Numerical Simulation of a Two-Phase Flow with Low Permeability anda Start-Up Pressure Gradient

A new numerical model for low-permeability reservoirs is developed.The model incorporates the nonlinear characteristics of oil-water two-phase flows while taking into account the initiation pressure gradient.Related numerical solutions are obtained using a finite difference method.The correctness of the method is demonstrated using a two-dimensional inhomogeneous low permeability example.Then,the differences in the cumulative oil and water production are investigated for different starting water saturations.It is shown that when the initial water saturation grows,the water content of the block continues to rise and the cumulative oil production gradually decreases.

Impacts of proppant distribution on development of tight oil reservoirs with threshold pressure gradient

Field evidence indicates that proppant distribution and threshold pressure gradient have great impacts on well productivity.Aiming at the development of unconventional oil reservoirs in Triassic Chang-7 Unit,Ordos Basin of China,we presented an integrated workflow to investigate how(1)proppant placement in induced fracture and(2)non-linear flow in reservoir matrix would affect well productivity and fluid flow in the reservoir.Compared with our research before(Yue et al.,2020),here we extended this study into the development of multi-stage fractured horizontal wells(MFHWs)with large-scale complicated fracture geometry.The integrated workflow is based on the finite element method and consists of simulation models for proppant-laden fluid flow,fracture flow,and non-linear seepage flow,respectively.Simulation results indicate that the distribution of proppant inside the induced cracks significantly affects the productivity of the MFHW.When we assign an idealized proppant distribution instead of the real distribution,there will be an overestimation of 44.98%in daily oil rate and 30.63%in cumulative oil production after continuous development of 1000 days.Besides,threshold pressure gradient(TPG)also significantly affects the well performance in tight oil reservoirs.If we simply apply linear Darcy’s law to the reservoir matrix,the overall cumulative oil production can be overrated by 77%after 1000 days of development.In general,this research provides new insights into the development of tight oil reservoirs with TPG and meanwhile reveals the significance of proppant distribution and non-linear fluid flow in the production scenario design.

Prediction of pressure gradient and hold-up in horizontal liquid-liquid pipe flow

This paper aims to propose correlations to predict pressure gradient,friction factor and fluid phase hold-up in liquid-liquid horizontal pipe flow.To develop the correlations,experiments are conducted using high viscous oils(202 and 630 mPa⋅s)in a steel pipe of length 11.25 m and length-to-diameter ratio of 708.In addition,the experimental data from the literature comprising wide range of flow and fluid properties is analyzed.For the analysis,the liquid-liquid pipe flow data is categorized into two as:stratified and dispersed.The existing friction factor correlations are modified to incorporate the effects of viscosity of the oil phase,interfacial curvature(contact/wetting angle-in lieu of material of the pipe)and fluid phase fraction.In the two-fluid model of stratified flow,the wall stress and interfacial stress correlations are substituted with superficial velocities of fluids and superficial Reynolds numbers of fluid phases replacing fluid phase velocities and fluid Reynolds numbers.Similarly,for dispersed flow,an effective Reynolds number is described as the sum of superficial Reynolds number of oil and water phases.Substituting the generally employed mean or mixture Reynolds number with the effective Reynolds number into the existing single-phase turbulent flow friction factor correlation,an effective friction factor for oil-water flow is proposed.Employing the proposed correlations,the pressure gradient across the oil-water flow and hold-up volume fraction are predicted with significant reduction in error compared with that of conventionally employed correlations.The average error and standard deviation values of−7.06%,20.72%and 0.31%,18.79%are found for stratified flow and dispersed flow respectively.

Pre-transjugular-intrahepatic-portosystemic-shunt measurement of hepatic venous pressure gradient and its clinical application: A comparison study

