Effect of hydrophilic silica nanoparticles on hydrate formation: Insight from the experimental study

Invasion of drilling fluid into natural gas hydrate deposits during drilling might damage the reservoir,induce hydrate dissociation and then cause wellbore instability and distortion of the data from well logging. Adding nanoparticles into drilling fluid is an effective method in reducing the invasion of drilling fluid and enhancing borehole stability. However, the addition of nanoparticles might also introduce hydrate formation risk in borehole because they can act as the "seeds" for hydrate nucleation. This paper presents an experimental study of the effect of hydrophilic silica nanoparticle on gas hydrate formation in a dynamic methane/liquid-water system. In the experiment, the ultrapure water with and without1.0 wt%–6.0 wt% concentrations of silica nanoparticles, grain sizes of 20 and 50 nm, were pressurized by methane gas under varied conditions of temperature and pressure. The induction time, the gas consumption, and the average rate of gas consumption in the system were measured and compared to those in ultrapure water. The results show that a concentration of 4.0 wt% hydrophilic SiO_2 particles with a grain size of 50 nm has a relatively strong inhibition effect on hydrate formation when the initial experimental condition is 5.0 °C and 5.0 MPa. Compared to ultrapure water, the hydrophilic nano-SiO_2 fluid increases the induction time for hydrate formation by 194% and decreases the amount and average rate of hydrate formation by 10% and 17%, respectively. This inhibition effect may be attributed to the hydrophilicity,amount and aggregation of silica nanoparticle according to the results of water activity and zeta potential measurements. Our work also elucidates hydrophilic, instead of hydrophobic, nanoparticles can be added to the drilling fluid to maintain wellbore stability and to protect the hydrate reservoir from drilling mud damage, because they exhibit certain degree of hydrate inhibition which can reduce the risk of hydrate reformation and aggregation during gas hydrate or deep water drilling if their concentration can be controlled properly.

Gas-hydrate formation,agglomeration and inhibition in oil-based drilling fluids for deep-water drilling

One of the main challenges in deep-water drilling is gas-hydrate plugs,which make the drilling unsafe.Some oil-based drilling fluids（OBDF） that would be used for deep-water drilling in the South China Sea were tested to investigate the characteristics of gas-hydrate formation,agglomeration and inhibition by an experimental system under the temperature of 4 ？C and pressure of 20 MPa,which would be similar to the case of 2000 m water depth.The results validate the hydrate shell formation model and show that the water cut can greatly influence hydrate formation and agglomeration behaviors in the OBDF.The oleophobic effect enhanced by hydrate shell formation which weakens or destroys the interfacial films effect and the hydrophilic effect are the dominant agglomeration mechanism of hydrate particles.The formation of gas hydrates in OBDF is easier and quicker than in water-based drilling fluids in deep-water conditions of low temperature and high pressure because the former is a W/O dispersive emulsion which means much more gas-water interfaces and nucleation sites than the later.Higher ethylene glycol concentrations can inhibit the formation of gas hydrates and to some extent also act as an anti-agglomerant to inhibit hydrates agglomeration in the OBDF.

Comparison and application of different empirical correlations for estimating the hydrate safety margin of oil-based drilling fluids containing ethylene glycol

As the oil and gas industries continue to increase their activity in deep water, gas hydrate hazards will become more serious and challenging, both at present and in the future. Accurate predictions of the hydrate-free zone and the suitable addition of salts and/or alcohols in preparing drilling fluids are particularly important both in preventing hydrate problems and decreasing the cost of drilling operations. In this paper, we compared several empirical correlations commonly used to estimate the hydrate inhibition effect of aqueous organic and electrolyte solutions using experiments with ethylene glycol （EG） as a hydrate inhibitor. The results show that the Najibi et al. correlation （for single and mixed thermodynamic inhibitors） and the Ostergaard et al. empirical correlation （for single thermodynamic inhibitors） are suitable for estimating the hydrate safety margin of oil-based drilling fluids （OBDFs） in the presence of thermodynamic hydrate inhibitors. According to the two correlations, the OBDF, composed of 1.6 L vaporizing oil, 2% emulsifying agent, 1% organobentonite, 0.5% SP-1, 1% LP-1, 10% water and 40% EG, can be safely used at a water depth of up to 1900 m. However, for more accurate predictions for drilling fluids, the effects of the solid phase, especially bentonite, on hydrate inhibition need to be considered and included in the application of these two empirical correlations.

