Identification and Evaluation of Low Resistivity Pay Zones by Well Logs and the Petrophysical Research in China

This paper presents an overview of petrophysical research and exploration achievements of low resistivity pay （LRP） zone by well logs in China. It includes geological characteristics and characteristics of well log response of the low resistivity pay zones discovered and evaluated in recent years, as well as the problems in recognizing and evaluating low resistivity pay zones by well logs. The research areas mainly include the Neogene formations in the Bohai Bay Basin, the Triassic formations in the northern Tarim Basin and the Cretaceous formations in the Junggar Basin, The petrophysical research concerning recognition and evaluation of the low resistivity pays, based on their genetic types, is introduced in this paper.

A new methodology for identification of potential pay zones from well logs: Intelligent system establishment and application in the Eastern Junggar Basin, China

In recent years, as the exploration practices extend into more complicated formations, conventional well log interpretation has often shown its inaccuracy and limitations in identifying hydrocarbons. The Permian Wutonggou Formation hosts typical clastic reservoirs in the Eastern Junggar Basin. The sophisticated lithology characteristics cause complex pore structures and fluid properties. These all finally cause low well testing agreement rate using conventional methods. Eleven years＇ recent statistics show that 12 out of 15 water layers have been incorrectly identified as being oil or oil/water layers by conventional well log interpretation. This paper proposes a methodology called intelligent prediction and identification system （IPIS）. Firstly, parameters reflecting lithological, petrophysical and electrical responses which are greatly related to reservoir fluids have been selected carefully. They are shale content （Vsh）, numbered rock type （RN）, porosity （φ）, permeability （K）, true resistivity （RT） and spontaneous-potential （SP）. Secondly, Vsh, φ and K are predicted from well logs through artificial neural networks （ANNs）. Finally, all the six parameters are input into a neuro-fuzzy inference machine （NFIM） to get fluids identification results. Eighteen new layers of 145.3 m effective thickness were examined by IPIS. There is full agreement with well testing results. This shows the system＇s accuracy and effectiveness.

Identification of low-resistivity-low-contrast pay zones in the feature space with a multi-layer perceptron based on conventional well log data

In the early exploration of many oilfields,low-resistivity-low-contrast(LRLC)pay zones are easily overlooked due to the resistivity similarity to the water zones.Existing identification methods are model-driven and cannot yield satisfactory results when the causes of LRLC pay zones are complicated.In this study,after analyzing a large number of core samples,main causes of LRLC pay zones in the study area are discerned,which include complex distribution of formation water salinity,high irreducible water saturation due to micropores,and high shale volume.Moreover,different oil testing layers may have different causes of LRLC pay zones.As a result,in addition to the well log data of oil testing layers,well log data of adjacent shale layers are also added to the original dataset as reference data.The densitybased spatial clustering algorithm with noise(DBSCAN)is used to cluster the original dataset into 49 clusters.A new dataset is ultimately projected into a feature space with 49 dimensions.The new dataset and oil testing results are respectively treated as input and output to train the multi-layer perceptron(MLP).A total of 3192 samples are used for stratified 8-fold cross-validation,and the accuracy of the MLP is found to be 85.53%.

The Distribution of Petroleum Resources and Characteristics of Main Petroliferous Basins along the Silk Road Economic Belt and the 21st-Century Maritime Silk Road