BACKGROUND It is controversial whether transjugular intrahepatic portosystemic shunt(TIPS)placement can improve long-term survival.AIM To assess whether TIPS placement improves survival in patients with hepaticvenous-pressure-gradient(HVPG)≥16 mmHg,based on HVPG-related risk stratification.METHODS Consecutive variceal bleeding patients treated with endoscopic therapy+nonselectiveβ-blockers(NSBBs)or covered TIPS placement were retrospectively enrolled between January 2013 and December 2019.HVPG measurements were performed before therapy.The primary outcome was transplant-free survival;secondary endpoints were rebleeding and overt hepatic ence-phalopathy(OHE).RESULTS A total of 184 patients were analyzed(mean age,55.27 years±13.86,107 males;102 in the EVL+NSBB group,82 in the covered TIPS group).Based on the HVPG guided risk stratification,70 patients had HVPG<16 mmHg,and 114 patients had HVPG≥16 mmHg.The median follow-up time of the cohort was 49.5 mo.There was no significant difference in transplant-free survival between the two treatment groups overall(hazard ratio[HR],0.61;95%confidence interval[CI]:0.35-1.05;P=0.07).In the high-HVPG tier,transplant-free survival was higher in the TIPS group(HR,0.44;95%CI:0.23-0.85;P=0.004).In the low-HVPG tier,transplantfree survival after the two treatments was similar(HR,0.86;95%CI:0.33-0.23;P=0.74).Covered TIPS placement decreased the rate of rebleeding independent of the HVPG tier(P<0.001).The difference in OHE between the two groups was not statistically significant(P=0.09;P=0.48).CONCLUSION TIPS placement can effectively improve transplant-free survival when the HVPG is greater than 16 mmHg.

Hepatic venous pressure gradient: Inaccurately estimates portal venous pressure gradient in alcoholic cirrhosis and portal hypertension

BACKGROUND Portal hypertension(PHT)in patients with alcoholic cirrhosis causes a range of clinical symptoms,including gastroesophageal varices and ascites.The hepatic venous pressure gradient(HVPG),which is easier to measure,has replaced the portal venous pressure gradient(PPG)as the gold standard for diagnosing PHT in clinical practice.Therefore,attention should be paid to the correlation between HVPG and PPG.METHODS Between January 2017 and June 2020,134 patients with alcoholic cirrhosis and PHT who met the inclusion criteria underwent various pressure measurements during transjugular intrahepatic portosystemic shunt procedures.Correlations were assessed using Pearson’s correlation coefficient to estimate the correlation coefficient(r)and determination coefficient(R^(2)).Bland-Altman plots were constructed to further analyze the agreement between the measurements.Disagreements were analyzed using paired t tests,and P values<0.05 were considered statistically significant.RESULTS In this study,the correlation coefficient(r)and determination coefficient(R2)between HVPG and PPG were 0.201 and 0.040,respectively(P=0.020).In the 108 patients with no collateral branch,the average wedged hepatic venous pressure was lower than the average portal venous pressure(30.65±8.17 vs.33.25±6.60 mmHg,P=0.002).Hepatic collaterals were identified in 26 cases with balloon occlusion hepatic venography(19.4%),while the average PPG was significantly higher than the average HVPG(25.94±7.42 mmHg vs 9.86±7.44 mmHg;P<0.001).The differences between HVPG and PPG<5 mmHg in the collateral vs no collateral branch groups were three cases(11.54%)and 44 cases(40.74%),respectively.CONCLUSION In most patients,HVPG cannot accurately represent PPG.The formation of hepatic collaterals is a vital reason for the strong underestimation of HVPG.

Computed tomography perfusion in differentiating portal hypertension: A correlation study with hepatic venous pressure gradient

BACKGROUND Hepatic venous pressure gradient(HVPG)is the gold standard for diagnosis of portal hypertension(PH),invasiveness and potential risks in the process of measurement limited its widespread use.AIM To investigate the correlation of computed tomography(CT)perfusion parameters with HVPG in PH,and quantitatively assess the blood supply changes in liver and spleen parenchyma before and after transjugular intrahepatic portosystemic shunt(TIPS).METHODS Twenty-four PH related gastrointestinal bleeding patients were recruited in this study,and all patients were performed perfusion CT before and after TIPS surgery within 2 wk.Quantitative parameters of CT perfusion,including liver blood volume(LBV),liver blood flow(LBF),hepatic arterial fraction(HAF),spleen blood volume(SBV)and spleen blood flow(SBF),were measured and compared before and after TIPS,and the quantitative parameters between clinically significant PH(CSPH)and non-CSPH(NCSPH)group were also compared.Then the correlation of CT perfusion parameters with HVPG were analyzed,with statistical significance as P<0.05.RESULTS For all 24 PH patients after TIPS,CT perfusion parameters demonstrated decreased LBV, increased HAF, SBV and SBF, with no statistical difference in LBF. Compared withNCSPH, CSPH showed higher HAF, with no difference in other CT perfusion parameters. HAFbefore TIPS showed positive correlation with HVPG (r = 0.530, P = 0.008), while no correlation wasfound in other CT perfusion parameters with HVPG and Child-Pugh scores.CONCLUSIONHAF, an index of CT perfusion, was positive correlation with HVPG, and higher in CSPH thanNCSPH before TIPS. While increased HAF, SBF and SBV, and decreased LBV, were found afterTIPS, which accommodates a potential non-invasive imaging tool for evaluation of PH.

