Pore structure differences of the extra-low permeability sandstone reservoirs and the causes of low resistivity oil layers: A case study of Block Yanwumao in the middle of Ordos Basin, NW China

The influence of pore structure difference on rock electrical characteristics of reservoir and oil reservoir was analyzed taking Triassic Chang 6 reservoir in Block Yanwumao in the middle of Ordos Basin as an example. The relationship between the pore structure difference and the low resistivity oil layer was revealed and demonstrated through core observation, lab experiments, geological research, well log interpretation and trial production etc. The results show that there were two kinds of oil layers in Chang 6 oil layer set, normal oil layer and low resistivity oil layer in the region, corresponding to two types of pore structures, pore type mono-medium and micro-fracture-pore type double-medium; the development of micro-fracture changed greatly the micro-pore structure of the reservoir, and the pore structure difference had an important influence on the rock electrical characteristics of the extra-low permeability sandstone reservoir and oil reservoir; the normal oil layers had obvious characteristics of pore-type mono-medium, and were concentrated in Chang 61, Chang 6232 and Chang 62; the low resistivity oil layers had obvious characteristics of micro-fracture-pore type double-medium, which were mainly distributed in Chang 612 and Chang 63. The mud filtrate penetrated deep into the oil layers along the micro-cracks, leading to sharp reduction of resistivity, and thus low resistivity of the oil layer; the low resistivity oil layers had better storage capacity and higher productivity than the normal oil layers.

Micro-geological causes and macro-geological controlling factors of low-resistivity oil layers in the Puao Oilfield

Low-resistivity oil layers are often missed in logging interpretation because of their resistivity close to or below the resistivity of nearby water layers. Typical low-resistivity oil layers have been found in the past few years in the Putaohua reservoir of the Puao Oilfield in the south of the Daqing placanticline by detailed exploration. Based on a study of micro-geological causes of low-resistivity oil layers, the macro-geological controlling factors were analyzed through comprehensive research of regional depositional background, geological structure, and oil-water relations combined with core, water testing, well logging, and scanning electron microscopy data. The results showed that the formation and distribution of Putaohua low-resistivity oil layers in the Puao Oilfield were controlled by depositional environment, sedimentary facies, diagenesis, motive power of hydrocarbon accumulation, and acidity and alkalinity of reservoir liquid. The low-resistivity oil layers caused by high bound-water saturation were controlled by deposition and diagenesis, those caused by high free-water saturation were controlled by structural amplitude and motive power of hydrocarbon accumulation. Those caused by formation water with high salinity were controlled by the ancient saline water depositional environment and faulted structure and those caused by additional conductivity of shale were controlled by paleoclimate and acidity and alkalinity of reservoir liquid. Consideration of both micro-geological causes and macro-geological controlling factors is important in identifying low-resistivity oil layers.

Influence of shallow low resistivity thin layer on SATEM response at different receiving heights in near and far regions

In recent years,the semi-airborne transient electromagnetic method(SATEM)has been rapidly developed in China.Based on the theoretical development of the long grounding wire source transient electromagnetic method,the unmanned aerial vehicle is equipped with the receiving coil to collect the electromagnetic response data at high altitude,making the TEM no longer affected by the terrain and greatly improving the actual working efficiency.However,its flight altitude has not been concerned for a long time.It is generally believed that the change of flight altitude only affects the amplitude of the received response.However,under special circumstances,the electromagnetic response data received at different flight altitudes in the near and far regions may lose the characteristic information of the target geological body.This paper simulates the low resistance thin layer model and analyzes the electromagnetic responses of different receiving heights under different transceiver distances.The results show that in the near area,when the flight altitude is higher than 30 meters or more,the received electromagnetic response will lose the information of the shallow lowresistance thin layer,while in the far area,the change of flight altitude has no obvious influence on the characteristic electromagnetic response information of the received geological body.

