investigated. The results showed that the optimized closed porosity of the solidified foam was 38.65 wt.% for an SDS concentration of approximately7.4×10-3 mol/L. Based on observations of the microstructure of the pore walls after solidification, it was inferred that an equilibrium between the hydration process and the drainage process existed. Therefore, the ISF was improved using three different systems. Gelatin can increase the viscosity of the continuous phase to form a viscoelastic film around the air cells, and the SDS + gelatin system can create a mixed surfactant layer at gas/liquid interfaces. The accelerator (AC) accelerates the hydration process and coagulation of the pore walls before the end of drainage. The mixed SDS + gelatin + AC systems produced an ISF with a total porosity of 79.89% and a closed porosity of 66.89%, which verified the proposed stabilization mechanism.

Co-sequestration of SO2 with supercritical CO2 in carbonates: An experimental study of capillary trapping, relative permeability, and capillary pressure

In this study we performed three categories of steady- and unsteady-state core-flooding experiments to investigate capillary trapping, relative permeability, and capillary pressure, in a scCO2+SO2/brine/limestone system at elevated temperature and pressure conditions, i.e., 60°C and 19.16MPa. We used a Madison limestone core sample acquired from the Rock Springs Uplift in southwest Wyoming. We carried out two sets of steady-state drainage-imbibition relative permeability experiments with different initial brine saturations to study hysteresis. We found that the final scCO2+SO2 drainage relative permeability was very low, i.e., 0.04. We also observed a rapid reduction in the scCO2-rich phase imbibition relative permeability curve, which resulted in a high residual trapping. The results showed that between 62.8% and more than 76% of the initial scCO2+SO2 at the end of drainage was trapped by capillary trapping mechanism (trapping efficiency). We found that at higher initial brine saturations, the trapping efficiency was higher. The maximum initial and residual scCO2-rich phase saturations at the end of primary drainage and imbibition were 0.525 and 0.329, respectively. Each drainage-imbibition cycle was followed by a dissolution process to re-establish Sw=1. The dissolution brine relative permeabilities for both cycles were also obtained. We characterized the scCO2+SO2/brine capillary pressure hysteresis behavior through unsteady-state primary drainage, imbibition, and secondary drainage experiments. We observed negative imbibition capillary pressure curve indicative of possible wettability alteration throughout the experiments due to contact with scCO2+SO2/brine fluid system. The trapping results were compared to those reported in literature for other carbonate core samples. We noticed slightly more residual trapping in our sample, which might be attributed to heterogeneity, different viscosity ratio, and pore-space topologies. The impact of dynamic effects, i.e., high brine flow rate imbibition tests, on trapping of the scCO2-rich phase was also explored. We performed two imbibition experiments with relatively high brine flow rates. The residual scCO2 saturation dropped to 0.291 and 0.262 at the end of the first and second imbibition tests, i.e., 11.5% and 20.4%, respectively, compared to 0.329 under capillary-dominated regime.

NT-proBNP Changes in Patients with Ascites during Large Volume Paracentesis.

Background. N-terminal probrain natriuretic peptide (NT-proBNP) is a hormone involved in the regulation of cardiovascular homeostasis. Changes in serum NT-proBNP during large volume paracentesis (LVP) in patients with ascites have never before been examined. Aims. To determine if significant changes in serum NT-proBNP occur in patients undergoing LVP and the associated clinical correlates in patients with cirrhosis. Method. A total of 45 patients with ascites were prospectively recruited. Serum NT-proBNP, biochemistry, and haemodynamics were determined at baseline and at key time points during and after paracentesis. Results. 34 patients were analysed; 19 had ascites due to cirrhosis and 15 from malignancy. In those with cirrhosis, NT-proBNP decreased by 77.3 pg/mL at 2 L of drainage and 94.3 pg/mL at the end of paracentesis, compared with an increase of 10.5 pg/mL and 77.2 pg/mL in cancer patients at the same time points (P = 0.05 and P = 0.03). Only congestive cardiac failure (CCF) was an independent predictor of significant NT-proBNP changes at the end of drainage in cirrhotic patients (P < 0.01). There were no significant changes in haemodynamics or renal biochemistry for either group. Conclusion. Significant reductions in serum NT-proBNP during LVP occur in patients with cirrhosis but not malignancy, and only comorbid CCF appeared to predict such changes.

