The McMurray Formation is one of the most significant bitumen deposits in Canadian oil sands. Bitumen-bearing sand intervals deposited and reworked in fluvial, tidal or estuarine environments result in heterogeneous sediment distributions comprising clean sands and low-permeability muddy laminae or mud drapes. These interlayers increase the difficulty in estimating reservoir permeability, which is a critical geological parameter to predict the performance of in situ thermal processes of the oil sands projects. In this paper, we describe a bedding-scale geomodelling and simulation workflow using core images, core-plug and Vshale logs to estimate the effective permeability (Kh, Kv) in the Upper McMurray Formation. Details of five steps in this workflow are presented. To show the general applicability of this workflow, three pay-zone facies from tidal-channel infilled deposits of the Mackay River Project, CNPC, were selected to demonstrate this sedimentary process mimicking bedding-scale geomodelling strategy. The results of effective permeability estimation have the potential to improve history matching in flow simulations and performance forecasting.

Carboniferous carbonate reservoirs at the eastern edge of the Pre-Caspian Basin have undergone complex sedimentation, diagenesis and tectonism processes, and developed various reservoir space types of pores, cavities and fractures with complicated combination patterns which create intricate pore-throats structure. The complex pore-throat structure leads to the complex porosity-permeability relationship, bringing great challenges for classification and evaluation of reservoirs and efficient development. Based on the comprehensive analysis on cores, thin sections, SEM, mercury intrusion, routine core analysis and various tests, this paper systematically investigated the features and main controlling factors of pore-throats structure and its impact on the porosity-permeability relationship of the four reservoir types which were pore-cavity-fracture, pore-cavity, pore-fracture and pore, and three progresses are made. (1) A set of classification and descriptive approach for pore-throat structure of Carboniferous carbonate reservoirs applied to the eastern edge of the Pre-Caspian Basin was established. Four types of pore-throat structures were developed which were wide multimodal mode, wide bimodal mode, centralized unimodal mode and asymmetry bimodal mode, respectively. The discriminant index of pore-throat structure was proposed, realizing the quantitative characterization of pore-throat structure types. (2) The microscopic heterogeneity of pore reservoir was the strongest and four types of pore-throat structures were all developed. The pore-fracture and pore-cavity-fracture reservoirs took the second place, and the microscopic heterogeneity of pore-cavity reservoir was the weakest. It was revealed that the main controlling factor of pore-throat structure was the combination patterns of reservoir space types formed by sedimentation, diagenesis and tectonism. (3) It was revealed that the development of various pore-throat structure types was the important factor affecting poroperm relationship of reservoirs. The calculation accuracy of permeability of reservoirs can be improved remarkably by subdividing the pore-throat structure types. This study deepens the understanding of pore-throat structure of complicated carbonate reservoirs, and is conducive to classification and evaluation, establishment of precise porosity-permeability relationship and highly efficient development of carbonate reservoirs.

This study reviews the development history of PetroChina’s overseas oil and gas field development technologies, summarizes the characteristic technologies developed, and puts forward the development goals and technological development directions of overseas business to overcome the challenges met in overseas oil and gas production. In the course of PetroChina’s overseas oil and gas field production practice of more than 20 years, a series of characteristic technologies suitable for overseas oil and gas fields have been created by combining the domestic mature oil and gas field production technologies with the features of overseas oil and gas reservoirs, represented by the technology for high-speed development and stabilizing oil production and controlling water rise for overseas sandstone oilfields, high efficiency development technology for large carbonate oil and gas reservoirs and foamy oil depletion development technology in use of horizontal wells for extra-heavy oil reservoirs. Based on in-depth analysis of the challenges faced by overseas oil and gas development and technological requirements, combined with the development trends of oil and gas development technologies in China and abroad, overseas oil and gas development technologies in the future are put forward, including artificial intelligence reservoir prediction and 3 D geological modeling, secondary development and enhanced oil recovery（EOR） of overseas sandstone oilfields after high speed development, water and gas injection to improve oil recovery in overseas carbonate oil and gas reservoirs, economic and effective development of overseas unconventional oil and gas reservoirs, efficient development of marine deep-water oil and gas reservoirs. The following goals are expected to be achieved: keep the enhanced oil recovery（EOR） technology for high water-cut sandstone oilfield at international advanced level, and make the development technology for carbonate oil and gas reservoirs reach the international advanced level, and the development technologies for unconventional and marine deep-water oil and gas reservoirs catch up the level of international leading oil companies quickly.