Layered injection technology for chemical flooding of Class-Ⅲ oil reservoirs in the Daqing Oil Fields complex,Songliao Basin,Northeast China

The Class-Ⅲ oil reservoirs of Lasaxing oilfield in the Daqing Oil Fields complex have geological oil reserves of 1.86 billion tonnes,an oil recovery of 39%,with remaining reserves accounting for more than 45%of the total geological reserves of the oilfield.Therefore,they have considerable potential for future oil production.The current layered injection technologies fail to achieve effective control over the low single-layer injection rates since they can only produce low throttle differential pressure under low injection rates(5-20 m^(3)/d).In this study,a symmetrically-structured double-offset-hole injection allocator and a novel throttling component were developed.Their spatial layout was constructed and mechanical parameters were optimized using finite element analysis,which allows for expanding the flow rate range at low injection rates.According to experimental results,the throttle differential pressure increased from 0.2 MPa to 0.8 MPa at an injection rate of 5 m^(3)/d,and the range of the single-layer flow rates expanded from 20-70 m^(3)/d to 5-70 m3/d.The field test results show that the effective production of oil layers with medium and low permeability was achieved and that the ratio of producing oil layer thickness to the total reservoir thickness increased by 9.7%on average.Therefore,this study provides valuable technical support for the effective chemical-flooding-based development of Class-Ⅲ oil reservoirs.

A novel profile modification HPF-Co gel satisfied with fractured low permeability reservoirs in high temperature and high salinity

Conformance control and water plugging are a widely used EOR method in mature oilfields.However,majority of conformance control and water plugging agents are unavoidable dehydrated situation in high-temperature and high-salinity low permeability reservoirs.Consequently,a novel conformance control system HPF-Co gel,based on high-temperature stabilizer(CoCl_(2)·H_(2)O,CCH)is developed.The HPF-Co bulk gel has better performances with high temperature(120℃)and high salinity(1×10^(5)mg/L).According to Sydansk coding system,the gel strength of HPF-Co with CCH is increased to code G.The dehydration rate of HPF-Co gel is 32.0%after aging for 150 d at 120℃,showing excellent thermal stability.The rheological properties of HPF gel and HPF-Co gel are also studied.The results show that the storage modulus(G′)of HPF-Co gel is always greater than that of HPF gel.The effect of CCH on the microstructure of the gel is studied.The results show that the HPF-Co gel with CCH has a denser gel network,and the diameter of the three-dimensional network skeleton is 1.5-3.5μm.After 90 d of aging,HPF-Co gel still has a good three-dimensional structure.Infrared spectroscopy results show that CCH forms coordination bonds with N and O atoms in the gel amide group,which can suppress the vibration of cross-linked sites and improve the stability at high temperature.Fractured core plugging test determines the optimized polymer gel injection strategy and injection velocity with HPF-Co bulk gel system,plugging rate exceeding 98%.Moreover,the results of subsequent waterflooding recovery can be improved by 17%.

Ultra-low specific on-resistance high-voltage vertical double diffusion metal–oxide–semiconductor field-effect transistor with continuous electron accumulation layer

A new ultra-low specific on-resistance （Ron,sp） vertical double diffusion metal-oxide-semiconductor field-effect tran- sistor （VDMOS） with continuous electron accumulation （CEA） layer, denoted as CEA-VDMOS, is proposed and its new current transport mechanism is investigated. It features a trench gate directly extended to the drain, which includes two PN junctions. In on-state, the electron accumulation layers are formed along the sides of the extended gate and introduce two continuous low-resistance current paths from the source to the drain in a cell pitch. This mechanism not only dramatically reduces the Ron,sp but also makes the Ron,sp almost independent of the n-pillar doping concentration （Am）. In off-state, the depletion between the n-pillar and p-pillar within the extended trench gate increases the Nn, and further reduces the Ron,sp. Especially, the two PNjunctions within the trench gate support a high gate--drain voltage in the off-state and on-state, re- spectively. However, the extended gate increases the gate capacitance and thus weakens the dynamic performance to some extent. Therefore, the CEA-VDMOS is more suitable for low and medium frequencies application. Simulation indicates that the CEA-VDMOS reduces the Ron,sp by 80% compared with the conventional super-junction VDMOS （CSJ-VDMOS） at the same high breakdown voltage （BV）.

