A two-phase type-curve method with multiscale fluid transport mechanisms in hydraulically fractured shale reservoirs

The quantitative understanding of hydraulic fracture(HF)properties guides accurate production forecasts and reserve estimation.Type curve is a powerful technique to characterize HF and reservoir properties from flowback and long-term production data.However,two-phase flow of water and hydrocarbon after an HF stimulation together with the complex transport mechanisms in shale nanopores exacerbate the nonlinearity of the transport equation,causing errors in type-curve analysis.Accordingly,we propose a new two-phase type-curve method to estimate HF properties,such as HF volume and permeability of fracture,through the analysis of flowback data of multi-fractured shale wells.The proposed type curve is based on a semianalytical solution that couples the two-phase flow from the matrix with the flow in HF by incorporating matrix influx,slippage effect,stress dependence,and the spatial variation of fluid properties in inorganic and organic pores.For the first time,multiple fluid transport mechanisms are considered into two-phase type-curve analysis for shale reservoirs.We analyze the flowback data from a multi-fractured horizontal well in a shale gas reservoir to verify the field application of the proposed method.The results show that the fracture properties calculated by the type-curve method are in good agreement with the long-time production data.

Effect of viral hepatitis on type 2 diabetes:A Mendelian randomization study

BACKGROUND The effects of viral hepatitis(VH)on type 2 diabetes(T2D)remain controversial.AIM To analyze the causal correlation between different types of VH and T2D using Mendelian randomization(MR).METHODS Single nucleotide polymorphisms of VH,chronic hepatitis B(CHB),chronic hepatitis C(CHC)and T2D were obtained from the BioBank Japan Project,European Bioinformatics Institute,and FinnGen.Inverse variance weighted,MREgger,and weighted median were used to test exposure-outcome associations.The MR-Egger intercept analysis and Cochran’s Q test were used to assess horizontal pleiotropy and heterogeneity,respectively.Leave-one-out sensitivity analysis was used to evaluate the robustness of the MR analysis results.RESULTS The MR analysis showed no significant causal relationship between VH and T2D in Europeans[odds ratio(OR)=1.028;95%confidence interval(CI):0.995-1.062,P=0.101].There was a negative causal association between CHB and T2D among East Asians(OR=0.949;95%CI:0.931-0.968,P<0.001),while there was no significant causal association between CHC and T2D among East Asians(OR=1.018;95%CI:0.959-1.081,P=0.551).Intercept analysis and Cochran’s Q test showed no horizontal pleiotropy or heterogeneity(P>0.05).Sensitivity analysis showed that the results were robust.CONCLUSION Among East Asians,CHB is associated with a reduced T2D risk,but this association is limited by HBV load and cirrhosis.Although VH among Europeans and CHC among East Asians are not associated with the risk of T2D,focusing on blood glucose in patients with CHC is still relevant for the early detection of T2D induced by CHCmediated pathways of hepatic steatosis,liver fibrosis,and cirrhosis.

Correlation between cerebral neurotransmitters levels by proton magnetic resonance spectroscopy and HbA1c in patients with type 2 diabetes