The Silk Road Economic Belt and the 21st-Century Maritime Silk Road Initiative, abbreviated as the Belt and Road Initiative, is a primary development strategy of China＇s future international cooperation. Especially, the energy resource cooperation, including oil and gas resources cooperation, is an important part of this initiative. The Belt and Road has undergone complicated geological evolution, and contains abundant mineral resources such as oil, gas, coal, uranium, iron, copper, gold and manganese ore resources. Among these, Africa holds 7.8% of the world＇s total proven oil reserves. The oil and gas resources in Africa are relatively concentrated, with an overall low exploration degree and small consumption demand. Nigeria and Libya contain the most abundant oil resources in Africa, accounting for 2.2% and 2.9% of the world＇s total reserves, respectively. Nigeria and Algeria hold the richest natural gas resources in Africa, occupying 2.8% and 2.4% of the world＇s total reserves, respectively. Africa＇s oil and gas resources are mainly concentrated in Egypt, Sultan and Western Sahara regions in the northern Africa, and the Gulf of Guinea, Niger River and Congo River area in the western Africa. The Russia--Central Asia area holds rich petroleum resources in Russia, Kazakhstan, Turkmenistan and Uzbekistan. The potential oil and gas areas include the West Siberia Basin, East Siberia Basin and sea continental shelf in Russia, the northern and central Caspian Basin in Kazakhstan, the right bank of the Amu-Darya Basin, the East Karakum uplift and the South Caspian Basin in Turkmenistan, and the Amu-Daria Basin, Fergana Basin, Afghan-Tajik Basin and North Ustyurt Basin in Uzbekistan. The Middle East oil and gas resources are mainly distributed in the Zagros foreland basin and Arabian continental margin basin, and the main oil-producing countries include Saudi Arabia, Iran and Iraq. The Asia Pacific region is a new oil and gas consumption center, with rapid growth of oil and gas demand. In 2012, this region consumed about 33.6% of the world＇s total oil consumption and 18.9% of the world＇s total natural gas consumption, which has been ranked the world＇s largest oil and gas consumption center. The oil and gas resources are concentrated in China, Indosinian, Malaysia, Australia and India. The abundant European proven crude oil reserves are in Norway, Britain and Denmark and also rich natural gas resources in Norway, Holland and Britain. Norway and Britain contain about 77.5% of European proven oil reserves, which accounts for only 0.9% of the world＇s proven reserves. The Europe includes main petroliferous basins of the Voring Basin, Anglo-Dutch Basin, Northwest German Basin, Northeast German-Polish Basin and Carpathian Basin. According to the analysis of source rocks, reservoir rocks, cap rocks and traps for the main petroliferous basins, the potential oil and gas prospecting targets in the Belt and Road are mainly the Zagros Basin and Arabic Platform in the Middle East, the East Barents Sea Basin and the East Siberia Basin in Russia-Central Asia, the Niger Delta Basin, East African rift system and the Australia Northwest Shelf. With the development of oil and gas theory and exploration technology, unconventional petroleum resources will play an increasingly important role in oil and gas industry.

Time Optimizing near the Pay Zone

Well control techniques are used in oil and gas drilling operations to control bottom hole pressure and avoid any fluid influx from formation to the well. These techniques are highly important near the pay zone in term of time. Controlling formation fluid pressure and thereby the formations behavior in a predictable fashion will help toward more optimized environmental friendly drilling operation. Time consumed to control the formation fluid pressure will range between few hours to many days. This paper discusses hydrostatic pressure distribution and changes near the pay zone for one oil blocks in Kurdistan, in the northern part of Iraq. Obtaining homogeneous increase in some drilling fluid properties will help the engineer to better interpret sampling of the lithological columns and reduce potential hole problems and operation time.

Reservoir Characterization and Pore Type Systems of Carbonate Low Resistivity Pay in Persian Gulf

The main focus of study is to characterize lower and upper cretaceous carbonate deposits with Low Resistivity Pay, in Persian Gulf. Four oil reservoirs in the Cretaceous including the Zubair, Buwaib, Shuaiba and Khatiyah Formations of Southern fields have been analyzed. Here is a look at that to determine main factors on decreasing resistivity in pay zone. In some intervals resistivity responses reach less than 6 to 1 ohm·m. Significant hydrocarbon accumulations are “hidden” in low resistivity Pay zone, (LRPZ). LRPZ reservoirs have been found in some formations in Persian Gulf. Causes of LRPZ reservoirs on the basis of experimental analysis include clay-coated grains, carbonate with interstitial dispersed clay. On the other side Smectite and Kaolinite of main clays types have high CEC and greater impact on lowering resistivity. Micritization and Pyritization of digenetic process have noticeable impact on LRPZ. It is mentioned that Lønøy method applied to address pore throat sizes which contain Inter crystalline porosity, Chalky Limestone, Mudstone micro porosity. Pore systems are classified at class 2 and 3 Lucia and pore size varies from 0.5 to 4 micron. NMR Core and Log results show different pore size distribution. NMR core and MRIL results explain that decreasing of resistivity in pay zone is related to texture and grain size variation not being existence of moved water. Irreducible water estimate for this reservoir was between 30% and 50%. T2 cut off estimates, for defining irreducible water saturation, 115 ms.

