Investigation and Application of Perforation Optimization Method on Shale Gas Horizontal Well with Numerical Simulation of Multicluster Fracturing under Dense-Segment Pattern.

Multicluster fracturing of horizontal wells has evolved into a mature and widely adopted technique for exploiting unconventional oil and gas fields. A well-designed multicluster completion strategy can yield an ideal fracturing outcome, significantly enhancing production rates and potentially delivering substantial economic benefits. Nevertheless, empirical evidence suggests that fractured horizontal wells frequently exhibit pronounced nonuniform production profiles, a prevalent issue stemming from the irregular geometry of propagated fractures. This issue critically constrains production rates. To mitigate the adverse effects of low-uniformity fracture propagation, it is imperative to elucidate the factors influencing uniformity levels and their corresponding patterns. Despite extensive discussions on hydraulic fracture propagation mechanisms and optional factors in hydraulic fracturing engineering, there exists a notable oversight regarding the optimization of perforation parameters to achieve improved fracturing uniformity during well completion procedures. This paper introduces an optimization method for perforation parameters based on a fully coupled pseudo-3D numerical model of multicluster fracturing. The impact patterns of cluster spacing, perforation number, and initial perforation diameter on multifracture propagation results and uniformity levels are thoroughly examined. The multicluster fracturing model, developed using the displacement discontinuous method (DDM), is coupled with material balance, pressure transmission, hole erosion computation, and initiation asynchrony estimation. To quantify the uniformity level of the fracturing result, the modified propagation uniformity index (Ufm) is employed. Simulation results from 20 cases are categorized into six groups based on varied changing patterns of perforation parameters, leading to the identification of five recommendations for optimizing perforation parameters. By implementation of the discussed optimized perforation parameters, successful fracturing outcomes were realized.

Design and Numerical Simulation Study of a Novel AICD for Water Control and Gas Production in Gas Wells.

The automatic inflow control device (AICD) used for water control and gas recovery in gas wells as the core component of gas well intelligent layered/segmented production and water control technology is very important for the development of advanced well completion (AWC) technology in water-producing gas reservoirs. Therefore, the design of AICD to ensure that the gas flows smoothly inside it and to keep water under control to a greater extent can maximize the performance of the AICD, and the most important thing is to restrict the water in the formation from entering the wellbore. However, currently, there are very few designs and research on the AICD used for water control and gas production in the gas wells, and the performance of this type of tool and the law of gas and water flow inside it are not perfect, so more in-depth research is needed. In this paper, a new type of AICD is designed to realize the function of water control and gas flow smoothly, and the DoE of the new AICD is carried out, determining the factors that will affect the key technical indicators and the factors that may have interactive effects, using the numerical simulation method of computational fluid dynamics to carry out optimal design, conducting fluid physical property sensitivity analysis, and flow rate applicability analysis. The results show that the tool is not sensitive to the viscosity of water and gas in different gas reservoirs but is very sensitive to the density of water and gas. When the gas/water flow rate ratio is less than 4, it can exert its water control effect. In addition, the results of multiple sets of physical experiments are well consistent with the simulation results; the average deviation of single-phase water is 10.91% and the average deviation of single-phase gas is 11.85%. Computational fluid dynamics and physical experiment results show that, under these conditions, the difference in fluid flow characteristics can be fully exploited; the channel is automatically identified to produce a small gas pressure drop and a large water flow pressure drop. The research in this paper belongs to the key technology of the AWC technology of gas wells in the new water control strategy of the current and has a certain reference value to make up for the defects of drainage gas recovery technology in the water management strategy..

Evaluation of the Release Mechanism of Sustained-Release Tracers and its Application in Horizontal Well Inflow Profile Monitoring.

The inflow profile is an important parameter to evaluate horizontal well productivity; however, quantitative interpretation of the inflow profile of the horizontal wells both accurately and cost-effectively is a common challenge faced by horizontal well production technology. The sustained-release chemical tracer is a new low-cost, long-lasting, and simple technique for monitoring the inflow profile in horizontal wells. In this study, a new type of sustained-release tracer is developed using bisphenol A-type epoxy resin as the polymer matrix and 2,6-difluorobenzoic acid, 3,4-difluorobenzoic acid, and 2,3,4,5-tetrafluorobenzoic acid as tracers. Meanwhile, the release mechanism and the influencing factors (chemistry of the tracer, temperature, salinity, and flow rate) of the sustained-release tracer are studied experimentally. The experimental results show that the release mechanism of the sustained-release tracer can be divided into two stages. The first stage involved the erosion process, in which the fluid gradually contacts and wraps the tracer, and the release rate is very fast. The second stage included the diffusion process, which is the diffusion-dissolution process once the fluid is completely wrapped around the tracer, and the release rate of this process is slow. The temperature is directly proportional to the release rate of the tracer, whereas salinity is inversely proportional to the release rate, and the fluid velocity does not affect the release rate. Finally, three kinds of sustained-release tracers are applied in the field, and a method to interpret the inflow profile of the sustained-release tracer is proposed. The result of application indicates that the sustained-release tracer developed in this study can efficiently monitor the inflow profile of the horizontal well.

