准噶尔盆地高探1井管壁沉淀物的组成与沉积机理分析

准噶尔盆地高探1井生产过程中,油管内壁形成大量黑色固体状沉淀物,严重影响生产。针对以上问题,采 用三氯乙烯对井壁内沉淀物的不同部位进行了有机物和无机物提取,表征了有机物和无机物的组成,分析了无 机物对原油吸附和沉积的影响,进一步探明了沉淀物的形成机理。结果表明,有机和无机成分含量相差较大,沉 淀物中心的无机物含量达到71.51%,而分散在表面颜色较深的部位仅为16.55%;不同部位有机物的族组分含量 却相近,其中沥青质占比为52.71%～58.37%。侧链长度大、支化程度高的沥青分子缔合体更易沉积。沉淀物中 的无机物主要为硫酸钡,其具有的片层状结构表面粗糙,加大了对沥青质的吸附。高探1井沥青垢的沉积机理为 1～20 μm的片层状硫酸钡等无机颗粒吸附原油中侧链长度大、支化程度高的沥青分子缔合体,聚集为20～100 μm的大颗粒堆积体,共同形成沉淀物黏附于管壁造成管柱堵塞。     

四棵树凹陷高探1井流体特征及油藏类型分析

利用气相色谱法对高探1井分离气和分离油进行了油气组成分析。开展高探1井地面原油特性研究,并运用高温高压地层原油分析仪对高探1井地层流体高压物性特征进行了深入研究。结果表明,高探1井地层流体中C1—C5组分含量达71.41%,轻质烃含量较高,重质成分含量低,含蜡量中等、密度低、黏度低、凝固点中等,具有挥发性油的特征。地层原油在地层条件下为单相液态流体,地层异常高压,地饱压差大,地层能量充足,地层油体积收缩率较高,弹性能量较强。结合地层流体高压物性数据,利用储集层流体三元组成三角图、油气藏判别参数(φ_1)综合判断,初步认为高探1井的油藏类型为低饱和挥发性油藏。     

注天然气油井沥青质析出规律研究

目的 解决东河区块原油在注气开采过程中沥青质沉积堵塞井筒问题.方法 采用高温高压固相沉积规律测试装置,基于光散射理论,研究了温度、压力、气油比等因素对沥青质析出特征的影响.结果 温度升高会增加沥青质在原油中的溶解度,促进原油稳定;等温降压过程中,沥青质随着压力降低逐渐析出,在泡点压力附近达到最大析出量,发生沥青质沉积堵...     

准噶尔盆地南缘井筒堵塞物中沥青质分子组成研究

采用傅里叶变换离子回旋共振质谱分析技术,分析了准噶尔盆地南缘高探1井原油及井筒堵塞物抽提物中沥青质化学组成及差异,探讨了沥青质的组成及结构与沥青质沉积关系,对于沥青质聚集理论研究具有重要意义.研究结果显示,高探1井原油及井筒堵塞物抽提物中沥青质分子主要为N1、N1 O1、O1、O2、O3和O4类化合物,但堵塞物抽提物中...     

海相古油藏及可溶有机质再生烃气能力研究

通过大量样品的封闭体系热压模拟实验,对比研究了不同性质、不同组成海相古油藏及可溶有机质热裂解再生烃(气)能力及其产率分布特征。结果表明,不同海相古油藏与可溶有机质的再生烃气能力大小为:凝析油>轻质油>正常原油>志留系沥青砂岩≥稠油≥低成熟固体沥青≥含沥青灰岩>稠油油砂>氧化固体沥青;其再生烃气能力除与岩性、赋存状态、演化程度等有关外,主要受所含可溶有机质性质和组成的制约;可溶有机质再生烃过程是干酪根生烃的延续,其生烃气潜力与干酪根烃源岩相当,当其达到高过成熟阶段时,可以作为新的轻质油气或者天然气来源。      

元坝高含硫气田井筒堵塞物分析

元坝气田是国内目前埋藏较深、开发难度较大的酸性大型海相气田,开采过程中井筒堵塞现象时有发生。为了明确堵塞物主要组成,采用热重分析、扫描电镜、X射线衍射、高温模拟蒸馏碳数分布分析等方法,对井筒堵塞物成分以及堵塞物来源进行分析。结果表明,H1井堵塞物主要以沥青质类有机组分为主,H2井堵塞物则主要以FeS_2、BaSO_4等无机组分为主,H3井堵塞物主要是BaSO_4、CaCO_3、少量的S单质和SiO_2。元坝地区不同气井之间的堵塞物存在一定的差异,沥青类有机组分主要来源于地层析出沥青和入井流体高温热解产物,无机堵塞物出现与地层出砂、重晶石等添加剂有关。     