Effect of quadratic pressure gradient term on a one-dimensional moving boundary problem based on modified Darcy's law

A relatively high formation pressure gradient can exist in seepage flow in low-permeable porous media with a threshold pressure gradient, and a significant error may then be caused in the model computation by neglecting the quadratic pressure gradient term in the governing equations. Based on these concerns, in consideration of the quadratic pressure gradient term, a basic moving boundary model is constructed for a one-dimensional seepage flow problem with a threshold pressure gradient. Owing to a strong nonlinearity and the existing moving boundary in the mathematical model, a corresponding numerical solution method is presented. First, a spatial coordinate transformation method is adopted in order to transform the system of partial differential equa- tions with moving boundary conditions into a closed system with fixed boundary conditions; then the solution can be sta- bly numerically obtained by a fully implicit finite-difference method. The validity of the numerical method is verified by a published exact analytical solution. Furthermore, to compare with Darcy＇s flow problem, the exact analytical solution for the case of Darcy＇s flow considering the quadratic pressure gradient term is also derived by an inverse Laplace transform. A comparison of these model solutions leads to the conclu- sion that such moving boundary problems must incorporate the quadratic pressure gradient term in their governing equa- tions; the sensitive effects of the quadratic pressure gradient term tend to diminish, with the dimensionless threshold pres- sure gradient increasing for the one-dimensional problem.

Cirrhosis and portal hypertension: The importance of risk stratification, the role of hepatic venous pressure gradient measurement

Portal hypertension is the main prognostic factor in cirrhosis. The recent emergence of potent antiviral drugs and new algorithm of treatment for the management of complications due to portal hypertension have sensibly changed our perception of cirrhosis that can be now considered as a multistage liver disease whose mortality risk can be reduced by a tailored approachfor any stage of risk. Experts recommend to move toward a pathophysiological classification of cirrhosis that considers both structural and functional changes. The hepatic venous pressure gradient HVPG, is the reference gold standard to estimate the severity of portal hypertension in cirrhosis. It correlates with both structural and functional changes that occur in cirrhosis and carries valuable prognostic information to stratify the mortality risk. This article provides a general overview of the pathophysiology and natural course of cirrhosis and portal hypertension. We propose a simplified classification of cirrhosis based on low, intermediate and high mortality stage. The prognostic information provided by HVPG is presented according to each stage. A comparison with prognostic models based on clinical and endoscopic variables is discussed in order to evidence the additional contribute given by HVPG on top of other clinical and instrumental variables widely used in clinical practice.

Comparison of hepatic venous pressure gradient and endoscopic grading of esophageal varices

AIM: To determine the correlation between the hepatic venous pressure gradient and the endoscopic grade of esophageal varices.METHODS: From September 2009 to March 2013, a total of 176 measurements of hepatic venous pressure gradient (HVPG) were done in 146 patients. Each transjugular HVPG was measured twice, first using an end whole catheter (EH-HVPG), and then using a balloon catheter (B-HVPG). The HVPG was compared with the endoscopic grade of esophageal varices (according to the general rules for recording endoscopic findings of esophagogastric varices), which was recorded within a month of the measurement of HVPG.RESULTS: The study included 110 men and 36 women, with a mean age of 56.1 years (range, 43-76 years). The technical success rate of the pressure measurements was 100% and there were no complication related to the procedures. Mean HVPG was 15.3 mmHg as measured using the end hole catheter method and 16.5 mmHg as measured using the balloon catheter method. Mean HVPG (both EH-HVPG and B-HVPG) was not significantly different among patients with different characteristics, including sex and comorbid factors, except for cases with hepatocellular carcinoma (B-HVPG, P = 0.01; EH-HVPG, P = 0.02). Portal hypertension (&#x0003e; 12 mmHg HVPG) occurred in 66% of patients according to EH-HVPG and 83% of patients according to B-HVGP, and significantly correlated with Child&#x02019;s status (B-HVPG, P &#x0003c; 0.000; EH-HVGP, P &#x0003c; 0.000) and esophageal varies observed upon endoscopy (EH-HVGP, P = 0.003; B-HVGP, P = 0.006). One hundred and thirty-five endoscopies were performed, of which 15 showed normal findings, 27 showed grade 1 endoscopic esophageal varices, 49 showed grade 2 varices, and 44 showed grade 3 varices. When comparing endoscopic esophageal variceal grades and HVPG using univariate analysis, the P value was 0.004 for EH-HVPG and 0.002 for B-HVPG.CONCLUSION: Both EH-HVPG and B-HVPG showed a positive correlation with the endoscopic grade of esophageal varices, with B-HVPG showing a stronger correlation than EH-HVPG.