A Novel Automatic Inflow-Regulating Valve for Water Control in Horizontal Wells.

Horizontal wells are prone to water coning and imbalanced inflow profile problems because of reservoir heterogeneity, the "heel-toe" effect, and different water avoidance heights. To solve these problems, an automatic inflow control device (AICD) technology is developed, as the traditional inflow control device (ICD) technology is frequently invalid after water breakthrough. In this study, a novel water control tool, an automatic inflow-regulating valve (AIRV), was designed to balance inflow profiles before water breakthrough and to limit water inflow after water breakthrough. With the use of a movable part, the AIRV can quickly distinguish fluids and limit the water output based on differences in fluid properties and the swirling flow principle. The water control efficiency and ability of the AIRV were simulated and optimized using computational fluid dynamics (CFD) software and verified experimentally using a water control testing system specially designed for the AIRV. We observed that (1) the total water force on the movable component of the AIRV is notably larger than that of oil because the swirling intensity of water is significantly higher than that of oil; moreover, the force directions of water and oil are opposite to each other. (2) The AIRV is sensitive to the flow rate and fluid viscosity but not to fluid density. (3) A higher water cut results in a higher AIRV pressure loss. The results of the CFD simulation and experimental test demonstrated that the AIRV has a significant water control ability and efficiency, particularly under conditions of a high production rate and high water cut. Thus, the AIRV can be used to enhance the control of water inflow before and after water breakthroughs in horizontal wells.

Correction to Flow Rate Profile Interpretation for a Two-Phase Flow in Multistage Fractured Horizontal Wells by Inversion of DTS Data.

[This corrects the article DOI: 10.1021/acsomega.0c02639.].

Flow Rate Profile Interpretation for a Two-Phase Flow in Multistage Fractured Horizontal Wells by Inversion of DTS Data.

The use of distributed temperature sensors (DTSs) has become a common practice in real-time downhole monitoring for horizontal wells in oil/gas reservoirs. However, great challenges still exist in translating measured DTS data to flow rate profiles due to lack of robust inversion approaches, especially for multistage fractured horizontal wells (MFHWs) with a gas-water two-phase flow. In this study, a comprehensive inversion system combined with a temperature prediction model and an inversion model has been developed to interpret flow rate profiles for MFHWs with a two-phase flow by inversing downhole DTS data. The temperature model serves as a forward model to predict temperature behaviors of MFHWs. The inversion model is derived from the Levenberg-Marquardt (L-M) algorithm to eliminate the errors between the measured DTS data and the simulated temperature profile. By simulating the temperature behaviors of two-phase flow MFHWs, it has been found that there exist abnormal decreases in the ΔT/x f ratio (temperature drop/fracture half-length) of the corresponding fractures with the production of water. According to this, two effective methods to diagnose water exit locations for an MFHW are introduced. Two synthetic cases are presented to illustrate the application of the inversion system in detail. Finally, a field application is analyzed and satisfactory inversion results are obtained. The maximum inversion temperature error is less than 0.03 K and the absolute error of the inversed gas production rate is less than 9 m3/day. The interpreted inflow rates of each stage are close to the measured data as well, which validates the reliability of the proposed inversion system. The findings of this study provide a promising tool to interpret flow rate profiles for an MFHW with a two-phase flow.

Pd-Catalyzed Enantioselective Syntheses of Trisubstituted Allenes via Coupling of Propargylic Benzoates with Organoboronic Acids.

Enabled by the newly developed ligand, Ming-Phos, the first example of palladium-catalyzed highly enantioselective coupling of racemic propargylic benzoates with organoboronic acids for chiral allenes synthesis has been developed. Excellent asymmetric induction has been achieved with a decent substrate scope. Synthetic potentials for the construction of polycyclic compounds with multiple chiral centers have been demonstrated.

Efficacy and safety of rituximab in the treatment of membranous nephropathy: A systematic review and meta-analysis.