BACKGROUND Cognitive dysfunction is the main manifestation of central neuropathy.Although cognitive impairments tend to be overlooked in patients with diabetes mellitus(DM),there is a growing body of evidence linking DM to cognitive dysfunction.Hyperglycemia is closely related to neurological abnormalities,while often disregarded in clinical practice.Changes in cerebral neurotransmitter levels are associated with a variety of neurological abnormalities and may be closely related to blood glucose control in patients with type 2 DM(T2DM).AIM To evaluate the concentrations of cerebral neurotransmitters in T2DM patients exhibiting different hemoglobin A1c(HbA1c)levels.METHODS A total of 130 T2DM patients were enrolled at the Department of Endocrinology of Shanghai East Hospital.The participants were divided into four groups according to their HbA1c levels using the interquartile method,namely Q1(<7.875%),Q2(7.875%-9.050%),Q3(9.050%-11.200%)and Q4(≥11.200%).Clinical data were collected and measured,including age,height,weight,neck/waist/hip circumferences,blood pressure,comorbidities,duration of DM,and biochemical indicators.Meanwhile,neurotransmitters in the left hippocampus and left brainstem area were detected by proton magnetic resonance spectroscopy.RESULTS The HbA1c level was significantly associated with urinary microalbumin(mALB),triglyceride,low-density lipoprotein cholesterol(LDL-C),homeostasis model assessment of insulin resistance(HOMA-IR),and beta cell function(HOMA-β),N-acetylaspartate/creatine(NAA/Cr),and NAA/choline(NAA/Cho).Spearman correlation analysis showed that mALB,LDL-C,HOMA-IR and NAA/Cr in the left brainstem area were positively correlated with the level of HbA1c(P<0.05),whereas HOMA-βwas negatively correlated with the HbA1c level(P<0.05).Ordered multiple logistic regression analysis showed that NAA/Cho[Odds ratio(OR):1.608,95%confidence interval(95%CI):1.004-2.578,P<0.05],LDL-C(OR:1.627,95%CI:1.119-2.370,P<0.05),and HOMA-IR(OR:1.107,95%CI:1.031-1.188,P<0.01)were independent predictors of poor glycemic control.CONCLUSION The cerebral neurotransmitter concentrations in the left brainstem area in patients with T2DM are closely related to glycemic control,which may be the basis for the changes in cognitive function in diabetic patients.

Frequency of the C677T Polymorphism of MTHFR, G20210A of Prothrombin and R506Q of Factor V Leiden in Type 2 Diabetics in Abidjan

In Africa, the prevalence of diabetes is escalating and remains a concern due to the numerous complications it causes. Vascular damage associated with diabetes leads to a prothrombotic state observed in diabetic individuals. Diabetes is a complex and multifactorial disease involving genetic components. With the aim of preventing complications and contributing to an efficient management of diabetes, we investigated genes likely to lead to a risk of thrombosis, in particular the C677T of MTHFR, G20210A of prothrombin, and R506Q of factor V Leiden in type 2 diabetics in Abidjan receiving ambulatory care. A descriptive cross-sectional study was carried out on consenting type 2 diabetic patients. Mutation detection was carried out using the PCR-RFLP method employing restriction enzymes. Hemostasis tests (fibrinogen, D-dimers, fibrin monomers, and von Willebrand factor) were performed using citrate tubes on the Stage? Star Max automated system. Plasminogen activator inhibitor was assayed by ELISA method, and biochemical parameters were determined using the COBAS C311. The study population consisted of 45 diabetic patients, 51.1% of whom presented vascular complications, mainly neuropathy. Disturbances in hemostasis parameters were observed, with 15.5% of patients showing an increase in fibrin monomers. Mutation analysis revealed an absence of factor V mutation (factor V Leiden) and of G20210A mutation of the prothrombin gene. However, 15.6% of subjects had a heterozygous C677T mutation of MTHFR, with 57% of them being anemic. The exploration of biological and genetic factors associated with thrombotic risk is of significant interest in the optimal management of African type 2 diabetics.

Blasingame production decline type curves for analysing a multi-fractured horizontal well in tight gas reservoirs

Production decline analysis has been considered as an important method to obtain the flow parameters, reservoir properties and original gas in place. Although advanced Blasingame production decline analysis methods for vertical wells, fractured wells and horizontal wells are widely used, limited study has conducted on Blasingame production decline type curves for multi-fractured horizontal well(MFHW). Based on the perpendicular bisection(PEBI) grids, a numerical model was developed and the solution was obtained using control volume finite element method and the fully implicit method. Blasingame production decline-type curves of the infinitely conductive MFHW were plotted through computer programming. A field case was presented to analyse and verify the model developed. Five flow regimes, including early formation linear flow, early radial flow, compound linear flow, transient flow and pseudo-radial flow, are recognized. Fracture spacing is the main factor that affects early radial flow, compound linear flow and transient flow, the distance from the well to the circular boundary affects the pseudo-radial flow, and the type curves are also significantly affected by the formation permeability, fracture number and fracture half-length. The validation of field case suggests that the Blasingame production decline type curves proposed in this work can be applied to the production decline analysis for MFHW in tight gas reservoirs.