近端不良锚定区Stanford B型主动脉夹层介入治疗方式的研究进展

近端不良锚定区Stanford B型主动脉夹层介入治疗方式主要包括弓上分支动脉重建和非弓上分支动脉重建技术。弓上分支动脉重建技术相对于非弓上分支动脉重建技术有较低的不良事件发生率。弓上分支动脉重建介入治疗方式有多种,不同的介入治疗方式对胸主动脉腔内修复术疗效亦产生不同的影响。本文就不同介入治疗方式进行综述分析,为了更深入地分析和总结不同介入治疗方式对近端不良锚定区Stanford B型主动脉夹层的优、劣势和临床效果,以便为临床手术决策提供可行的参考依据。

陡坡区加筋土挡墙基底不良地质处理

以黑山南北高速公路项目中的一段隧道间陡坡区加筋土挡墙支挡路基为例,对挡墙基底不良地质情况及可能产生的路基侧向滑移风险进行描述,并就拟采用的四种处理方案进行比选,对其优劣势和经济性进行探讨,为后续类似项目可能出现的情况提供经验。

6306工作面覆岩导水裂缝带高度观测技术实践

本文深入探讨了矿井浅部第四系松散层下开采的水害防治问题,为提高开采上限、判断封闭不良的钻孔是否需要启封以及确保安全生产提供了科学且可靠的依据。通过实证研究观测,验证了井下施工仰上孔作为探测导水裂缝带的有效性。特别是双端堵水观测技术,在实践中展现出高精度、简便有效、重复性好以及显著的技术经济效益。这一技术的引入,不仅丰富了该地质条件下导水裂缝带的观测方法,更为安全生产提供了新的技术保障,标志着在矿井水害防治领域迈出了重要的一步。

薄差层水淹层测井解释技术研究

大庆油田进入二次加密调整以来 ,长垣萨葡高油层中的薄 (有效厚度≤ 0 5m)、差油层 (独立表外层 )成为加密调整的主要对象 ,该类油层非均质性严重 ,层数多 ,岩性、物性变化大、孔隙结构复杂 ,测井资料反映的水淹信息较弱 ,再加上高含水后期剩余油分布的复杂性 ,使得薄差层水淹层测井解释符合率较低。针对储层的地质特点及油田污水回注的开发现状 ,以油藏条件下水淹层导电机理研究为指导 ,提出了应用岩石物理相分析技术 ,突出水淹层测井响应信息的研究思路 ,并以萨中密闭取心资料为基础 ,形成了一套利用常规测井资料解释薄差层水淹层的方法及测井交互解释系统。经实际资料检验 ,解释符合率达到 75 0 %以上。

薄差储层油水渗流规律研究

应用岩心水动力实验数据归一化得到薄差层油水相对渗透率曲线。引入有效驱动系数,对驱油效率、含水上升规律、不同条件下采液采油指数的变化规律以及影响因素进行分析。研究表明:薄差层两相共渗区范围窄,驱油效率低,其相渗特征主要受表外储层影响;含水上升率在含水率为40%时达到最大,且分布不对称;较高的油水黏度比、较大的有效驱动系数有利于提高无因次采液指数、采油指数,因此薄差层开发应有效提高低含水期采出程度。

Fe－C合金贝氏体相变机制

贝氏体在奥氏体贫碳区马氏体式切变相变机制为：γ→γ＇（贫碳）＋γ１（富碳）→ｘ＇（与ｙ’同成分）＋γ１→ＢＦ＋γ１．整个相变过程受碳扩散控制．热力学分析表明，贝氏体切变形成具有热力学可能性，贝氏体相变具有阶段性特点．

西部贫困地区开发区发展模式探索——以甘肃省定西市开发区为例

以西部贫困地区开发区为研究对象,对西部地区贫困的特点进行了分析,认为现阶段西部地区摆脱贫困的有效措施是通过开发区的建设促进地方经济.在此基础上,对开发区建设的产业模式、空间模式和保障制度模式进行了研究.以甘肃省定西市开发区为例,研究了开发区的主导产业选择、产业协作、空间布局、保障措施等,认为西部贫困地区要摆脱贫困,应积极走农业产业化和发展新型工业带动经济发展的道路,通过建设开发区这种工业集聚发展的形式,快速有效地带动西部贫困地区的发展.