奥连特盆地隐蔽油藏高效滚动勘探开发方法技术及应用——以厄瓜多尔14和17区块为例

厄瓜多尔14和17区块位于奥连特盆地前渊带,主要含油层系为Napo组的M1,U和T段。现已开发油田进入高含水阶段,资源接替面临挑战。通过基于趋势面驱动的叠后地震数据连片一致性处理、时-频衰减高精度合成记录标定和解释及各向异性变速成图,精细刻画了低幅度构造,发现了一批低幅度构造油藏。采用分频迭代去噪拾取薄层弱反射系数,以其重构的叠后宽频有效信号为约束,采用相控波形非线性反演,定量预测了埋深3 000 m的2~5 m厚潮汐水道砂岩,发现了多个M1超薄层岩性油藏。依据区域水动力条件、低幅度构造油藏油-水界面趋势及油藏能量特征,发现了LU水动力油藏并滚动扩边。通过观察大量岩心薄片,发现海绿石在石英砂岩储层中呈胶结物和颗粒两种赋存状态,建立了海绿石双组构测井解释体积模型,评价并识别了UT低电阻率油藏。基于热带雨林地表和隐蔽油藏特点,按照“整体部署、分批实施、跟踪评价、及时调整”的策略,实现滚动勘探、评价和快速建产,探井和评价井成功率大于90%。

风化店地区低阻油层成因分析及识别

针对风化店地区孔店组低阻油层识别困难、测井解释难度大的特点,充分利用测井、录井等资料研究分析低阻油层形成原因。研究认为该区低阻油层受黏土矿物含量、地层水矿化度、薄互层三个方面影响。在系统分析储层四性关系的基础上,分区块、分层位建立了储层参数模型和高精度、适用性强的油、水解释图版标准,准确识别低阻油层,及时应用于现场生产中,取得了明显的效果,为进一步开展老油田低阻油层识别、挖潜上产提供了借鉴和技术保障。

基于灰色关联度分析-极限学习机的低阻油层及水淹层测井识别——以渤海P区块馆陶组为例

历经近20的开发,渤海P区块进入高含水期,馆陶组发育的大量低阻油层与水淹层在测井曲线形态上差异不明显。为了精确进行水淹层识别以及水淹层等级划分,采用了机器学习算法。首先采用灰色关联度分析,筛选低阻油层和水淹层识别的敏感参数曲线;其次构建了极限学习机水淹层识别模型,对模型进行训练,获取最优参数。将其应用于实际资料处理,结果表明,基于灰色关联度分析极限学习机的低阻油层及水淹层测井识别方法对低阻油层与水淹层的预测精度较高,符合率达89.3%,远远优于未经过灰色关联度分析筛选的预测结果,具有实际应用价值。

高温中低渗油藏智能纳米黑卡驱提高采收率技术

当前化学驱储量接替严重不足,亟需攻关突破高温中低渗油藏提高采收率技术。智能纳米黑卡驱油技术是当下极具前瞻性的纳米驱油技术,可大幅度提高采收率。针对河南油田高温中低渗油藏,开展高温条件下纳米黑卡静态性能评价,并通过高温岩心驱替实验评价不同渗透率条件下智能纳米黑卡驱油效果。结果表明,智能纳米黑卡具有优异的耐高温性能,分散稳定性好,能够降低油水界面张力至10^(-1)mN/m,并具有改变润湿性和快速乳化与破乳性能。同时,纳米黑卡具有高效的洗油能力,在95℃下注入0.3 PV的质量分数为0.005%的智能纳米黑卡溶液,在目标油田不同渗透率(50×10^(-3)~450×10^(-3)μm^(2))条件下可提高采收率15.8百分点~20.0百分点。因此,智能纳米黑卡驱油技术适用于河南油田高温中低渗油藏提高采收率。

生物油/预处理废旧PE复合改性沥青研究

为了解决废旧塑料改性沥青储存稳定性和低温抗裂性差等问题,采用双螺杆挤出机对废旧聚乙烯(PE)进行预处理,并将其与生物油复合制得生物油/预处理废旧PE复合改性沥青.采用离析试验、流变性能试验、荧光显微镜试验和傅里叶变换红外光谱试验分析了改性沥青的储存稳定性、低温抗裂性和高温稳定性.结果表明:经预处理后的PE密度与沥青密度相近,极性基团和C=C结构更多,化学活性增强,大大提高了废旧PE改性沥青的储存稳定性;生物油/预处理废旧PE复合改性沥青形成了连续的网状结构,进一步提高了废旧PE改性沥青的储存稳定性,并显著提升了其低温抗裂性,但降低了其高温稳定性.