Influence of CO2 on rock physics properties in typical reservoir rock: A CO2 flooding experiment of brine saturated sandstone in a CT-scanner

Abstract Laboratory core flooding experiment was run to investigate the joint use of electrical resistivity, ultrasonic velocities and 3D images of fluid distribution to improve current understanding of CO2 and brine behaviour during drainage and imbibition in reservoir rocks. The test specimen was cylindrical Rothbach sandstone measuring 100 mm in length and 38 mm in diameter, with a porosity of 23% and an average permeability of 400 mD. The brine saturated specimen was drained by injecting CO2 and later imbibed with brine while monitoring changes in resistivity and ultrasonic velocity measurements. Actual fluid saturation level and distribution have been mapped simultaneously using X-ray CT scan. CO2 saturation calculations based on CT values showed a steep saturation gradient at start of drainage and the gradient flattened with more CO2 injected into the sample. The ultrasonic compressional velocity (V p) measurements depicted a continuous decrease with increase in CO2 saturation while the resistivity of the sample increased proportionally with increase in CO2 saturation. A CO2 saturation of 53% was achieved at the end of drainage after injection of 20 pore volume (PV) CO2. This resulted in a decrease of V pby 7.2% while the amplitude decreased by as much as 48%. At the end of drainage, the resistivity of the sample increased to 13.9 Ω-m from full brine saturated value of 3.2 Ω-m. During imbibition, the sample was re-saturated close to 100% after 10 PV brine injection. Change in V p due to CO2 saturation level variation was relatively consistent during drainage and imbibition (no hysteresis) where as the resistivity of the sample was more affected by the flooding history resulting in hysteretic variation in resistivity. Resistivity index (RI) values did not show a consistent pattern and a single Archie’s saturation exponent (n) could not be assigned.

Experimental investigation of trapped oil clusters in a water‐wet bead pack using X‐ray microtomography

Uncertainties in the quantification of transport properties associated with multiphase flow in porous systems often make the prediction of fluid residence and migration a difficult task. Movement and trapping of immiscible fluids in permeable formations depends upon a complex combination of fluid properties, rock properties, fluid‐solid interactions, and forcing conditions. This work consists of using X‐rays and visualization techniques to map the distribution of immiscible fluids, particularly trapped oil clusters, residing in a glass bead pack subject to different flow conditions. We analyze the effect of flowing conditions on the evolution of fluid microstructures using X‐ray microtomography. Spherical glass beads (0.425–0.600 mm in diameter), a water‐wet porous medium, were packed inside a specially designed core holder. High‐resolution imaging provides detailed mapping of pore structures resulting from bead packing, and characterization of fluid microstructures formed during sequential water and oil injections. We present spatial distribution of trapped oil clusters for the entire bead pack, as well as mechanistic explanations leading to the fluid configurations observed. We also present simple statistical analyses of blob size, shape, and surface area at the end of different fluid injection cycles. Trapped oil clusters appear in sizes that range from 5.923 × 10−5 mm3 to 3.119 × 103 mm3, where 0.01–0.50 mm3 clusters are most common. About 98% of the total trapped oil at the end of drainage and imbibition cycles corresponds to blobs that are smaller than 1 mm3. It is also shown that most blobs are larger than the mean pore size (0.03 mm3). The mean oil blob size is about 5 times larger than the average pore. A typical blob extends through various interconnected pores, exhibiting elongated of ramified shapes that include multiple voids and constrictions at the same time. The mean aspect ratio of these clusters is less than 2, and the surface area to volume ratio is constant for those larger than 0.1 mm3. Experimental methods and findings presented in this paper are expected to lead to powerful calibration mechanisms for multiphase flow models.

Analysis of risk infection factors on drainage set after expander transplantation

Objective To study the risk factors related to the infection with the soft tissue expander postoperatively, such as the time of drainage. Methods Thirty consecutive patients who underwent soft tissue expander involving set negative pressure drainage tube were studied. The samples were from the skin out of the drainage tube, the drainage tube out of skin and the end of drainage after 2, 4, 6, 8 days of the operation and at the time of removing the tube. Total samples were tested for bacteriology. Results A total of samples were 170, in which 5 cases wre positive and the detection rate was 2.9%. Bacterial dectection rate in the skin out of the drainage tube and the drainage tube out of the skin during were 9% from 5 to 8days. Dection rate at the end of the drainage is 33% between 7 and 8 days. Conclusions The time of the drainage tube set is an important factor that lead to infection. If it is set more than 7 days, retrograde infection risk will increase. Key words: Drainage; Infection; Risk factors; Postoperative care

Residual amount of water in a draining curd of camembert cheese and physicochemical characteristics of the drained curd as modified by the pH at renneting, the casein concentration and the ionic strength of milk