Hepatic venous pressure gradient measurement before TIPS for acute variceal bleeding

Hepatic venous pressure gradient(HVPG)is an independent predictor of variceal rebleeding in patients with cirrhosis.After pharmacological and/or endoscopic therapy,the use of a transjugular intrahepatic portosystemic shunt(TIPS)may be necessary in HVPG non-responders,but not in responders.Thus,HVPG measurement may be incorporated into the treatment algorithm for acute variceal bleeding,which further identifies the candidates that should undergo early insertion of TIPS or maintain the traditional pharmacological and/or endoscopic therapy.The potential benefits are to reduce the cost and prevent TIPS-related complications.

Research on the nonlinear spherical percolation model with quadratic pressure gradient and its percolation characteristics

For bottom water reservoir and the reservoir with a thick oil formation, there exists partial penetration completion well and when the well products the oil flow in the porous media takes on spherical percolation. The nonlinear spheri-cal flow equation with the quadratic gradient term is deduced in detail based on the mass conservation principle, and then it is found that the linear percolation is the approximation and simplification of nonlinear percolation. The nonlinear spherical percolation physical and mathematical model under different external boundaries is established, considering the ef-fect of wellbore storage. By variable substitu-tion, the flow equation is linearized, then the Laplace space analytic solution under different external boundaries is obtained and the real space solution is also gotten by use of the nu-merical inversion, so the pressure and the pressure derivative bi-logarithmic nonlinear spherical percolation type curves are drawn up at last. The characteristics of the nonlinear spherical percolation are analyzed, and it is found that the new nonlinear percolation type curves are evidently different from linear per-colation type curves in shape and characteris-tics, the pressure curve and pressure derivative curve of nonlinear percolation deviate from those of linear percolation. The theoretical off-set of the pressure and the pressure derivative between the linear and the nonlinear solution are analyzed, and it is also found that the in-fluence of the quadratic pressure gradient is very distinct, especially for the low permeabil-ity and heavy oil reservoirs. The influence of the non-linear term upon the spreading of pressure is very distinct on the process of percolation, and the nonlinear percolation law stands for the actual oil percolation law in res-ervoir, therefore the research on nonlinear per-colation theory should be strengthened and reinforced.

Numerical investigation of a coupled moving boundary model of radial flow in low-permeable stress-sensitive reservoir with threshold pressure gradient

The threshold pressure gradient and formation stress-sensitive effect as the two prominent physical phenomena in the development of a low-permeable reservoir are both considered here for building a new coupled moving boundary model of radial flow in porous medium. Moreover, the wellbore storage and skin effect are both incorporated into the inner boundary conditions in the model. It is known that the new coupled moving boundary model has strong nonlinearity. A coordinate transformation based fully implicit finite difference method is adopted to obtain its numerical solutions. The involved coordinate transformation can equivalently transform the dynamic flow region for the moving boundary model into a fixed region as a unit circle, which is very convenient for the model computation by the finite difference method on fixed spatial grids. By comparing the numerical solution obtained from other different numerical method in the existing literature, its validity can be verified. Eventually, the effects of permeability modulus, threshold pressure gradient, wellbore storage coefficient, and skin factor on the transient wellbore pressure, the derivative, and the formation pressure distribution are analyzed respectively.

