压力保持系统中一口井的压力恢复分析

The development and application of a new solution is demonstrated for the type-curve analysis and interpretation 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 superposition. 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.     

Performance enhancement of water bath heater at natural gas city gate station using twisted tubes

Natural gas is transported from producing regions to consumption regions by using transmission pipelines at high pressures. At consumption regions, the pressure of natural gas is reduced in city gate stations(CGSs). Before the pressure reduction process, the temperature of natural gas is increased usually by using a water bath heater,which burns natural gas as fuel, to protect against freezing of natural gas. These types of heat exchangers have a low efficiency and consume a lot of fuel to generate the required heat. In the current study, the twisted configuration of the heating coil is proposed and investigated to enhance the heat transfer through a water bath heater with a nominal capacity of 1000 m~3·h~(-1). Firstly, the implementation procedure is validated with data collected from the CGS of Qaleh-Jiq(located in Golestan province of Iran). A very good agreement is achieved between the obtained results and the real data. Then, three different twist ratios are considered to examine the twisting effects. The proposed technique is evaluated in the terms of velocity, temperature, and pressure variations, and the results are compared with the conventional case, i.e. straight configuration. It is found that both the heat transfer rate and the pressure drop augment as the twist ratio is raised. Finally, it is concluded that the twisted tubes can reduce the length of the gas coil by about 12.5% for the model with low twist ratio, 18.75% for the model with medium twist ratio, and 25% for the model with high twist ratio as compared to the straight configuration.     

加长循环流化床提升管中加速段长度的实验研究

Systematic experimental work was conducted to investigate the solid acceleration length in a 16 m long circulating fluidized bed riser with fluid cracking catalyst particles over a wide range of operating conditions. A more feasible method is proposed to determine the acceleration length from the measured axial profiles of pressure gradient (or apparent solid holdup). With this new method and large amount of experimental data, a clear picture on the variation of the acceleration length with both solid circulating rate and superficial gas velocity is obtained.It is found that the acceleration length increases generally with increasing solid flow rate and/or decreasing gasvelocity. However, the trend in variation of the acceleration length with operating conditions are quite different in different operation ranges. Reasonable explanations are suggested for the observed variation patterns of acceleration length.     

The Measurement of Oil, Gas and Water Flowrates in Three-Phase Slug Flow

Three-sphase flow invo1ving oil-water two immiscible liquids and gas which is often foundin the fields of petroleum production has been studied in this paper.A new method with thecombination of a horizontal tube,a downward flow vertica1 tube and an orifice to measure theflowrates is presented.In this method the frictional pressure drop in the downward vertical tube isreplaced by that in the horizontal tube,the void fraction is derived from the gravitational pressuredrop,then the volume fraction of the individual phase can also be obtained.The individual flowratescan be calculated when the water fraction is known.This method is applicable for many kinds ofoil-wells to measure the flowrates of crude oil,natural gas and water.Compared with other methods,the presented method involves fewer measuring parameters.The experimental results proved quitegood accuracy of the method,with measurement deviation within 10%,and reliable results wereobtained under high Dressure conditions.     

The Solubility of Styrene from Polystyrene in Supercritical CO2

The solubility of styrene from polystyrene in supercritical carbon dioxide is measuredat 323 K,333 K,and 343 K in the pressure range from 12 to 28 MPa.Based on the associationconcept and the theory of dense gas sorption in polymers,a displacement and association mechanismon supercritical fluid extraction of the monomer from the polymer is proposed.And,a novel math-ematical model for correlating the solubility data obtained from the experiments is also proposed inthe paper.     

