Simulation of pipelining pours point depressant beneficiated waxy crude oil through China West Crude Oil Pipeline

Flow properties of waxy crude oils,particularly the beneficiated waxy crude oils,are sensitive to shear history that the crude oil experienced,called the shear history effect.To simulate this shear history effect accurately is vital to pipeline design and operation.It has been demonstrated by our previous that the energy dissipation or entropy generation due to viscous flow in the shear process is a suitable parameter for simulating the shear history effect.In order to further verify the reliability of this approach,experimental simulations were conducted for three PPD-beneficiated waxy crude oils transported through the China West Crude Oil Pipeline,a most complicated long-distance-crude-oil-pipeline technically and operationally so far in China.The simulations were made by using a stirred vessel and with the energy dissipation of viscous flow as the shear simulation parameter.Comparison between the flow properties of crude oils obtained from field test and experimental simulations,it is found that the gel points and viscosities from experimental simulations are in good agreement with the field data.

Rheological study of methane gas hydrates in the presence of micron-sized sand particles

Natural gas hydrates,intricate crystalline structures formed by water molecules and small gas molecules,have emerged as a significant and globally impactful clean energy resource.However,their commercial exploitation faces challenges,particularly operational disruptions caused by sand-related blockages.Understanding the rheological properties of hydrate slurry,especially in the presence of micron-sized sand particles,is imperative for ensuring the flow assurance of subsea hydrate exploitation.This study extensively investigates the rheological properties of sand-containing hydrate slurries.The findings reveal that these slurries exhibit non-Newtonian fluid characteristics,including yield stress,thixotropy,and shear-thinning behavior.Solid-like elastic features are observed in sand-containing hydrate slurries before yielding,transitioning to viscous behavior after yielding.Even with a minimal amount of sand,both static yield stress and yield strain experience substantial changes,correlating with the increase in sand concentration.The research conclusively establishes the thixotropic nature of sand-hydrate slurries,where the viscosity decay rate is directly influenced by the shear rate.These insights aim to contribute comprehensively to the development of effective flow assurance strategies,ensuring the safe and stable operation of subsea hydrate exploitation.

An Auxiliary Monitoring Method for Well Killing Based on Statistical Data

In the present study,a large set of data related to well killing is considered.Through a complete exploration of the whole process leading to well-killing,various factors affecting such a process are screened and sorted,and a correlation model is built accordingly in order to introduce an auxiliary method for well-killing monitoring based on statistical information.The available data show obvious differences due to the diverse control parameters related to different well-killing methods.Nevertheless,it is shown that a precise three-fold relationship exists between the reservoir parameters,the elapsed time and the effectiveness of the considered well-killing strategy.The proposed monitoring auxiliary method is intended to support risk assessment and optimization in the context of typical well-killing applications.

Investigations on methane hydrate formation,dissociation,and viscosity in gas-water-sand system

Understanding the kinetics and viscosity of hydrate slurry in gas-water-sand system is of great significance for the high-efficiency and high-safety development of natural gas hydrates.The effect of micronsized sands with various concentrations and particle sizes on the hydrate formation,dissociation,and viscosity in gas-water-sand system are investigated in this work.The experimental results show that the hydrate induction time in the sandy system is slightly prolonged compared to the pure gas-water system,and the inhibition effect first strengthens and then weakens as the sand concentration increases from0 wt%to 5 wt%.Besides,the difference of hydrate formation amount in various cases is not obvious.The concentration and particle size of sand have little effect on the kinetics of hydrate formation.Both promoting and inhibiting effects on hydrate formation have been found in the sandy multiphase fluid.For the viscosity characteristics,there are three variations of hydrate slurry viscosity during the formation process:Steep drop type,S-type and Fluctuation type.Moreover,appropriate sand size is helpful to reduce the randomness of slurry viscosity change.Meanwhile,even at the same hydrate volume fraction,the slurry viscosity in the formation process is significantly higher than that in dissociation process,which needs further research.This work provides further insights of hydrate formation,dissociation,and viscosity in gas-water-sand system,which is of great significance for safe and economic development of natural gas hydrates.

Dynamic simulation of GEH-IES with distributed parameter characteristics for hydrogen-blending transportation

For the purpose of environment protecting and energy saving,renewable energy has been distributed into the power grid in a considerable scale.However,the consuming capacity of the power grid for renewable energy is relatively limited.As an effective way to absorb the excessive renewable energy,the power to gas(P2G)technology is able to convert excessive renewable energy into hydrogen.Hydrogen-blending natural gas pipeline is an efficient approach for hydrogen transportation.However,hydrogen-blending natural gas complicates the whole integrated energy system(IES),making it more problematic to cope with the equipment failure,demand response and dynamic optimization.Nevertheless,dynamic simulation of distribution parameters of gas-electricity-hydrogen(GEH)energy system,especially for hydrogen concentration,still remains a challenge.The dynamics of hydrogen-blending IES is undiscovered.To tackle the issue,an iterative solving framework of the GEH-IES and a cell segment-based method for hydrogen mixing ratio distribution are proposed in this paper.Two typical numerical cases studying the conditions under which renewables fluctuate and generators fail are conducted on a real-word system.The results show that hydrogen blending timely and spatially influences the flow parameters,of which the hydrogen mixing ratio and gas pressure loss along the gas pipeline are negatively correlated and the response to hydrogen mixing ratio is time-delayed.Moreover,the hydrogen-blending amount and position also have a significant impact on the performance of the compressor.