地面瞬变电磁法对低阻薄层的分辨能力

瞬变电磁法现阶段的资料处理解释仍以一维反演为主,因此分析瞬变电磁法对薄层的分辨能力对于更好地发挥瞬变电磁法优势仍具有重要意义。采用基于Occam算法的一维反演,以100 m深度内10 m层厚的低阻薄层为例,开展了地面回线源瞬变电磁法对低阻薄层分辨能力的定性和定量研究。数值结果表明:低阻薄层电阻率与背景电阻率差异越大,薄层反演电阻率和层厚越接近于真实值;反演电阻率极小值位置始终对应于薄层位置。低阻薄层电阻率与背景电阻率比值为1∶5,1∶10,1∶20,背景电阻率小于100Ω·m时,瞬变电磁法能够良好探测10 m薄层的最大埋深依次为40,50,80 m;背景电阻率为200Ω·m时,上述3个最大埋深依次为30,30,60 m。上述研究成果有助于优化瞬变电磁法野外工作参数设计和提高资料处理解释精度。

增塑体系对氢化丁腈橡胶性能的影响

研究增塑剂种类及用量对氢化丁腈橡胶(HNBR)性能的影响。结果表明:采用增塑剂TP-95的HNBR胶料的t_(10)和t_(90)较短,相应硫化胶具有较好的耐低温性能;采用增塑剂DOS的HNBR硫化胶具有较大的硬度和拉伸强度以及良好的耐油性能;随着增塑剂用量的增大,HNBR胶料的门尼粘度明显下降,硫化胶的耐低温性能改善;当采用20份增塑剂DOS时,HNBR硫化胶具有较好的物理性能和耐油性能,同时具有较好的耐低温性能。

渤海A油田馆陶组低阻油层成因机理研究及流体性质识别新方法

低阻油层作为一种非常规、隐蔽性强的特殊油层,勘探潜力巨大。研究区低阻油层的形成受多重因素的影响,测井响应特征在油水层的对比度较低,造成测井解释困难。为此,首先从宏观和微观两个方面深入分析低阻油层的成因机理;其次,将测井、气测录井以及生产开发资料相结合,针对研究区气测烃组分数据的特点,改进了含油气丰度计算方法用以定量识别低阻油层。结果表明:弱水动力环境和压实作用是低阻油层的宏观成因,孔隙结构复杂导致的高束缚水饱和度是普遍微观成因,天然淡水水淹成藏模式导致的油水层矿化度差异是主控成因。改进的含油气丰度能够有效定量的识别研究区低阻油层,解释符合率达到84.7%,可以为渤海A油田低阻油层的挖潜工作提供定量依据。

胍胶压裂液有机硼交联剂JSA-1的合成与性能评价

以硼酸、正丁醇、乙二醇、二乙烯三胺为反应原料,采用一锅法合成了有机硼交联剂(JSA-1)。考察了胍胶质量分数(即含量,以胍胶占胍胶基液总质量计)、JSA-1用量(即添加量,以胍胶基液质量为基准,下同)、pH对JSA-1交联性能的影响。结果表明,胍胶质量分数越大(0.09%~0.4%),胍胶压裂液的交联状态越好、交联时间越短、表观黏度越高、耐温能力越强;JSA-1用量越大(0.04%~0.4%),胍胶压裂液的交联状态越好、交联时间越短、耐温能力越强;pH(pH=4~14)越高,胍胶压裂液的交联时间越长、耐温能力越强。JSA-1对pH和胍胶质量分数的适用范围较广,在低温配方中,可以使低质量分数的胍胶实现有效交联,胍胶质量分数为0.13%的胍胶基液与JSA-1交联后,在常温、100 s^(–1)剪切下表观黏度可达到50 mPa·s;在高温配方中,胍胶质量分数为0.4%的胍胶基液与JSA-1交联后制备的压裂液具备较好的耐温耐剪切能力,在120℃、100 s^(–1)剪切条件下表观黏度可以稳定保持在300 mPa·s左右。

基于门控循环单元网络的低阻油层测井流体识别方法

研究区块低阻油层发育广泛,油层和水层的电阻率相差不大,导致测井流体识别较为困难。为了有效识别低阻油层,采用少数类过采样技术(synthetic minority oversampling technique,Smote)对油水同层,油层等少数类样本进行过采样使数据集均衡;并利用门控循环单元(gated recurrent unit,GRU)网络模型进行低阻油层的流体识别。通过相关性分析确定自然伽马(GR)、深侧向电阻率(RD)、密度(DEN)等8条测井曲线数据作为输入训练模型,应用于中实际资料中,并将GRU与传统RNN和其他3种机器学习算法对比。结果表明:序列数据模型的流体识别效果比传统机器学习模型好,且基于Smote-GRU的流体识别模型的符合率达到89.5%,相对传统循环神经网络(recurrent neural network,RNN)的81.1%,取得了较好的应用效果。通过对照试验还证实了Smote算法提高了分类器对少数类样本的识别率。所提出的方法可为样本不均衡的低阻油层的流体识别提供参考。