PNEUMATICALLY CONTROLLED MULTI-STAGE FLUIDIZED BED AND ITS APPLICATION IN SOLVENT RECOVERY FROM A PLANT WASTE GAS

The downcomer is the key component of a multi-stage fluidized bed.A pneumatically controlleddowncomer has been devised,consisting of a fully fluidized dipleg followed by a conical spout for upwarddischarge in dense phase.Such a design has been found to insure against bridging of solids in descent andagainst spouting of solids from a lower layer caused by gas by-passing.In experimental investigations,flow characteristics are measured including the pressure drops of thedifferent fluidized beds and of the downcomers for various gas and solids flow rates as well as the solidsresidence time distribution,operating either with a multiplicity of gas sources for the various downcomersor with only two gas sources.In a particular design,a multi-stage ftuidized bed with dual gas supply,inwhich one half is incorporated centrally in the other,has been tested on pilot scale for recovering solventfrom low concentration ethylene dichloride streams of a plant waste gas.Main test results obtained wereas follows:adsorption rate>97%concentration of waste gas<25 mg/m~3active carbon loss<0.1%This kind of conical downcomer in which the solids arc either transported from a high- to a low-pressure region,or from a low- to a high-pressure region,is also used to control the solids discharge ofcyclone diplcgs or the feeding and discharging in other solids circulation systems.     

The Solubility of Styrene from Polystyrene in Supercritical CO2

The solubility of styrene from polystyrene in supercritical carbon dioxide is measured at 323 K, 333 K, and 343 K in the pressure range from 12 to 28 MPa. Based on the association concept and the theory of dense gas sorption in polymers, a displacement and association mechanism on supercritical fluid extraction of the monomer from the polymer is proposed. And, a novel mathematical model for correlating the solubility data obtained from the experiments is also proposed in the paper.     

基于实验等温线确定超临界气体绝对吸附量的数学方法

A mathematical method was proposed for the determination of absolute adsorption from experimental isotherms. The method is based on the numerical equality of the absolute and the excess adsorption when either the gas phase density or the amount adsorbed is not quite considerable. The initial part of the experimentalisotherms, which represents the absolute adsorption, became linear with some mathematical manipulations. The linear isotherms were reliably formulated. As consequence, either the volume or the density of the supercritical adsorbate could be determined by a non-empirical way. This method was illustrated by the adsorption data of supercritical hydrogen and methane on a superactivated carbon in large ranges of temperature and pressure.     

An experimental approach for measuring carbon dioxide diffusion coefficient in water and oil under supercritical conditions

Several direct or indirect approaches have been proposed to measure diffusion coefficient of gases into liquids. The main complexity of indirect techniques such as pressure decay method is interpreting early pressure–time data which strongly affected by incubation period effect or convective instability. In the current approach, accurate apparatus and precise experimental setup including a high pressure and temperature PVT cell, a high precision Sanchez pump, heating and recording sub-system are implemented and a novel data analysis procedure is applied to modify pressure decay method. The effect of incubation period is reduced remarkably and diffusion coefficient of carbon dioxide in water in wide range of pressures and temperatures is determined and the effects of temperature, pressure and carbon dioxide phase alteration from gas to supercritical are investigated and the value of uncertainty is estimated.Furthermore, diffusion coefficient of CO_2 and methane in an oil sample from one of the Iranian southwest oil formations is determined precisely using the experimental approach while no incubation period is detected. The results showed that incubation period duration decreases with increasing diffusion coefficient. Additionally, when CO_2 state is gas, rate of increasing diffusion coefficient with pressure is decreased with temperature and when CO_2 state is supercritical, the rate of increasing diffusion coefficient with pressure is decreased significantly.     

A METHOD FOR CALCULATING THE EXTENT OF REACTION OF SOLID PARTICLES WITH FLUID IN COMPLETELY MIXED REACTORS CONNECTED IN SERIES

When solid particles react with a fluid,the overall rate is influened by the fraction of the solidunconverted as well as by the operating conditions such as temperature and pressure.Calculation of solidsconversion in the individual reactor of a multi-stage reactor system has therefore to be based upon thesolids residence time distribution (RTD) in the respective stages.By using either the Dirac function δ(0) or the probability density function of the sum of independentrandom variables,the solids RTD in any stage of completely mixed reactors connected in series with nointerstage backflow has been obtained.The latter method has also been used in deriving general formu-las for the calculation of solids conversion when the order of chemical reaction is simple.For complexchemical reaction rate equations a stagewise procedure for numerical computation is proposed,and twocases are discussed according to whether the rate equation is expressed in its integral or differential formrespectively.     