Large deflection of curved elastic beams made of Ludwick type material

The large deflection of an axially extensible curved beam with a rectangular cross-section is investigated. The elastic beam is assumed to satisfy the Euler-Bernoulli postulation and be made of the Ludwick type material. Through reasonably simplified integration, the strain and curvature of the axis of the beam are presented in implicit formulations. The governing equations involving both geometric and material nonlin- earities of the curved beam are derived and solved by the shooting method. When the initial curvature of the beam is zero, the curved beam is degenerated into a straight beam, and the predicted results obtained by the present model are consistent with those in the open literature. Numerical examples are further given for curved cantilever and simply supported beams, and the couplings between elongation and bending are found for the curved beams.

A novel type curve for estimating oil recovery factor of gas flooding

A novel type curve is presented for oil recovery factor prediction suitable for gas flooding by innovatively introducing the equivalent water-gas cut to replace the water cut,comprehensively considering the impact of three-phase flow(oil,gas,water),and deriving the theoretical equations of gas flooding type curve based on Tong’s type curve.The equivalent water-gas cut is the ratio of the cumulative underground volume of gas and water production to the total underground volume of produced fluids.Field production data and the numerical simulation results are used to demonstrate the feasibility of the new type curve and verify the accuracy of the prediction results with field cases.The new type curve is suitable for oil recovery factor prediction of both water flooding and gas flooding.When a reservoir has no gas injected or produced,the gas phase can be ignored and only the oil and water phases need to be considered,in this case,this gas flooding type curve returns to the Tong’s type curve,which can evaluate the oil recovery factor of water flooding.For reservoirs with equivalent water-gas cuts of 60%-80%,the regression method of the new type curve works well in predicting the oil recovery factor.For reservoirs with equivalent water-gas cuts higher than 80%,both the regression and assignment methods of the new type curve can accurately predict the oil recovery factor of gas flooding.

Solution and Type Curve Analysis of Fluid Flow Model for Fractal Reservoir

Conventional pressure-transient models have been developed under the assumption of homogeneous reservoir. However, core, log and outcrop data indicate this assumption is not realistic in most cases. But in many cases, the homogeneous models are still applied to obtain an effective permeability corresponding to fictitious homogeneous reservoirs. This approach seems reasonable if the permeability variation is sufficiently small. In this paper, fractal dimension and fractal index are introduced into the seepage flow mechanism to establish the fluid flow models in fractal reservoir under three outer-boundary conditions. Exact dimensionless solutions are obtained by using the Laplace transformation assuming the well is producing at a constant rate. Combining the Stehfest’s inversion with the Vongvuthipornchai’s method, the new type curves are obtained. The sensitivities of the curve shape to fractal dimension (θ) and fractal index (d) are analyzed;the curves don’t change too much when θ is a constant and d change. For a closed reservoir, the up-curving has little to do with θ when d is a constant;but when θ is a constant, the slope of the up-curving section almost remains the same, only the pressure at the starting point decreases with the increase of d;and when d = 2 and θ = 0, the solutions and curves become those of the conventional reservoirs, the application of this solution has also been introduced at the end of this paper.

C^n-CONTINUOUS B-TYPE SPLINE CURVES WITH ITSLOCALIZATION INTERPOLATION AND APPROXIMATION

This paper presents a class of Cn- continuous B- type spline curves with some paramet- ric factors.The length of their local support is equal to4.Taking the different values of the parametric factors,the curves can become free- type curves or interpolate a set of given points even mix the both cases.When the parametric factors satisfy the certain conditions,the degrees of the curves can be decreased as low as possible.Besides,when all the parametric factors tend to zero,the curves globally approximate to the control polygon.