A deep learning method for predicting oil field production at ultra-high water cut stage from the existing oil field production data was presented, and the experimental verification and application effect analysis were carried out. Since the traditional Fully Connected Neural Network (FCNN) is incapable of preserving the correlation of time series data, the Long Short-Term Memory (LSTM) network, which is a kind of Recurrent Neural Network (RNN), was utilized to establish a model for oil field production prediction. By this model, oil field production can be predicted from the relationship between oil production index and its influencing factors and the trend and correlation of oil production over time. Production data of a medium and high permeability sandstone oilfield in China developed by water flooding was used to predict its production at ultra-high water cut stage, and the results were compared with the results from the traditional FCNN and water drive characteristic curves. The LSTM based on deep learning has higher precision, and gives more accurate production prediction for complex time series in oil field production. The LSTM model was used to predict the monthly oil production of another two oil fields. The prediction results are good, which verifies the versatility of the method.

Tight oil production has gradually grown into the main driving force of crude oil production growth in the U.S. as well as an important contributor to the global crude oil supply. Agencies tend to forecast U.S. tight oil production tendency based on different resource and technology conditions. However, tight oil production is not only affected by the technical factors but also economical ones such as the well costs and the oil prices. To solve this problem, the exploration and development statuses of important tight oil reservoirs in the U.S. are investigated from both the technical and economic aspects. With the investigation results, the tight oil production tendencies of six plays including Bakken, Eagle Ford, Bone Spring, Wolfcamp and Niobrara are been achieved according to the oil & gas production composition method. And the forecasting result shows that the tight oil production in the U.S. will reach the peak level at about 8.3 million barrels per day in the year 2025. Permian basin is the core area of tight oil production in the United States, especially the Wolfcamp-Midland sub-play. The Wolfcamp sub-play is far ahead of other tight oil production areas in terms of reserve size, sweet spot size and production level, and will be the biggest driver of tight oil production in the United States in the future.

近10年来,全球油气勘探投资总体呈快速增长态势,但受2014年以来低油价影响,最大跌幅曾高达60％,目前已呈现触底回升态势,预计未来几年延续低位震荡态势.全球油气勘探活动呈“两减、一增、一波动”特点,重磁力勘探工作量总体维持在较低水平,二维地震采集呈周期性震荡减少,三维地震采集稳步增加,风险探井和勘探评价井数量逐年减少,风险探井占比基本稳定.深水、超深水成为重要的储量增长点,天然气领域勘探增长迅猛,非常规油气成为全球油气储量增长的重要组成部分.未来全球油气勘探的重点仍将集中南大西洋盐下碳酸盐岩、中大西洋两岸浊积砂体和碳酸盐岩等13个重点领域.建议中国石油企业根据自身技术实力,积极参与上述领域的油气合作,把深水和超深水、天然气两大领域作为未来资产配置的重点.

The re-injection of associated sour gas, with high H 2 S and CO 2 content, into the reservoir is proposed to be an effective development method due to its low investment cost and high oil recovery. The aim of this work is to present the phase behavior and miscible mechanism of crude oil displaced by associated sour gas. Based on the equation of state and the phase equilibrium theory, the phase behavior of crude oil mixed with various gases (associated sour gas, H 2 S, CO 2 and CH 4 ) have been analyzed. Then, the miscibility of associated sour gas was determined by calculating its Minimum Miscible Pressure (MMP) and the effect of sour component fraction on miscibility was evaluated. Moreover, a series of numerical simulations modeling 1D slim-tube were conducted using a compositional simulator to study the miscible mechanism in the displacement of crude oil with associated sour gas. The results show that the injection of H 2 S can reduce the bubble point pressure of crude oil and therefore is beneficial to prevent the crude oil degassing; nevertheless, the injection of CO 2 has little effect on it. The miscible ability of associated sour gas decreases as its sour component fraction decreases. It is observed that the crude oil displaced by associated sour gas and sweet gas both show a combined condensing/vaporizing mechanism, with miscible zone in the middle of transition zone. However, the vaporizing-gas drive mechanism is slightly stronger than the condensing-gas drive mechanism during the displacement by associated sour gas while is significantly stronger during the displacement by sweet gas.