深水高温高压油气生产致井口抬升预测研究北大核心CSCD

深水高温高压井油气开发过程中,由于油气流将井底热量携带至井口,容易出现井口抬升现象,可能导致井口装置密封失效,存在较大的安全隐患。为提高深水油气田开发井全寿命周期的完整性,针对深水高温高压井油气开采阶段,建立了深水高温高压油气开发井筒温压场及井口抬升高度计算模型,并基于自主研制的高温高压油气开发井口抬升模拟实验装置,开展了不同工况条件下的井口抬升模拟实验研究。研究结果表明:井筒温度升高及其引发的圈闭压力是造成井口抬升的两大主要因素;本文建立的模型计算结果与实验数据相对误差小于10%,可用于预测不同工况条件下的井口抬升高度。本文研究结果对于优化固井及地面管线设计、提高深水高温高压井井口完整性具有较好的指导意义。     

深水高温高压油气生产致井口抬升预测研究

深水高温高压井油气开发过程中,由于油气流将井底热量携带至井口,容易出现井口抬升现象,可能导致井口装置密封失效,存在较大的安全隐患。为提高深水油气田开发井全寿命周期的完整性,针对深水高温高压井油气开采阶段,建立了深水高温高压油气开发井筒温压场及井口抬升高度计算模型,并基于自主研制的高温高压油气开发井口抬升模拟实验装置,开展了不同工况条件下的井口抬升模拟实验研究。研究结果表明:井筒温度升高及其引发的圈闭压力是造成井口抬升的两大主要因素;本文建立的模型计算结果与实验数据相对误差小于10%,可用于预测不同工况条件下的井口抬升高度。本文研究结果对于优化固井及地面管线设计、提高深水高温高压井井口完整性具有较好的指导意义。     

泥页岩不同介质中可溶有机质组成差异性及对页岩油富集的意义

泥页岩中的有机质组成复杂,其差异性对于认识油气的生排烃和页岩油气的形成与富集机理具有重要意义。选择南襄盆地泌阳凹陷始新统核桃园组湖相泥页岩为研究对象,系统对比了其中不同介质（包括无机矿物和有机干酪根）中可溶有机质的组成与差异,并与页岩油和砂岩油相对比,分析差异性,讨论其地质地球化学意义。结果表明,泥页岩不同介质中可溶有机质的饱和烃组成差异性较小,难以区分,反映了页岩油气的源内生排烃过程,饱和烃自身各种化合物之间的极性差异不大;而芳烃组成差异明显,其中,有机介质中可溶有机质的芳烃组成与页岩油/砂岩油相当,而无机介质中可溶有机质的芳烃组成与页岩油/砂岩油差异较大,反映了油气生排烃的过程。据此,泥页岩在初次运移的排烃过程中,生成的烃类物质首先充满无机矿物基质孔隙,并满足矿物颗粒表面吸附后,进入烃源层内微裂缝和/或砂岩夹层而富集,这类油气资源即目前所谓的页岩油。      

中国中、新生代陆相盆地中有机质的热演化

本文根据生油岩中可溶有机质饱和烃及其重组分——沥青质和不溶有机质干酪报等资料,深入研究了我国中、新生代不同类型沉积盆地有机质随埋深的热演化特征,在此基础上提出了有机质及原油热演化过程六个阶段的划分。通过有机元素、红外、色谱、色谱-质谱联用、顺磁等资料,研究了各热演化阶段有机质的结构组成变化,进一步探索了油气的生成机理和过程。     

高压注烃类气体过程中沥青质初始沉淀压力试验研究

为预防注烃类气体提高采收率过程中产生沥青质沉淀,对沥青质初始沉淀压力进行了试验研究.在分析注烃类气体过程中沥青质沉淀机理的基础上,通过自主研发的固相沉积激光探测装置,采用透光强度法测定了原油样品在不同温度下高压注气过程中沥青质的初始沉淀压力,并确定了沥青质沉淀的深度.试验得出,原油沥青质初始沉淀压力随温度升高而下降,测得44,80和123 ℃温度下原油的沥青质初始沉淀压力分别为44.1,39.7和35.2 MPa;每注入物质的量分数为1%的烃类气体,试验油样的沥青质初始沉淀压力升高0.5~0.6 MPa;井筒温度压力曲线与沥青质沉淀相包络线相结合预测井筒中出现沥青质沉淀的深度在1 800 m左右,与现场情况吻合较好.研究表明,原油中沥青质初始沉淀压力与注气量之间呈线性关系,可为现场注气驱油预防和清除沥青质沉积物提供理论依据.      