Attenuation-type and failure-type curve models on accumulated pore water pressure in saturated normal consolidated clay

Based on dynamic triaxial test results of saturated soft clay,similarities of variations between accumulated pore water pressure and accumulated deformation were analyzed.The Parr's equation on accumulated deformation was modified to create an attenuation-type curve model on accumulated pore water pressure in saturated normal consolidation clay.In this model,dynamic strength was introduced and a new parameter called equivalent dynamic stress level was added.Besides,based on comparative analysis on variations between failure-type and attenuation-type curves,a failure-type curve model was created on accumulated pore water pressure in saturated normal consolidation clay.Two models can take cycle number,coupling of static and dynamic deviator stress,and consolidation way into consideration.The models are verified by test results.The correlation coefficients are more than 0.98 for optimization of test results based on the two models,and there is good agreement between the optimized and test curves,which shows that the two models are suitable to predict variations of accumulated pore water pressure under different loading cases and consolidation ways.In order to improve prediction accuracy,it is suggested that loading cases and consolidation ways should be consistent with in-situ conditions when dynamic triaxial tests are used to determine the constants in the models.

Type Curves Relating Well Spacing and Heterogeneity to Oil Recovery in a Water Flooded Reservoir—A Case Study

The design of an optimum spacing between oil wells entails both reservoir characterization and economics considerations. High hydrocarbon recovery requires short distances between wells. However, higher well density leads to a greater development cost. Accordingly, determination of an optimum well spacing is primordial in the development of oil fields. As a matter of fact, the identification of optimum well spacing for heterogeneous sandstone reservoirs undergoing waterflooding requires extensive analytical and numerical studies. The intent of this work is therefore to develop type curves as a quick tool in estimating ultimate recovery and reduce excessive reservoir simulation cost in analog reservoirs. These type curves utilize reservoir heterogeneity and well spacing in the estimating of oil recovery. In this work, we investigated numerically the effects of heterogeneity and well spacing on ultimate recovery using Eclipse black oil simulation and PEEP economic software 2015 and 2009 versions, respectively. The study involved a 50-ft thick Middle Eastern reservoir with porosity variability ranging from 0.2 to 0.9. Corresponding average matrix permeabilities of 1, 10 and 100 md were considered. Type curves relating well spacing and heterogeneity to ultimate oil recovery were developed. Type curves and net present value calculations indicated that there is exists an ultimate well spacing for each of the considered matrix permeabilities.

Type 2 dynamic curves: A diagnostic dilemma

BACKGROUND Magnetic resonance imaging(MRI)with multiparametric dynamic contrast plays a critical role in the assessment of breast lesions.Dynamic curves are a critical parameter in determining the benign or malignant nature of lesions.Dynamic curves of type 1 are known to represent benign masses,while dynamic curves of type 3 are known to identify malignant masses.Type 2 dynamic curves have a sensitivity of 42.6%and specificity of 75%for malignancy detection.AIM To investigate the pathological diagnosis of lesions with type 2 dynamic curves.METHODS We evaluated breast MRI examinations performed between 2020 and 2021 retrospectively and included lesions with type 2 dynamic curves.We included 38 lesions from 33 patients.The lesions were evaluated for their pathological diagnosis and morphological characteristics.RESULTS Twenty-six lesions were malignant,while twelve were benign.The most frequently encountered benign lesion(7/12,58.3%)was sclerosing adenosis,while the most frequently encountered malignant diagnosis was invasive ductal cancer.The presence of a type 2 dynamic curve had a sensitivity of 40.2%and specificity of 73.4%for predicting malignancy.By combining type 2 curves and morphological features,the sensitivity and specificity were increased.CONCLUSION The high rates of malignancy detected histopathologically among patients with type 2 dynamic curves in our study are remarkable.Type 2 dynamic curves can be detected in benign breast masses,especially in sclerosing adenosis cases.Considering morphological features can increase the diagnostic accuracy in cases with type 2 dynamic curves.