Through a comprehensive review of PetroChina overseas oil and gas exploration of more than 20 years, we systematically summarize the development history, development status and application results of the overseas oil and gas exploration theory and technology. Overseas oil and gas exploration has experienced four stages, exploratory exploration, progressive exploration, risk exploration and efficient exploration. The overseas exploration theory and technology have also gone through the initially direct borrow of domestic mature technology to the integrated application, and then to the research innovation based on overseas features. A series of overseas oil and gas exploration theories and technologies represented by theories and technologies for passive rift basins, salt basins and foreland basin slopes, and global oil and gas geology and resource evaluation have been established. On the basis of deep analysis of the future overseas exploration development demand for the technology, and combined with the domestic and overseas future development trend of theory and technology, this paper systematically discusses the overseas exploration difficulties, technical requirements and the main development directions and aims of exploration theory and technology in the future: (1) Develop conventional onshore oil and gas exploration techniques continuously for the overseas exploration and keep them at an internationally advanced level. (2) Develop the global oil and gas resources and assets integrated optimization evaluation technology and its information system construction project innovatively to reach the international leading level. (3) Develop the deep water exploration technology integratively and narrow the gap with the world's advanced level.

To describe the distribution of sandstone reservoirs between wells finely, this paper takes the sandstone reservoir of Layer NmII-4 in Qinhuangdao 32–6 Oilfield for example, and uses the seismic forward simulation and well loggings to study the channel sandstone reservoir. Under the guidance of the modern rivers and outcrops sandstone distribution pattern, the predicting limitations of the seismic forward simulation about channel sandstone boundaries such as mudstone interlayer between channel sandstone and elevation distance between adjacent channel sandstone are clear. The research shows that the mudstone interlayer can be described by seismic forward simulation seismic when the mudstone interlayer is thicker than 2 m and the channel sandstone is thicker than 10 m because of the appearance of the seismic peak when the main frequency of seismic data is nearly 60 Hz. And the elevation distance between adjacent channel sandstone can be described by the seismic forward simulation when elevation distance is longer than 6 m and the channel sandstone is thicker than 10 m because of the appearance of the seismic peak. And the seismic waveform features of single channel sandstone boundaries such as elevation distance between channels, overbank sandstone and abandoned channels. Under the study mentioned above, the single channel boundaries are described in Layer NmII-4 of Qinhuangdao 32–6 Oilfield, and the predicting boundaries are confirmed by the chemical tracers. The results show that the channel sandstone reservoir architecture characterization can be improved by the seismic forward simulation.

Based on the optimal control theory and taking the production law of reservoirs with strong natural aquifer as the basic constraint, a mathematical model of liquid production for such reservoirs in the later stage of development is established. The model is solved by improved simultaneous perturbation stochastic approximation algorithm（SPSA）, and an automatic optimization software for liquid production is developed. This model avoids the disadvantage of traditional optimization methods that only focus on the maximum value of mathematics but ignore the production law of oilfield. It has the advantages of high efficiency of calculation, short period and automatic optimization. It can satisfy the automatic optimization of liquid production in later stage of oilfield development. The software was applied in the oilfield development of D oilfield, Ecuador in South America, and realized the automatic optimization of liquid production in the later stage of oilfield development.

油砂储层内大量发育的毫米至厘米级泥质纹层会显著降低热采开发效益.为明确泥质纹层的发育特征,以加拿大麦凯河油砂区块下白垩统McMurray组上段为研究对象,基于泥质纹层定性研究成果,针对不同类别泥质纹层的岩心照片,利用Matlab软件开展了数学形态学图像处理,在一定误差范围内统计了6类泥质纹层的泥质含量、纹层厚度和发育频数等定量表征参数,有效地将泥质纹层定性研究成果定量化.结果表明:6种泥质纹层的单条纹层厚度变化范围为0.2～6 cm,发育频数为32～95条/m,泥质含量为9％～51％.在形态学处理过程中,图像二值化的分割阈值是影响参数精度的主要因素;对图像进行先腐蚀后膨胀的形态学运算能够在保留关键信息的前提下,去除无效噪点.提出了将数学形态学图像处理技术应用到岩心照片的定量研究中,为充分挖掘岩心照片信息和提高资料处理效率提供了技术支撑.