Camembert soft cheeses were prepared from cheese milk modified using membrane tech- nologies to obtain different casein contents (27-37 g.kg -1 ) and different ionic strengths estimated from the dilution factor of milk with a lactose solution (0.6 compared to 1.0 in normal milk). Renneting was performed at pH 6.0 or 6.4. The amount of water remaining in the draining curds, expressed as the water to casein ratio, R (g .g -1 ), was calculated from the whey drainage kinetics data. A kinetics of variation of R during drainage was obtained in each of the experimental conditions and was characterised by fitting with a descriptive mathematical model involving 2 relaxation processes and 5 parameters: R (g water.g -1 casein) = R1 exp(-t/τ1) + R2 exp(-t/τ2) + R3. The R values at the end of drainage, obtained from the model for t = 1 000 min, fitted well with the water amounts determined in the drained curds by chemical analysis. The values of the equation parameters, obtained by fitting the equa- tion to experimental data, were correlated to the levels of factors which were varied in the experiments. This allowed a mean value for each parameter to be obtained, and values for the effects of factors. The amount of water remaining in drained curd at the end of drainage was dependent on the milk casein content and pH at renneting factors through a negative effect. Prediction of final values of R by cal- culation from this data was possible. However, the correlation with experimental values was low. In addition, the drained curd composition and rheological properties were determined and the effects of the factors on these curd characteristics were quantified. A positive effect of the pH at renneting on the dry matter and ash contents of drained curd was observed. Incidentally, these factors also mod- ified its rheological properties.

Characterisation of whey drainage kinetics during soft cheese manufacture in relation with the physicochemical and technological factors, pH at renneting, casein concentration and ionic strength of milk

The kinetics of whey drainage of Camembert soft cheese was studied using an instru- mented drainage device to record the pH and the weight of the whey with a variation coefficient amounting to 1.8% during the first 100 min and 0.34% at the end of drainage. Drainage data were fit with a two step equation to obtain a descriptive model of the drainage kinetics. The effect of the pH at renneting, the casein concentration and the ionic strength on the drainage kinetics was investi- gated with a 2 level experimental design. Milk was modified by a combination of ultrafiltration and dilution with a lactose solution. The pH at renneting had a negative effect on the amount of whey expelled in the early drainage (up to 100 min) and a positive one after 400 min. The effect of the casein concentration was negative on the amount of whey expelled and on the rate of drainage. The ionic strength had a slight positive effect on drainage. An equation was obtained allowing the prevision of whey drainage kinetics according to the milk composition. Calculated values fit experimental data with a correlation coefficient of r = 0.994. whey drainage / kinetics / milk composition / pH / renneting / soft cheese manufacture

Surgical treatment of chronic subdural hematoma by twist-drill craniostomy

Twenty-two consecutive cases of chronic subdural hematoma were treated successfully by twist-drill craniostomy after Tabaddor et al. and closed system drainage. The age distribution of the patients was between 44 and 83 years (mean of 64). Three of the 22 cases were female. A case of bilateral hematoma and six cases of high density hematoma (mean CT number 63.5 H.U.) were included. The drainage tube was kept in place for 3 days. Hematoma of 137 ml in average was drained on the first day, 74 ml on the second, and 22 ml on the third. The composition of the hematoma fluid drained on the first day was similar to that of peripheral blood, while that on the third day was similar to that of hygroma. In all cases, remarkable clinical amelioration was encountered soon after drainage, and no complications occurred. CT scans showed a marked reduction of the midline shift immediately after the drainage. The subdural space disappeared within a month in 14 cases and within 5 months in all except two elderly cases. In 13 cases, the subdural pressures before and at the end of drainage were measured. Among these, seven cases recorded higher pressure measurements at the end of drainage than at the beginning. An infusion test was performed in 12 cases by a bolus saline injection (4-10 ml, 1-2 ml/sec) followed by calculation of the pressure-volume index (PVI) and compliance (Co) according to Marmarou et al. Lumbar subarachnoid pressure was recorded in 10 cases. PVI ranged from 7.71 to 37.20, and Co from 0.37 to 2.30. Two cases which had high Co values (more than 3 S.D.) showed poor brain re-expansion in follow-up CT scans. In four cases, the infusion test revealed constantly higher pressure curves in the subdural space than in the subarachnoid. This means that a difference in tightness across the tentorium exists in patients with chronic subdural hematoma and that this may contribute to some extent to the onset of clinical symptoms and signs. This method has certain advantages, i.e. less surgical insult, freedom from tension pneumocephalus, and high precision in investigations of intracranial conditions under chronic brain compression in man. Even in two cases of poor brain re-expansion, this method was safely and effectively performed.