WEAK TYPE ESTIMATES FOR THE MAXIMAL OPERATORS ASSOCIATED TO PLANE CURVES

For the plane curves Γ,the maximal operator associated to it is defined by Mf(x)=sup|∫f(x-Γ(t))(r^(-1)t)r^(-1)dt| where is a Schwartz function.For a certain class of curves in R^2,M is shown to bounded on (H(R^2),Weak L^1(R^2).This extends the theorem of Stein & Wainger and the theo- rem of Weinberg.

A PICARD-TYPE THEOREM AND A UNIQUENESS THEOREM OF NON-ARCHIMEDEAN ANALYTIC CURVES IN PROJECTIVE SPACE

In this article, we prove a Picard-type Theorem and a uniqueness theorem for non-Archimedean analytic curves in the projective space Pn(F), where the characteristic of F is 0 or positive. In the main results of this article, we ignore the zeros with large multiplicities.

Pressure Buildup Analysis Using Type Curves for a Well in a Pressure-Maintained System

The development and application of a new solution is demonstrated for the type-curve analysis and in-terpretation of well test data from a multiwell reservoir system of both production and injection wells with two-phase flow. The buildup type curves or buildup behavior could be obtained through the solution by using su-perposition. But a new outer boundary condition for variable pressure boundary must be introduced to obtain the correct pressure buildup solutions by superposition. A technique is shown to determine the deviation time from the infinite-acting semilog radial flow stabilization in the derivatives of pressure, which is calculated with respect to and plotted vs. shut-in time. Field examples are given to illustrate the use of the proposed method for analyzing transient pressure data from a well located in a multi-well water-injection reservoir. An adaptive genetic algorithm-based method is used to match the pressure and pressure derivative data to estimate reservoir parameters. The validity and applicability of the proposed method are also demonstrated through the examples.

A Review of Geothermal Type-Curves with Damage Effect: A Case of Practical Apply to a Mexican Geothermal Field

A review of the art state was developed about the inflow relationships and their application for reservoir characterization. The theoretical development of the methodology for determining the damage effect using type-curves of the inflow relationships was shown. We show the process followed for achieve the geothermal type-curve affected with damage for reservoirs with mean salinities of 30000 ppm and temperatures up to 350℃. This type-curve was applied using measurement production data in a Mexican geothermal field. According with the obtained results is shown that the methodology for determining the damage effect using production measurements is a sure alternative for the damage effect calculation. It was used an alternative methodology in order to validate the damage presence and the obtained results were consistent. Last thing shows that both methodologies can be combined as a confident manner.

基于可靠性的液化气体运输船新颖C型货物围护系统设计衡准

从结构可靠性分析方法入手,分析液化气体运输船新颖C型货物围护系统的载荷、抗力和模型的随机性。建立新颖C型货物围护系统的极限状态方程,参照国际船级社协会新编的《C型独立液货舱的屈服、屈曲和疲劳评估的有限元分析流程建议》(Recommendation No.174)的相关要求开展新颖构造货物围护系统有限元计算和可靠度分析方法研究,对新颖C型货物围护系统(双体罐和三体罐)进行应力分析和可靠性计算。采用可靠性的第一水准法构建新颖C型货物围护系统的设计衡准,并确定各分项系数,研究结果为制定符合可靠性标准的新颖C型货物围护系统规范和基于可靠性方法的结构强度准则提供参考。

HbA1c、LDL-C、HDL-C联合检测在2型糖尿病肾病中的诊断价值

目的:探究糖化血红蛋白(HbA1c)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)联合检测在2型糖尿病肾病中的诊断价值。方法:选取2019年1月—2021年12月南京中医药大学附属苏州市中医医院收治的120例2型糖尿病患者作为研究对象。根据患者是否发生糖尿病肾病将其分为合并肾病组(n=35)和未合并肾病组(n=85)。收集两组患者一般资料。检测两组Hb A1c、LDL-C、HDL-C。比较两组一般资料及Hb A1c、LDL-C、HDL-C水平。分析2型糖尿病肾病的危险因素。分析HbA1c、LDL-C、HDL-C对2型糖尿病肾病的诊断价值。结果:合并肾病组糖尿病病程长于未合并肾病组,吸烟史占比高于未合并肾病组,差异有统计学意义(P<0.05)。合并肾病组HbA1c、LDL-C水平均高于未合并肾病组,HDL-C水平低于未合并肾病组,差异有统计学意义(P<0.05)。logistic分析结果显示,HbA1c、LDL-C、吸烟史、糖尿病病程均是2型糖尿病患者合并糖尿病肾病的危险因素,HDL-C是保护因素(P<0.05)。HbA1c、LDL-C、HDL-C联合检测的AUC最高。结论:HbA1c、LDL-C、HDL-C联合检测应用于2型糖尿病肾病诊断中,具有较高的诊断价值,为临床对2型糖尿病肾病的早期诊断提供新思路。