Based on about 20 years of accumulated experience and knowledge of oil and gas field development in overseas countries and regions for China’s oil companies, the development features, ideas, models and plan designing strategies of overseas oil and gas fields were comprehensively summarized. Overseas oil and gas field development has ten major features, such as non-identity project resource, diversity of contract type, complexity of cooperation model, and so on. The overseas oil and gas field development aims at the maximization of production and benefit during the limited contract period, so the overseas oil and gas field development models are established as giving priority to production by natural energy, building large-scale production capacity, putting into production as soon as possible, realizing high oil production recovery rate, and achieving rapid payback period of investment. According to the overseas contract mode, a set of strategies for overseas oil and gas field development plans were made. For tax systems contracts, the strategy is to adopt the mode of "first fat and then thinner, easier in the first and then harder", that is, early investment pace, production increase rate, development workload and production were decided by the change of tax stipulated in the contract. For production share contracts, the strategy is to give priority to high production with a few wells at a high production recovery rate to increase the cost-oil and shorten the period of payback. For technical service contracts, the strategy is that the optimal production target and workload of the project were determined by the return on investment, so as to ensure that the peak production and stable production periods meet the contract requirements.

Taking the high-sinuosity distributary-channel reservoir in the close well-spacing block of Xingbei Oilfield as an example,based on the depositional model of the reservoir architecture theory,with the help of analytical hierarchy process,the reservoir architectures were analyzed in detail in the following four aspects:channel complex,individual channel,point bar and lateral accretion body within the point bar,on the basis of the mutual verification of “the static remained oil analysis” interpreted by the close coring well and watered well logging and " the dynamic remained oil analysis" conducted by the numerical simulation of 3D architectural-element model oil reservoir,the distributed modes of the remained oil in the high-sinuosity distributary-channel reservoir were summarized.The achievements show that within the channel,the remained oil are primarily distributed on the upper part of the point bar;while outside the channel,the remained oil are mainly on the top of the point bar and the blocked part by the abandoned channel,the dead-ends of the overbank sandbody and the isolated overbank sandbody with the inefficient injection-production system,and moreover the thin-bedded overbank sandbody with much poorer developed degree.

Abstract Superheated steam has a smaller density and a larger specific volume than conventional saturated steam, and has a stronger override effect in heavy oil reservoir. As most of heavy oil reservoirs have strong heterogeneity because of high porosity and permeability. Therefore, the steam injection profiles vary greatly and vertical producing degree of reservoirs is very low. Nitrogen with a large compression coefficient, large volume coefficient, large expansion volume capacity, can feed the formation energy and acceleratively drive heavy oil efficiently. For another, the surfactant in the foam can reduce the oil-water mobility ratio. High temperature-resistant gel can seal steam breakthrough channel due to its high permeability. Nitrogen foam and gel flooding can increase the superheated steam swept volume, improve the effect of superheated steam flooding in heavy oil thermal recovery. The injection parameters of nitrogen foam and high-temperature resistant gel were systematically studied by numerical simulation combined with physical simulation method in this paper. Gel, foaming agent, nitrogen injection sequence and injection method determined the improvement degree of steam injection profile modification. The results showed that under the injection rate of foaming agent was 240m3/d, the daily injection of nitrogen was 2000m3/d, the total injection amount of foaming agent was 16,000m3 in early slug injection, the effect of thermal recovery was the best. Application of this technology in KMK heavy oil field can enhance heat insulation effect of wellbore, decreased thermal lost by 15.5%, modified superheated steam injection profile by 36.3%, increased vertical producing degree of the reservoirs to 65.8%, feed formation energy in high efficiency. The superheated steam injection profile modification method by N2 foam and gel shows great economic prospect as a way of plugging steam breakthrough channel, controlling steam override and enhancing heavy oil recovery.

Based on the study of large-scale tight sand gas field in Groundbirch,Canada,this paper presents five properties for evaluation and analysis in tight gas development process,proposes the key parameters of tight-gas reservoir characterization,and determines the quantitative characterization and evaluation techniques applicable for tight gas reservoir in study area.Thus,a set of index system has been formed and includes multi-cycle fine isochronous stratigraphic framework and the analysis technique of sand-body superimposition structure characteristics for outlining reservoir distribution,the geostatistical quantitative technique of TOC logging parameters for obtaining organic matter abundance,the calibration technique of core "four-property" correlation and the quantitative characterization technique of reservoir properties based on sequential Gaussian simulation method for determining reservoir property classification level,the comprehensive discrimination technique of rock brittleness index based on core stress test and logging interpretation for determining rock compressibility,the integrated evaluation technique of multiple parameter assemblages related with the production of fracturing horizontal well for identifying favorable well blocks,the subsurface micro-seismic monitoring technology applicable to quantitatively characterize artificial fractures and optimize well arrangement,the optimizing technique of horizontal multi-stage fracturing for determining optimal fracturing member quantity,fracture spacing and other parameters as well as the single-well control volume and reserve of staged fracturing horizontal wells.The comprehensive research on reservoirs and fractures achieves the constant optimization of exploratory well pattern in tight gas reservoir,and the large-scale horizontal fracturing production is an effective way to guarantee high tight-gas production.These techniques have remarkable application effects in field.