注气对固溶物沉淀影响的研究与应用

注气采油是提高原油采收率的主要方式之一,在此过程中准确描述含有沥青质等高分子有机固相物质的油气体系相平衡十分必要。为此,将沉淀的沥青质视为固相,假设标准状态下必须有沥青质沉淀,将标准状态压力和温度引入沥青质固相逸度计算,并同时考虑了标准状态压力和温度对沥青质固相逸度的影响,建立了能模拟沥青质沉淀的气、液、固三相相平衡热力学模型。据该模型计算的结果表明:①能通过比较液相沥青质逸度和固相沥青质逸度大小来判断固相沥青质沉淀的出现。②当注入某油的气体为烃类混合气体时,烃类混合气体的添加使得含沥青质原油的组分发生变化;温度相同时,注气浓度越高,沉淀的压力越大;浓度相同时,温度越低,沉淀的压力越大;当沉淀量一定时,随着注气浓度增加,油品的饱和压力随之增大;相同注气浓度下,当压力高于饱和压力时,随着压力增大,沉淀量减少。③在温度不变的情况下,注入某油的气体为CO2时,其沥青质沉淀量是注CO2浓度的函数且随着CO2浓度的增加,固相(沥青质)的沉淀量不断增大。④在注气驱油过程中,气体的注入极易引发含沥青质原油中沥青质等重质有机物的沉积。     

Experimental and numerical modeling of sulfur plugging in carbonate reservoirs

Sour gas, mainly in the form of hydrogen sulfide, is produced in large amounts from many oil and gas reservoirs in the United Arab Emirates. In addition to creating problems in production lines, the precipitation of elemental sulfur in vicinity of the wellbore is often reported to cause wellbore damage. While there have been several studies performed on the role of solid deposition in gas reservoirs, the role of sulfur deposition in oil reservoirs has not been investigated. This paper presents experimental results along with a comprehensive wellbore model that predicts sulfur precipitation as well as plugging. Two separate sets of experiments, one for a gas phase system and another for a crude oil system, were conducted to investigate the deposition of elemental sulfur in (linear) carbonate cores. The gas flow tests were conducted with elemental sulfur being carried with nitrogen through limestone cores. Changes in gas flow rate were monitored while the injection pressure was held constant. A series of experiments generated valuable data for plugging with elemental sulfur. X-ray diffraction tests provided evidence of sulfur deposition along the cores. The oil flow tests were carried out to observe sulfur precipitation and plugging in a carbonate core. The crude oil was de-asphalted before conducting these tests in order to isolate the effect of asphaltene plugging. Significant plugging was observed and was found to be dependent on flow rate and initial sulfur concentration. This information was used in a phenomenological model that was incorporated in the wellbore numerical model. The data for the numerical model were obtained from both test tube and oil flow experiments. By using a phenomenological model, the wellbore plugging was modeled with an excellent match (with experimental results).     

Effect of pressure of the onset of asphaltene precipitation during gas flooding

In order to prevent and eliminate the asphaltene precipitation during gas flooding, the rules of the changes of the pressure under different conditions are systematically studied by the laser solid detection system, the light transmission method, and the P–T phase diagram when the asphaltene precipitation occurs. When the pressure is reducing to a certain value, the penetrating light intensity of the crude oil is markedly decreased, which shows that the pressure at this point is the pressure of the onset of asphaltene precipitation (AOPP). The AOPP value decreases with an increase in the temperature. During gas flooding, the AOPP value increases with an increase in the content of gas in the crude oil, and these two nearly do have a linear relationship. According to the P–T phase behaviors of the gas–crude oil system, with an increase in the content of gas in the crude oil, the asphaltene precipitation envelope curve (APE) is gradually moved up, which shows that the possibility of asphaltene precipitation is much higher. During oil production, for the oil reservoirs with rich asphaltene, the production pressure drop should be kept a small value to ensure that the flowing bottom-hole pressure is higher than AOPP and it is necessary to help complement producing energy timely by using water injection, gas injection, etc. Besides, according to the intersection of T–P curve and APE curve in the P–T phase diagram, the location where the asphaltene precipitation occurs in the wellbore can be roughly predicted. The experimental results can provide the theoretical foundation for taking measures to prevent and eliminate the asphaltene precipitation.     