Correlation of pressure gradient in three hepatic veins with portal pressure gradient

BACKGROUND The liver is one of the most important organs in the human body,with functions such as detoxification,digestion,and blood coagulation.In terms of vascular anatomy,the liver is divided into the left and the right liver by the main portal vein,and there are three hepatic efferent veins(right,middle,and left)and two portal branches.Patients with impaired liver function have increased intrahepatic vascular resistance and splanchnic vasodilation,which may lead to an increase in the portal pressure gradient(PPG)and cause portal hypertension(PHT).In order to measure the increased pressure gradient of portal vein,the hepatic venous pressure gradient(HVPG)can be measured to reflect it in clinical practice.The accuracy of PPG measurements is directly related to patient prognosis.AIM To analyze the correlation between HVPG of three hepatic veins and PPG in patients with PHT.METHODS From January 2017 to December 2019,102 patients with PHT who met the inclusion criteria were evaluated during the transjugular intrahepatic portosystemic shunt procedure and analyzed.RESULTS The mean HVPG of the middle hepatic vein was 17.47±10.25 mmHg,and the mean HVPG of the right and left hepatic veins was 16.34±7.60 and 16.52±8.15 mmHg,respectively.The average PPG was 26.03±9.24 mmHg.The correlation coefficient and coefficient of determination of the right hepatic vein,middle hepatic vein,and left hepatic vein were 0.15 and 0.02(P=0.164);0.25 and 0.05(P=0.013);and 0.14 and 0.02(P=0.013),respectively.The mean wedged hepatic vein/venous pressure(WHVP)of the middle and left hepatic veins was similar at 29.71±12.48 and 29.1±10.91 mmHg,respectively,and the mean WHVP of the right hepatic vein was slightly lower at 28.01±8.95 mmHg.The mean portal vein pressure was 34.11±8.56 mmHg.The correlation coefficient and coefficient of determination of the right hepatic vein,middle hepatic vein,and left hepatic vein were 0.26 and 0.07(P=0.009);0.38 and 0.15(P<0.001);and 0.26 and 0.07(P=0.008),respectively.The average free hepatic venous pressure(FHVP)of the right hepatic vein was lowest at 11.67±5.34 mmHg,and the average FHVP of the middle and left hepatic veins was slightly higher at 12.19±4.88 and 11.67±5.34 mmHg,respectively.The average inferior vena cava pressure was 8.27±4.04 mmHg.The correlation coefficient and coefficient of determination of the right hepatic vein,middle hepatic vein,and left hepatic vein were 0.30 and 0.09(P=0.002);0.18 and 0.03(P=0.078);and 0.16 and 0.03(P=0.111),respectively.CONCLUSION Measurement of the middle hepatic vein HVPG could better represent PPG.Considering the high success rate of clinical measurement of the right hepatic vein,it can be the second choice.

Discontinuous element pressure gradient stabilizations for compressible Navier-Stokes equations based on local projections

A pressure gradient discontinuous finite element formulation for the compressible Navier-Stokes equations is derived based on local projections. The resulting finite element formulation is stable and uniquely solvable without requiring a B-B stability condition. An error estimate is Obtained.

Computed tomography perfusion in liver and spleen for hepatitis B virus-related portal hypertension:A correlation study with hepatic venous pressure gradient

BACKGROUND Hepatic venous pressure gradient(HVPG)is the gold standard for diagnosis of portal hypertension(PH).However,its use can be limited because it is an invasive procedure.Therefore,it is necessary to explore a non-invasive method to assess PH.AIM To investigate the correlation of computed tomography(CT)perfusion of the liver with HVPG and Child-Pugh score in hepatitis B virus(HBV)-related PH.METHODS Twenty-eight patients(4 female,24 male)with gastroesophageal variceal bleeding induced by HBV-related PH were recruited in our study.All patients received CT perfusion of the liver before transjugular intrahepatic portosystemic stent-shunt(TIPS)therapy.Quantitative parameters of CT perfusion of the liver,including liver blood flow(LBF),liver blood volume(LBV),hepatic artery fraction,splenic blood flow and splenic blood volume were measured.HVPG was recorded during TIPS therapy.Correlation of liver perfusion with Child-Pugh score and HVPG were analyzed,and the receiver operating characteristic curve was analyzed.Based on HVPG(>12 mmHg vs≤12 mmHg),patients were divided into moderate and severe groups,and all parameters were compared.RESULTS Based on HVPG,18 patients were classified into the moderate group and 10 patients were classified into the severe group.The Child-Pugh score,HVPG,LBF and LBV were significantly higher in the moderate group compared to the severe group(all P<0.05).LBF and LBV were negatively associated with HVPG(r=-0.473,P<0.05 and r=-0.503,P<0.01,respectively),whereas splenic blood flow was positively associated with hepatic artery fraction(r=0.434,P<0.05).LBV was negatively correlated with Child-Pugh score.Child-Pugh score was not related to HVPG.Using a cutoff value of 17.85 mL/min/100 g for LBV,the sensitivity and specificity of HVPG≥12 mmHg for diagnosis were 80%and 89%,respectively.CONCLUSION LBV and LBF were negatively correlated with HVPG and Child-Pugh scores.CT perfusion imaging is a potential non-invasive quantitative predictor for PH in HBV-related liver cirrhosis.