达格列净对2型糖尿病病人肝脏脂肪含量及胱抑素C的影响

目的:比较使用达格列净+二甲双胍联合用药与单纯使用二甲双胍治疗对2型糖尿病病人肝脏脂肪含量(LFC)和胱抑素C(Cys C)水平的影响。方法:选取住院病人121例,按照治疗方案不同分为二甲双胍治疗组(甲组,n=51)和二甲双胍联合达格列净治疗组(乙组,n=70),所有病人均连续稳定使用上述治疗方案达半年以上,利用氢质子磁共振波谱法检测LFC,血清Cys C水平使用免疫比浊法进行检测,收集病人的一般人口学资料及实验室检测指标数据。分析不同实验室指标与LFC的关联,探讨不同治疗方式及其他实验指标对LFC和Cys C的影响。结果:2组病人的年龄、性别构成比、患病时长和体质量指数(BMI)的差异均无统计学意义(P>0.05);与甲组相比,乙组病人的LFC、血清Cys C水平、总胆固醇(TC)均明显降低(P<0.05~P<0.01),但三酰甘油(TG)和极低密度脂蛋白(VLDL)均升高(P<0.05);甲组的非酒精性脂肪肝(90.2%)比例高于乙组(30.0%)(P<0.01);相关分析结果发现,BMI、空腹血糖(FBG)和Cys C均与LFC存在关联(P<0.05~P<0.01)。以LFC为因变量,BMI、FBG、Cys C、病程、TC、TG和药物治疗作为自变量进行多元线性回归分析,发现与甲组相比,乙组可降低0.440个单位的LFC(P<0.01);同时以Cys C为因变量,BMI、FBG、LFC、病程、TC、TG和药物治疗作为自变量进行多元线性回归分析,与甲组相比,乙组联合用药能够降低0.689个单位的血清Cys C(P<0.01)。结论:二甲双胍联合达格列净能有效降低2型糖尿病病人LFC、血清Cys C水平,是LFC、血清Cys C的重要影响因素。

解剖锁定钛板及桡侧阻挡钛板治疗桡骨远端C型骨折的疗效

目的探讨解剖锁定钛板及桡侧阻挡钛板治疗桡骨远端C型骨折的疗效。方法将40例桡骨远端C型骨折患者按照治疗方法不同分为观察组(采用解剖锁定钛板及桡侧阻挡钛板治疗,20例)和对照组(采用单纯桡骨远端解剖锁定钛板治疗,20例)。记录两组术中骨折复位情况、术中出血量、手术时间、骨折愈合情况、掌倾角、尺偏角及腕关节活动度。结果患者均获得随访,时间2.5~6个月。术中观察组骨折断端均固定良好,对位对线满意,无桡侧骨块移位;对照组9例骨折复位及固定满意,11例存在不同程度的桡侧骨块移位。术中出血量、手术时间两组比较差异均无统计学意义(P>0.05)。两组骨折均愈合,时间10~12周。末次随访时,两组掌倾角比较差异无统计学意义(P>0.05);尺偏角及腕关节掌屈、背伸活动度观察组均大于对照组(P<0.05)。结论解剖锁定钛板及桡侧阻挡钛板治疗桡骨远端C型骨折,术中骨折复位简单,同时能有效减少桡侧骨块移位,更利于患者腕关节功能恢复。