松南气田气井合理产量模式建立

松南气田开采层位为火山岩储层,受构造和火山活动的双重控制,非均质性强,连通性差,而且有边底水,现有的经验难以满足开发需要。目前松南气田已投入开发,如何确保火山岩储层气藏高效开发,首先要解决气井合理产量确定问题。针对松南气田火山岩储层的特点,对不同类型的气井开展试井工作,利用试井成果确定气井的产能方程。松南气田火山岩储层气井在生产上表现为产气量差别大、压力下降快慢不同,因此,在单井合理产量模式确定上,主要是以气井产能方程为基础,考虑气井的边底水特征、井筒积液、稳产期等因素,对不同类型的气井分别建立了合理产量模式。     

气井产量递减分析方法应用

确定气藏参数的方法常常是关井测压。然而,我国有许多气藏渗透率特别低,压力恢复所需的时间特别长,有时长达几个月。因此,有必要研究根据气井生产史确定气藏参数的方法,避免关井给生产带来的损失。本文对具有生产记录的气井,采用现代产量递减分析方法反求地层参数,并用标准化时间和标准化压力半对数图,作为检验计算结果正确与否的标准。实例对比表明,对于没有关井测压的气井,可以用该方法反求气藏参数。     

老井侧钻技术发展前景分析

老井侧钻是提高单井产量、开发剩余油气藏的有效手段,可以大幅度降低投资成本的同时提高采收率。随着国内外油田对老井侧钻技术的应用日益增多,暴露了一些侧钻的难点,应该根据不同油气田的实际情况筛选合适的老井进行侧钻。     

低渗透气藏应力敏感性的试验研究

由于低渗透油气田的开发过程中,存在着应力敏感问题,这严重影响了低渗透油气田的有效开发。本文通过对苏里格气田的12块岩心进行的室内实验研究,获得了多种应力敏感曲线,总结了低渗透储层应力敏感性变化规律,同时在此基础上,利用气藏工程的不稳定分析方法对该气田几口典型井的生产历史进行拟和后分析,进一步验证应力敏感随气田开发产生的变化规律,并结合实际情况对该区的生产开发提出一些合理的建议。     

纯油区薄差油层和表外储层试井解释方法分析与认识

X区纯油区二、三次井主要开采有效厚度小于0．5m的表内薄差储层和表外储层,岩芯资料统计结果表明,平均有效孔隙度18．12％,平均有效渗透率74．0×10^3μm2从试井解释统计结果看,关井时间72h内出现径向流的井仅占11。05％。根据X区纯油区二、三次井开发现状,应用目前采用的试井解释方法,对出径向流直线段的井应用水驱平均压力进行地层压力水平分析,受解释参数的影响,地层压力偏低0．61MPa,采用合理参数计算的地层压力值与注采比的关系符合油田开发规律。建议今后应用产液剖面综合分析出液厚度,并考虑砂体发育情况编制软件精确计算单井的实际供油面积,提高地层压力的解释精度;不出径向流直线段井采用关井末点压力分析地层压力水平,在关井时间短的条件下,该压力不能真实反映实际的地层压力水平。由于受产量任务影响,不能无限延长关井时间,因此有必要针对薄差油层和表外储层试井资料出径向流直线段井数比例低的现状,探索压力恢复有效测试时间,并研究应用试井早期资料进行试井解释的方法,以更好地进行储层评价和指导生产。     