稀土Ce对低碳微合金钢耐腐蚀性能的影响

为了提高低碳微合金钢在海洋环境中的耐腐蚀性能,采用金相显微镜、SEM、EBSD、电化学分析等测试手段研究了不同稀土Ce含量的试验钢在3.5%NaCl溶液模拟的海洋环境中的腐蚀行为。结果表明:试验钢的显微组织主要由铁素体和珠光体组成,稀土Ce可以细化晶粒,减小夹杂物的尺寸,将试验钢中Al_(2)O_(3)、MnS、Al_(2)O_(3)+MnS夹杂物改性为MnS+CeAlO_(3)、Ce_(2)O_(3)夹杂物,并且改性后的夹杂物应力明显降低,减小了微孔洞、裂纹萌生的概率。另外,稀土Ce的加入可以降低试验钢的腐蚀电流密度,提高腐蚀电压,使得腐蚀产物中γ-FeOOH的含量减少,同时α-FeOOH和Fe_(3)O_(4)含量增多,可降低反应活性,提高锈层对基体的保护作用。因此,相对于未添加稀土Ce的低碳微合金钢,添加稀土Ce的低碳微合金钢表现出更好的耐海水腐蚀性能。

中拐凸起南斜坡八道湾组油层低阻成因及识别

准噶尔盆地中拐凸起南斜坡下侏罗统八道湾组低阻油层与一般低阻油层对比,储集层具有形成时期早、埋藏深度大、岩石粒度较大、泥质含量低等特点,低阻成因具有较强特殊性。在对国内外典型低阻油层成因机理综合研究的基础上,利用该区钻井、录井、测井、试井、岩心化验分析等资料,从构造、沉积、成岩作用、储集层特征、成藏条件等多角度,开展八道湾组油藏低阻主控因素研究。该区油藏低阻的形成受宏观因素和微观因素共同控制,低构造幅度、弱水动力沉积等宏观背景下,低油水分异程度、高地层水矿化度及低凝灰岩岩屑含量,是油藏低阻的主控因素;束缚水饱和度偏低,是油藏低阻的次要控制因素。在此基础上,建立地层电阻率与油气指示系数关系图版,与该区试油和试采资料对比,符合率92.9%,为中拐凸起南斜坡八道湾组低阻油层的识别提供了依据。

共混比对乙丁橡胶/丁腈橡胶共混胶性能的影响

采用共混法制备了乙丁橡胶(EBT)/丁腈橡胶(NBR)共混胶,研究了不同共混比对其硫化特性、物理机械性能、压缩永久变形、耐老化性能、耐低温性能、玻璃化转变温度及耐油性能的影响。结果表明,随着EBT用量的增加,共混胶的拉伸强度、撕裂强度和扯断伸长率均逐渐降低,而硬度和定伸应力则逐渐升高,压缩永久变形逐渐变大;随着EBT用量的增加,共混胶的耐热空气老化性能呈现先降低后升高的趋势,耐臭氧老化性能得到改善,耐低温性能提升,但耐油性能下降;当m(EBT)/m(NBR)为30/70时,共混胶综合力学性能和耐油性能稍有下降,但耐低温性能和耐臭氧老化性能明显提升。

水分对混合动力汽车发动机油性能的影响

利用机械搅拌机将蒸馏水均匀分散在发动机油中,形成“油包水”结构的稳定乳化液,利用石油产品低温泵送黏度测定法、铜片腐蚀测定法、润滑油氧化诱导期测定法、倾点测定法、四球法分别评价水分对混合动力汽车发动机油理化性能的影响。试验结果表明:水分对油品的低温泵送黏度、氧化诱导期、最大无卡咬负荷、烧结负荷及磨斑直径等性能有影响,随着水含量的增加,其油品的低温流动性、抗氧化性、承载能力及抗磨损性能变差;对油品的倾点、腐蚀性能基本无影响。(图0表5参考文献5)