ICAM-1 depletion in the center of immunological synapses is important for calcium releasing in T-cells

T-cell activation requires the formation of the immunological sy napse(IS)bet ween a T-cll and anantigen-presenting cell(AP C)to control the development of the adaptive immune response.How-ever,calcium release,an initial signal of T-cell activation,has been found to occur before IS for-mation.The mechanism for triggering the calcium signaling and relationship bet ween calciumrelease and IS format ion remains unclear.Herein,using live-cell imaging,we found that int ercellularadhesion molecule 1(ICAM-1),an essential mdlecule for IS formation,accumulated and then wasdepleted at the center of the synapse before complete IS formation.During the proces of ICAM1depletion,calcium was released.if ICAM-1 failed to be depleted from the center of the synapse,thesustained calcium signaling could not be induced.Moreover,depletion of ICAM-1 in ISs preferen-tially ccurred with the contact of antigen-specific T-cels and dendritic clls(DCs).Blocking thebinding ofICA M-1 and lymphocy te finction-associated antigen 1(LFA-1),ICAM-1 failed to depleteat the center of the synapse,and calcium release in T-clls decreased.In studying the mechanism ofhow the depletion ofiCA M1 could influence calcium release in T-clls,we found that the movementof ICAM-1 was associat ed with the localization of LFA-1 in the IS,which afected the localization ofcalcium microdomains,ORAIl and mitochondria in IS.Therefore,the depletion of ICAM-1 in the center of the synapse is an important factor for an initial sust ained calcium release in T-cells.

Research on formation density MWD instrument in engineering geological exploration

A high efficiency method is very important in geological survey for a new city in China.Geophysical parameters are Measured While Drilling(MWD),and these parameters are processed and explained on the ground,so the method can replace conventional engineering geological exploration for drilling rock sample.According petroleum engineering MWD,using the different characters of different rock absorbs γ radial,with the method of storing data in hole and explaining data on the ground,engineering geological exploration formation density MWD is researched.The MWD works stabilized,and the performance is good with precise data.

CD44 and Hematologic Malignancies

The expression of CD44 was upregulated in some hematological malignancies and is associated with metastasis and prognosis. The ligation of CD44 with specific monoclonal antibodies can trigger terminal differentiation of leukemic blasts in some subtypes, so it is probable to develop an anti-CD44 based differentiation therapy in leukemia. The effects of CD44 and its monoclonal antibodies are discussed in this review. Cellular ＆ Molecular Immunology.

Relationship between Cytokines and Leukocytosis in Patients with APL Induced by All-Trans Retinoic Acid or Arsenic Trioxide

Leukocytosis or hyperleukocytosis occurs during ATRA or arsenic trioxide differentiation therapy, which is related to the RA syndrome. The number of WBC often increased by ten or more times as high as that of pretreatment, around 7 to 20 days after treatment with ATRA or arsenic trioxide. Usually, when number of WBC tended to peak, there was concomitance with down-regulation of promyelocytes, up-regulation of myelocytes and more mature neutrophils. The same trend of classification of BM was observed in most of the patients with APL to whom leukocytosis happened. Although the mechanism of leukocytosis has not been demonstrated clearly, so far the proliferation hypothesis by cytokines and rheological hypothesis by adhesion molecules were taken into consideration. Otherwise, hypothesis about more divisions of differentiated myelocytes induced by ATRA or arsenic trioxide remains unclear. Usually, this kind of leukocytosis or hyperleukocytosis itself requires no additional cytotoxic treatment.

Effect on the Performance of Drilling Fluids at Downhole Rock Surfaces at Low Temperatures

To maintain gas hydrate stability, low-temperature drilling fluids and high drilling speeds should be used while drilling in gas hydrate-bearing sediments. The effect of the drilling fluid on downhole rock surfaces at low temperatures is very important to increase the drilling rate. This paper analyzed the action mechanism of the drilling fluid on downhole rock surfaces and established a corresponding evaluation method. The softening effect of six simulated drilling fluids with 0.1 wt.% of four common surfactants and two common organic salts on the downhole rock surface strength was evaluated experimentally using the established method at low temperature. The experimental results showed that the surfactants and organic salts used in the drilling fluids aided in the reduction of the strength of the downhole rock surface, and the established evaluation method was able to quantitatively reveal the difference in the softening effect of the different drilling fluids through comparison with water. In particular, the most common surfactant that is used in drilling fluids, sodium dodecyl sulfate（SDS）, had a very good softening effect while drilling under low-temperature conditions, which can be widely applied during drilling in low-temperature formations, such as natural gas hydrate-bearing sediments, the deep seafloor and permafrost.