The interpretation of DST data for donghae-1 gas field, block VI-1, Korea

Donghae-1 gas field is located in Ulleung basin at offshore Ulsan, Korea, and its recoverable reserve is expected to be 170 to 200 BCF (Billion cubic feet). The field was confirmed to have potential gas and condensate reserves from an exploration well in 1998 and two appraisal wells in 1999. This field consists of five zones, with an average reservoir depth of about 7,000 to 8,000 ft. In this study, we have performed an analysis of Gorae V DST (Drillstem test) #2 for testing B4 zone which has the biggest reserves and Gorae V-1 DST #2 for testing B3 and B4 zones simultaneously among DST data achieved in a total of 11 zones at three wells. The pressure and flow rate recorded from two tested zones were used to obtain the reservoir characteristics and the well productivity. For pressure transient test data, we carried out the analysis of reservoir permeability, skin factor, wellbore storage effect and barrier effect by using the Homer plot and type curve matching methods. Also, with the deliverability test data, we estimated the absolute open flow which is the maximum flow rate of the gas well, and extracted the correlations representing production rate with reservoir pressure. According to the analysis, Gorae V DST #2 of B4 zone has a permeability and skin factor of 37 md (Millidarcy), 4.54, and Gorae V-1 DST #2 of B3 and B4 zones has 23 md and 21.0, respectively. It was also found that the wellbore storage effect was not significant for the two wells tested. From the deliverability test analysis, the AOF (Absolute open flow) of the Gorae V DST #2 is 152.8 MMSCFD (Million standard cubic feet per day), and that of the Gorae V-1 DST #2 is calculated to be 68.2 MMSCFD.     

靖边气田新增探明储量区块马五1+2气藏特征

靖边气田新增探明储量区块实测地层压力资料与气层中部海拔进行拟合回归相关性较好,其压力梯度与气田本部压力梯度值很接近.新增储量区块内无论是天然气组份,还是相对密度与靖边气田本部都有明显的一致性,表现了同一气藏的特征.通过气藏流体性质和试气结果的分析,按照气井不同产量分为Ⅰ类、Ⅱ类、Ⅲ类井分别进行评价.对比本次新增探明储量区块与已探明面积内投产井配产指标发现,二者不同类型气井井数比例一致,单井平均无阻流量及平均配产产量也接近.     

Optimizing the location of the gas injection well during gas assisted gravity drainage in a fractured carbonate reservoir using artificial intelligence

Gas assisted gravity drainage (GAGD) is a novel subdivision of gas injection method. In this method the injection wells are located in the upper bed of the oil zone, and the production wells are drilled at the bottom bed of the oil zone. Reservoir simulation is among the decision tools for investigating production rate and selecting the best scenarios for developing the oil and gas fields. Selecting the location of the injection wells for reaching the optimized pressure and production rate is one of the most significant challenges during the injection process. Recent experiences have shown that artificial intelligence (AI) is a reliable solution for taking the mentioned decision appropriately and in a least possible time. This study is attributed to the investigation of applying the artificial neural network (ANN) as an artificial intelligence method and a potent predictor for choosing the most proper location for injection in a GAGD process in a fractured carbonate reservoir. The results of this investigation clearly show the efficiency of the ANN as a powerful tool for optimizing the location of the injection wells in a GAGD process. The comparison between the results of ANN and black oil simulator indicated that the predictions obtained from the ANN is highly reliable. In fact the production flow rate and pressure can be obtained in every possible location of the injection well.     

DN—A、DN—B井生产阶段环空压力诊断分析

迪那气田属高温、超高压凝析气藏,在开发生产过程中,部分单井,如DN—A、DN—B井,典型地表现出生产套压和技术套压异常的现象,这严重影响着这些井的安全正常生产。当前国内外还没有形成一套针对高温高压气井环空压力诊断分析的方法。结合塔里木油田实际情况,首先分析压力来源并结合API—RP90标准计算各环空的最大许可工作压力;其次密切关注生产动态,及时发现生产出现异常的情况;三是现场通过环空放压手段,结合放出物质的各种性质分析井下管柱的完整性,同时排查井口设备安全隐患,最终得出气井套压出现异常的原因。