BACKGROUND AND OBJECTIVES: Rituximab (RTX) is considered to be a promising drug for curing membranous nephropathy. However, the efficacy and safety of RTX in treating membranous nephropathy remain uncertain. This meta-analysis aimed to investigate the efficacy and safety of RTX in patients with membranous nephropathy. METHODS: A literature search was performed using Pubmed, Embase, OVID, and Cochrane Library and randomized controlled trials (RCTs) case-controls and cohort studies published till 30 July 2019 were assessed. The studies assessing the efficacy and safety of RTX in patients with membranous nephropathy were included. RESULTS: Eight relevant trials involving 542 patients were included in the meta-analysis. It was found that RTX did not significantly improve serum albumin levels and e-GFR when compared with the control group (including cyclosporine and cyclophosphamide, chlorambucil, prednisone, non-immunosuppressive anti-proteinuria treatment), serum albumin levels (OR = 0.31, 95%CI-0.12-0.74, P = .15), e-GFR (OR = -1.49, 95%CI-17.14-14.17, P = .85). However, RTX did reduce the serum creatinine (OR = -0.01, 95%CI-0.36-0.34, P = .95) and urinary protein (OR = -2.39, 95%CI -7.30 -2.53, P = .34) levels. Also, in comparison to the control group, RTX did improve the total remission rate (OR = 1.63, 95%CI 0.48-5.54, P = .43), achieve a higher rate of complete remission (OR = 2.54, 95%CI 1.65-3.90, P < .01) and also reduced the amount of M-type phospholipase A2 receptor-Antibody depletion in patients (OR = 5.59, 95%CI 1.81-17.2, P = .003). RTX-related adverse events were mostly mild (most infusion-related reactions) in nature and serious adverse events were rare. CONCLUSION: RTX proved to be efficient, well-tolerated and a safe drug in the treatment of membranous nephropathy. Most patients reach complete remission during the follow-up period, and relapse is rare. RTX may turn out to be promising in membranous nephropathy patients.

Tri(o-tolyl)phosphine for highly efficient Suzuki coupling of propargylic carbonates with boronic acids.

A highly efficient catalytic system consisting of Pd2(dba)3·CHCl3 and tri(o-tolyl)phosphine has been identified for the coupling of propargylic carbonates with different types of organo boronic acids at room temperature. Excellent central-to-axial chirality transfer was also demonstrated.

A catalytic highly enantioselective allene approach to oxazolines.

Oxazolines are a very important class of heterocyclic compounds. However, catalytic enantioselective syntheses are very limited. Here, a highly enantioselective palladium-catalyzed coupling-cyclization of readily available N-(buta-2,3-dienyl) amides with aryl or 1-alkenyl iodides has been developed for the asymmetric construction of oxazoline derivatives. Many synthetically useful functional groups are tolerated in this reaction. The absolute configuration of the chiral center in the products has been established by X-ray diffraction study. A model for prediction of the absolute configuration of the chiral center in the products from this cyclic enantioselective nucleophilic allylation has been proposed. The synthetic potentials based on the unique structure of the products formed have also been demonstrated.

Enantioselective double manipulation of tetrahydroisoquinolines with terminal alkynes and aldehydes under copper(I) catalysis.

Tetrahydroisoquinoline alkaloids with a C1 stereogenic center are a common unit in many natural and non-natural compounds of biological importance. Herein we describe a novel Cu(I) -catalyzed highly chemo- and enantioselective synthesis of chiral tetrahydroisoquinoline-alkaloid derivatives from readily available unsubstituted tetrahydroisoquinolines, aldehydes, and terminal alkynes in the presence of the ligand (R,R)-N-pinap. This synthetic operation installs two substituents in the 1- and 2-positions.

Bimetallic enantioselective approach to axially chiral allenes.

An efficient bimetallic Zn(II)/Cu(I)-mediated asymmetric synthesis of simple axially chiral allenes from terminal alkynes and aldehydes was realized by taking advantage of the chiral amine (S)-α,α-diphenylprolinol 3. This one-pot procedure is compatible with broad scopes of both terminal alkynes and aldehydes, providing axially chiral allenes in practical yields with an excellent enantioselectivity. Control experiments revealed that CuBr is responsible for the efficient formation of propargylic amine while the combination of CuBr and ZnBr2 plays crucial roles in the amine-to-allene transformation.

Highly enantioselective relay catalysis in the three-component reaction for direct construction of structurally complex heterocycles.

A highly enantioselective three-component cascade reaction, consisting of an enantioselective [4+2] cycloaddition reaction catalyzed by chiral phosphoric acid and a subsequent catalytic intramolecular hydroamination by gold(I) complex, provides a unique method to access structurally diverse julolidine derivatives in high optical purity.