Numerical simulation of pressure pulse decay experiment on crushed low permeability rocks considering Klinkenberg effect and gas absorption/desorption

Pressure pulse decay method is widely used for permeability tests for low permeability rock plug samples. This method can be used for crushed grain samples by removing the downstream chamber in standard pulse decay tests. Processes in pulse decay tests for low permeability crushed shale are investigated using numerical simulation. Both the Klinkenberg slip effect for gas flows in low permeability rock and the gas absorption/desorption in the porous matrix are considered. The complete mathematical model is set up to include the two effects. Deviation of the numerical pulse decay curve from the analytical one with an assumption that the pressure keeps a constant in the porous sample is investigated. The relative importance of gas absorption/desorption and gas compressibility is also investigated quantitatively. According to the present investigation, gas compressibility and adsorption both make negative contributions to the permeating process. A potential two-curve method is proposed to decide absolute permeability and the Klinkenberg coefficient when these two parameters cannot be distinguished using one pulse decay curve during the inverse fitting procedure. These two parameters can be determined at the same time only if the experiment is conducted under big initial pressure difference and the Klinkenberg coefficient has at least the same order of magnitude as the pressure

Composite rock-breaking of high-pressure CO2 jet & polycrystallinediamond-compact (PDC) cutter using a coupled SPH/FEM Model

Acknowledgments This work was supported by the National Natural Science Foundation of China (Grant No. 52004236), Sichuan Science and Technology Program (Grant No. 2021JDRC0114), the Starting Project of SWPU (Grant No.2019QHZ009), the China Postdoctoral Science Foundation (Grant No.2020M673285), the Open Project Program of Key Laboratory of Groundwater Resources and Environment (Jilin University), Ministry of Education (Grant No.202005009KF), and the Chinese Scholarship Council (CSC) funding (CSC NO.202008515107) for the financial support of this work.Peer reviewedPublisher PD

The influence on coagulant of patients with cancer by PICC placement

目的  研究PICC置管对肿瘤患者凝血功能的影响。方法  应用ELISA方法测定46例肿瘤患者在PICC前1天、置管后1天、置管后30天和置管后90天四次共147例次血浆D-二聚体（ D-D）、凝血酶原时间（PT）、部分凝血活酶时间（APTT）、凝血酶时间（TT）、抗凝血酶Ⅲ（ATⅢ）、纤维蛋白原（Fib）和血小板（PLT）计数，分析PICC对凝血功能的影响。结果  （1）置管前后四次的血浆D-D水平均明显高于正常参考值，但四次之间无明显差异（P>0.05） 。（2）血浆PT、APTT、TT、ATⅢ、Fib水平和PLT计数均在正常参考值范围，且四次比较均无统计学意义（均为 P＞0.05）。（3）化疗未置管的48例中无一例有血栓形成，置管88例中有3例发生血栓，两者比较无统计学意义（P=0.27）。结论  肿瘤患者PICC置管前后血浆D-D、PT、APTT、TT、ATⅢ、Fib水平和PLT计数等各项指标均无明显变化；血浆D-D水平虽均升高，但与PICC也无关。PICC对凝血功能影响不大，是安全可行的辅助治疗手段。Objective: To study the influence on coagulant of patients with cancer by PICC placement. Methods: To test the plasma levels of D-dimer(D-D),prothrombin(PT),activated partial thromplasmtin(APTT),thrombin time(TT),antithrombin(ATⅢ),fibrinogen(Fib) and platelet count by ELISA in 46 patients with cancer in one day before PICC placement, in one day,30 day, and 90 day after PICC placement, and analyses the change feature and clinical significance. Results: (1)The levels of plasma D-D were higher than control group in both pre-PICC placement and post-PICC placement, but there were no differences in both pre-PICC placement and post-PICC placement(P>0.05).(2)The levels of plasma PT, APTT,TT,ATⅢ,Fib and platelet were not different in both pre-PICC placement and post-PICC placement(all P>0.05),and there were no differences from control group.(3)There were no cases with thromboembolism in 48 cancer patients without PICC placement, and  3 cases of thromboembolism occurred among 88 cancer patients treated with PICC placement. But there were no significances(P=0.27). Conclusion: Therelevels of D-D,PT,APTT,TT,ATⅢ, Fib and platelet in patients with cancer did not change in both pre-PICC placement and post-PICC placement. There was no effect of coagulant on patients with cancer by PICC placement. The PICC placement was safe