Deposition and flocculation of asphaltenes from crude oils

A crude oil has four main constituents: saturates, aromatics, resins, and asphaltenes. The asphaltenes in crude oil are the most complex and heavy organic compounds. The classic definition of asphaltenes is based on the solution properties of petroleum residuum in various solvents. Asphaltenes are a solubility range that is soluble in light aromatics such as benzene and toluene, but are insoluble in lighter paraffins. The particular paraffins, such as n-pentane and n-heptane, are used to precipitate asphaltenes from crude oil. Deposition of asphaltenes in petroleum crude and heavy oil can cause a number of severe problems. The precipitation of asphaltene aggregates can cause such severe problems as reservoir plugging and wettability reversal. Asphaltenes can precipitate on metal surface. Cleaning the precipitation site as well as possible appears to slow reprecipitation. To prevent deposition inside the reservoir, it is necessary to estimate the amount of deposition due to various factors. The processes can be changed to minimize the asphaltene flocculation, and chemical applications can be used effectively to control depositions when process changes are not cost effective. Asphaltene flocculation can be controlled through better knowledge of the mechanisms that cause its flocculation in the first place. The processes can be controlled to minimize the asphaltene flocculation, and chemical applications can be used effectively to control depositions when process changes are not cost effective.     

Study of Asphaltene Precipitation Using Refractive Index Measurement

The measurements of the refractive index of crude oils were utilized in this work to enhance the understanding of the behavior of asphaltenes in crude oil, specifically, their tendency to precipitate from crude oil. The onset of asphaltene precipitation was measured in eight crude oil samples, which were titrated with either heptane or pentane in order to induce precipitation of the asphaltenes. The refractive index of each sample was measured to find its relationship to asphaltene precipitation. The assumption that refractive index of a mixture is a linear combination of the refractive indexes of the individual components was verified. It was also found that mixtures of heptane or pentane and crude oil also followed this same behavior. However, as asphaltenes began to precipitate from the solution, the refractive index no longer followed this linear mixing rule. Careful analysis of the refractive index data for each of the crude oil samples revealed many interesting relationships between the refractive index data and the content of the different polar asphaltene fractions present. The refractive index of asphaltenes was predicted from the refractive index data of crude oils. The results suggest the possibility predicting the properties and characteristics of the asphaltenes contained in a crude oil simply by measuring the refractive index.     

轮南桑解油田稠油化学降黏新工艺

轮南、桑解油田部分储层原油沥青质含量高,生产过程中沥青质析出,造成井筒举升困难及地面集输管线超压,导致油井无法正常生产。为了解决上述问题,通过室内研究与现场试验,研发了一种耐高温、抗高矿化度的水溶性稠油降黏剂JN-1,并设计了3种针对不同油井管柱、原油物性特征的药剂加注工艺。该稠油化学降黏工艺解决了高温、高矿化度条件下高沥青质含量原油的井筒举升及地面集输困难的问题,实现了油井连续生产,现场应用14井次,累计增油16037t,累计增气257×10⁴m³。稠油化学降黏新工艺的现场应用效果明显,使高沥青质含量的稠油井实现高效连续生产。     

Study of Asphaltene Precipitation Using Refractive Index Measurement

Abstract

The measurements of the refractive index of crude oils were utilized in this work to enhance the understanding of the behavior of asphaltenes in crude oil, specifically, their tendency to precipitate from crude oil. The onset of asphaltene precipitation was measured in eight crude oil samples, which were titrated with either heptane or pentane in order to induce precipitation of the asphaltenes. The refractive index of each sample was measured to find its relationship to asphaltene precipitation. The assumption that refractive index of a mixture is a linear combination of the refractive indexes of the individual components was verified. It was also found that mixtures of heptane or pentane and crude oil also followed this same behavior. However, as asphaltenes began to precipitate from the solution, the refractive index no longer followed this linear mixing rule. Careful analysis of the refractive index data for each of the crude oil samples revealed many interesting relationships between the refractive index data and the content of the different polar asphaltene fractions present. The refractive index of asphaltenes was predicted from the refractive index data of crude oils. The results suggest the possibility predicting the properties and characteristics of the asphaltenes contained in a crude oil simply by measuring the refractive index.