岩层阻水性能及自然导升高度研究

在沉积、成岩或者构造运动过程中,由于含水层内超压流体引起围岩爆裂导致流体在弱渗透层或者隔水层中导升,形成含水层的自然导升带。影响岩层阻水性能以及导升高度的因素有:构造、地应力、岩层渗透性和力学特性及其物理化学性质、水压力等。实验表明:初始水头压力越大,水头衰减速率就越大;水头压力损耗随着介质的渗透系数增大而减小。实际观测表明:泥岩、粉砂岩、中砂岩、灰岩的阻水性能由大到小,而导升高度则由小变大。通过实验和实际观测总结出流体3种导升机制:局部关键层整体破断裂缝、欠压实带中的壳破裂裂缝和水力压裂裂缝。

TBM通过断层破碎带的技术

主要论述了TBM (隧道掘进机 )快速通过断层破碎带的方法和步骤。介绍了断层破碎带通常存在的坍塌、涌水、软弱地层等不良地质情况可能对TBM施工造成的不利影响 ,并提出了相应的处理措施 。

薄差油层水淹解释研究

随着油田开发的不断深入 ,中国东部大多数油田已到了高含水开发期。高含水期 ,对厚油层挖潜实施三次采油技术要求细分层精细解释 ,二次加密调整的对象转向薄、差层。实质上 ,油田面临的是薄差油层水淹解释的问题。从理论上说 ,地层岩性、物性、含油性的变化 ,可以根据油层的电性特征识别和解释 ,但由于薄层的单层厚度小 ,泥质含量高 ,砂泥互层多等特征 ,使得测井曲线难以反映小层的特征。通过响应函数对测井曲线进行预处理来提高测井的纵向分辨率 。

萨南油水过渡带微生物解堵现场试验

介绍了萨南油水过渡带应用微生物解堵的现场试验情况。通过10口低产低效且高含水(含水60%~95%)试验井的现场应用,已累计增油1445 t,平均单井增液在50%以上,个别井高达到几倍,有效期大于6个月,最长13个月,平均单井增油145 t,有效率在70%。试验井微生物解堵后功图泵效提高10%~30%,节省了洗井作业费用,投入产出比大于1∶5。

薄差层水力压裂控缝高技术研究

对于低渗透薄差层的开发,水力压裂是非常有效的增产措施,而薄差层改造的最大技术难题是缝高的控制.本文归纳了影响缝高扩展的主要因素,针对这些因素,结合冀东油田的地质参数和施工参数设计了五水平七因素的正交方案,并利用FracproPT软件模拟了不同参数下裂缝的扩展情况,对影响缝高的各因素进行了敏感性分析和单因素分析.分析结果表明:影响缝高的各因素依次为隔/产层地应力差、施工规模、施工排量、压裂液粘度、隔/产层杨氏模量差、地层渗透率、断裂韧性差;隔/产层地应力差越大越有利于控制缝高,减小施工排量和压裂液粘度能减小缝内净压力而有利于控制缝高;油田实例表明,综合人工隔层、变排量和使用较小粘度压裂液能有效控制缝高.本研究对于薄差层的水力压裂优化设计和现场施工具有一定的指导作用.

北方农牧交错带仁用杏霜冻灾害分析及对策研究——以太行山北段贫困地区为例

以太行山北段贫困区为研究试点,运用实地调查法并结合研究区近20年有仁用杏栽培历史霜冻灾害信息以及4个仁用杏典型栽培区2010年气温资料,系统分析了杏树花芽膨大-初果期不同阶段面临的霜冻灾害隐患。研究结果表明:初花-盛花期为研究区仁用杏霜冻灾害多发时段,特定地区应根据当地小气候特征,因地制宜采取针对性防霜抗冻措施以减轻或避免霜冻灾害发生,实现贫困地区荒山绿化与果林经济效益双丰收。

宁夏移民扶贫开发的经验和效果

移民扶贫开发是中国农村扶贫的一种重要方式。回顾了宁夏移民扶贫开发三个阶段,即吊庄移民(1983-2000)、易地生态移民(2001-2007)和现阶段中部干旱带县内生态移民(2007-2011年)的情况,探讨了宁夏移民扶贫开发的经验主要是政府主导型移民;省内近距离移民;在确保资金到位的前提下坚持了因地制宜,效益为重的原则和多元开发模式。最后论述了当前移民工程所面临的挑战。