Characteristics of the pressure profile in the accelerator on the RF negative ion source at ASIPP

Neutral beam injection(NBI)systems based on negative hydrogen ion sources-rather than the positive ion sources that have typically been used to date-will be used in the future magnetically confined nuclear fusion experiments to heat the plasma.The collisions between the fast negative ions and neutral background gas result in a significant number of high-energy positive ions being produced in the acceleration area,and for the high-power long-pulse operation of NBI systems,this acceleration of positive ions back to the ion source creates heat load and material sputtering on the source backplate.This difficulty cannot be ignored,with the neutral gas density in the acceleration region having a significant impact on the flux density of the backstreaming positive ions.In the work reported here,the pressure gradient in the acceleration region was estimated using an ionization gauge and a straightforward 1D computation,and it was found that once gas traveled through the acceleration region,the pressure dropped by nearly one order of magnitude,with the largest pressure drop occurring at the plasma grid.The computation also revealed that the pressure drop in the grid gaps was substantially smaller than that in the grid apertures.

Riemann problem of a Chapman-Jouguet combustion model for pressure-gradient system

In this paper,the Riemann problem of a Chapman-Jouguet combustion model for the pressure-gradient equations is considered.By analyzing in phase space,existence and uniqueness of the solution to the Riemann problem are obtained constructively under the global entropy conditions.

THE EFFECT OF MAGNETIC FIELDS ON LOW FREQUENCY OSCILLATING NATURAL CONVECTION WITH PRESSURE GRADIENT

The oscillating natural convection in the presence of transverse magnetic field with time depending pressure gradient is studied. The analysis of the problem is carried out by assuming that the fluid is flowing in a parallel plate configuration. The emphasis is on low frequency oscillating convective flows induced by g-jitter associated with micro gravity because of their importance to the space processing materials. A general solution for an oscillating flow in the presence of transverse magnetic field is carried out. Some special cases of the oscillating flow and its response to an applied magnetic field are performed. It was observed that the behavior of oscillating free convective flows depends on frequency, amplitude of the driving buoyancy forces, temperature gradient,magnetic field and the electric conditions of the channel walls. In the absence of magnetic field, buoyancy force plays a predominant role in driving the oscillatory flow pattern, and velocity magnitude is also affected by temperature gradients. To suppress the oscillating flow external magnetic field can be used. It is also found that the reduction of the velocity is inversely proportional to the square of the applied magnetic field with conducting wall but directly proportional to the inverse of the magnetic field with insulating wall. Detailed calculations and computational results are also carried out to depict the real situation.

TRANSIENT PRESSURE OF PERCOLATION THROUGH ONE DIMENSION POROUS MEDIA WITH THRESHOLD PRESSURE GRADIENT

This paper studies the transient pressure of percolation during one production and one shutting in one dimension porous media with threshold pressure gradient, the differential equations are derived and solved with numerical computation. Basing on numerical solution, it is analyzed that: 1. the relation between the steady pressure at well bore (or at endpoint) and threshold pressure gradient, shut-in time, and the corresponding formulae are derived; 2, the regulation of transient pressure peak. The result is very useful and will help experiments and applications in the development of low permeability reservoirs with threshold pressure gradient.

Experimental research on characteristic of start-up pressure wave propagation in gelled crude oil by large-scale flow loop

In order to research start-up pressure wave propagation mechanism and determine pressure wave speed in gelled crude oil pipelines accurately,experiment of Large-scale flow loop was carried out.In the experiment,start-up pressure wave speeds under various operation conditions were measured,and effects of correlative factors on pressure wave were analyzed.The experimental and theoretical analysis shows that thermal shrinkage and structural properties of gelled crude oils are key factors influencing on start-up pressure wave propagation.The quantitative analysis for these effects can be done by using volume expansion coefficient and structural property parameter of gelled crude oil.A new calculation model of pressure wave speed was developed on the basis of Large-scale flow loop experiment and theoretical analysis.