Hydrophobic Small-Molecule Polymers as High-Temperature-Resistant Inhibitors in Water-Based Drilling Fluids

Water-based drilling fluids can cause hydration of the wellbore rocks,thereby leading to instability.This study aimed to synthesize a hydrophobic small-molecule polymer(HLMP)as an inhibitor to suppress mud shale hydration.An infrared spectral method and a thermogravimetric technique were used to characterize the chemical composition of the HLMP and evaluate its heat stability.Experiments were conducted to measure the linear swelling,rolling recovery rate,and bentonite inhibition rate and evaluate accordingly the inhibition performance of the HLMP.Moreover,the HLMP was characterized through measurements of the zeta potential,particle size distribution,contact angles,and interlayer space testing.As confirmed by the results,the HLMP could successfully be synthesized with a favorable heat stability.Furthermore,favorable results were found for the inhibitory processes of the HLMP on swelling and dispersed hydration during mud shale hydration.The positively charged HLMP could be electrically neutralized with clay particles,thereby inhibiting diffusion in the double electron clay layers.The hydrophobic group in the HLMP molecular structure resulted in the formation of a hydrophobic membrane on the rock surface,enhancing the hydrophobicity of the rock.In addition,the small molecules of the HLMP could plug the spaces between the layers of bentonite crystals,thereby reducing the entry of water molecules and inhibiting shale hydration.

A Pressure-Drop Model for Oil-Gas Two-Phase Flow in Horizontal Pipes

The accurate prediction of the pressure distribution of highly viscous fluids in wellbores and pipelines is of great significance for heavy oil production and transportation.The flow behavior of high-viscosity fluids is quite different with respect to that of low-viscosity fluids.Currently,the performances of existing pressure-drop models seem to be relatively limited when they are applied to high-viscosity fluids.In this study,a gas-liquid two-phase flow experiment has been carried out using a 60 mm ID horizontal pipe with air and white oil.The experimental results indicate that viscosity exerts a significant influence on the liquid holdup and pressure drop.At the same gas and liquid volume,both the liquid holdup and pressure drop increase with an increase in the viscosity.Combining two existing models,a modified pressure drop method is developed,which is applicable to horizontal pipes for different viscosities and does not depend on the flow pattern.This new method displays a high accuracy in predicting the new experimental data presented here and other published data in literature.

Numerical simulation for erosion effects of three-phase flow containing sulfur particles on elbows in high sour gas fields

Sulfur particles carried by high-speed flow impact pipelines,which may cause equipment malfunctions and even failure.This paper investigates the scouring effect of mist gas containing sulfur particles on elbows in highly sour gas fields.The multiphase-flow hydrodynamic model of the 90
elbow was established by using the computational fluid dynamics(CFD)method.The scouring effects of the gasliquid mist fluid with the water-liquid fraction of 20%and particles with the diameter of 0.01 e0.05mm on elbows were explored within the flow velocity range of 0e20 m/s.In addition,the influences of secondary collision,mean curvature radius to diameter(R/D)ratio,inertial force,drag force,and Stokes number on trajectories of sulfur particles were studied.Moreover,the influences of hydrodynamic parameters of multiphase flow on corrosion inhibitor film were analyzed with the wall shear stress as the reference value.Serious erosion mainly occurred in the extrados of elbow as well as the junction between downstream pipeline and the intrados of elbow,the maximum erosion area occurs at 61.9
.When the incident position of the particle was far away from the top of the inlet plane,the probability of secondary collision became smaller.Furthermore,the erosion rate decreased with the rise in the R/D radio.The maximum erosion rate of elbow increased with the increase in the Stoke number.The maximum erosion rate reached 0.428 mm/a at 0.05mm particle diameter and 20 m/s fluid velocity.The wall shear stress increased with the increase in fluid velocity and mass flow rate of particle,the fitting function of the wall shear stress curve was the Fourier type.The results indicated that highvelocity particles had a serious erosion effect on elbows and affected the stability of the corrosion inhibitor film.The erosion effect could be retarded by controlling the velocity and diameter of particles.The results provided technical supports for the safe production in highly sour gas fields.

Micro-pore structure and oil displacement mechanism analysis for deep zone and low permeability reservoir in Mobei oilfield

The Mobei reservoir is a low-permeability-sandstone reservoir,due to differences in pore geometry,it can be divided into two independent reservoirs:A1 reservoir and A2 reservoir.For better understanding the water flooding development effects of Mobei reservoir,the mercury intrusion porosimetry,water flooding CT scanning and micro-CT scanning experiments are used in this study.The result shows that the reservoir has the strong heterogeneity which is weaken gradually from A1 reservoir to A2 reservoir.Reservoir pore radius is mainly distributed in the 100e200 microns,the throat radius is mainly distributed in the 1e3 micron.The water flooding core experiment in each reservoir shows a short water-free oil production period and rapid water cut after breakthrough.The A2 reservoir core flooding process is similar to piston displacement,the A1 reservoir core flooding process refers to the phenomenon(The fingering phenomenon in the process of core flooding in the A1 reservoir is obvious).The calculated water drive efficiency of the A2 reservoir is 61.2%,which is higher than 49.1%of the A1 reservoir.According to the CT scanning process,the Mobei oilfield has low micro displacement efficiency and the A1 reservoir has a smaller spread(sweep area)and higher residual oil saturation.

A novel double polymer modified hydrophobic/hydrophilic stationary phase for liquid chromatography

In this paper,norbornene imidazolium hexafluorophosphate(NM-MIm-PF6)was modified on the surface of aminopropyl silica by ring-opening metathesis polymerization(ROMP),and then oligo(ethylene glycol)methacrylate(OEGMA)were grafted on the surface by atom transfer radical polymerization(ATRP).Some characterizations in this article confirmed that the synthesis of P(NM-MIm-PF6)-SiPOEGMA(Pl-Si-P2)is successful.The P1-Si-P2 can separate sugars,amino acids,sulfonamides in a hydrophilic interaction mode and alkyl benzene,polycyclic aromatic hydrocarbon in a reverse phase mode.The experiment also found that the column has typical characte ristics of hydrophobic/hydrophilic separation mechanism.Compared to single hydrophobic C18 column and single hydrophilic Si-NH2 column,this P1-Si-P2 shows certain advantages.