In order to resolve this problem about how to consider and optimize several factors such as production,investment,revenue and risk and so on under the situation of overseas complex contract mode and changeable operating environment,a multi-objective optimization model is built for the CNPC overseas projects.In this model,both the time dimension and the risk factor are taken into account and the intricate business rules and constraints in the overseas contract models are mathematically characterized.And a hybrid optimization method which is combined by the "rank & cut" method,linear planning and genetic algorithms is developed and put forward for this multi-objective model.The hybrid method starts with the "rank & cut" method and the best portfolio generated by it is used to set constraints for the linear planning.And the genetic algorithm is used to seek the alternative portfolios near the local optimum solution generated by linear planning.This method is applied and verified during the optimization and planning process of CNPC overseas oil & gas projects.Therefore,it is of great significance to carry out planning and design optimization for overseas projects by these provided solutions and methods.

Reservoir architecture research of braided sandbodies plays an important role in predicting remaining oil distribution.However,the current research stays more on one general braided river mode but less on different types of braided river modes.On the basis of literature surveys and outcrop observations,studies are done respectively in two types of braided rivers,branching-based and wandering-based braided rivers.Taking FN field,Sudan as an example,following the idea of "hierarchical constraint,pattern fitting and multidimension proofs",a lot of research has been done to reveal the architecture differences between these two kinds of braided rivers based on cores and logging data.Firstly the extents of architectures are studied hierarchically,such as sands in single channel stream,intercalations either between two single channel streams or inside channel bars,and small-scaled channels inside channels bars;Secondly the scale relationships between channel bars and channels are computed.Meanwhile,the developing modes of intercalations and small-scaled channels are summarized.Finally the effects of different architectures on remaining oil distribution are discussed.The study shows that the sand thickness in branching-based braided river is larger than that in wandering-based braided river and the interlayer between two single braided streams in branching-based braided river is more stable than that in wandering-based braided river;that both of the two types braided rivers develop similar channel bars and channels in scale and shape;that channel bars are cut completely by the channels in branching-based braided river and the inside of the channel bar easily develops intercalations and small-scale channels which are either isolated or cross-distributed;and that in wandering-based braided river channel bars cannot be cut fully by channels which usually are small scale and intercalations in this kind of river develop relatively rare.All of these help to explore the vertical and lateral effects of architecture elements on remaining oil distribution,including five configurations of intercalations and recognitions of residual oil area like the bar edge,channel semi-filled by shale and so on.

中国石油实施海外油气资源战略20多年来取得了巨大成绩,已基本建成全球五大油气合作区.当前国际形势复杂多变,油价持续低迷,国内新常态下经济增速放缓,中国石油下一步海外资源战略该怎样走,已成为迫切需要研究和思考的问题.中国石油过去实施海外资源战略过度集中在高风险国家,而且多数项目将面临合同到期等严峻挑战.建议中国石油海外资源新战略应以“一带一路”沿线油气资源全产业链深度合作为战略重点,积极推进“中国-中亚-俄罗斯油气资源自供给体系”建设,积极审慎地获取低风险国家油气资产,平衡海外油气资源结构.

Injecting CO2 into reservoir has been proven to be not only a feasible method for improving ultimate oil recovery, but also reducing CO2 emissions and greenhouse effects. In this paper, the advantages of optimisation algorithm and numerical simulation are combined to establish mathematics model of production optimisation of water-alternate-gas (WAG) flooding. Augmented Lagrange function (ALF) and logarithm transformation (LT) are applied to convert constrained problems into unconstrained ones. The ensemble optimisation algorithm (EOA) is used to solve the latter. Then, the optimisation technology of reservoir production is formed. The optimisation technology is applied in a low permeability oil reservoir to test its feasibility of improving oil production. The results indicate that the CO2 swept efficiency, miscible region and recovery, can be effectively improved by the optimisation technology which increases the economic benefit of the reservoir.

To solve the problem of how to evaluate the effect of water flooding in oil fields fast and scientifically, this paper introduces a new evaluation method using radar chart approach into the evaluation work on water flooding's effect in the first time. The water flooding's effects in four typical overseas oil fields are been quantitatively and comprehensively evaluated and ranked by using the improved radar chart approach. The application of this fast evaluation method shows that the results gained through it is intuitionistic and effective and this method is helpful to the evaluation of water flooding's effect and making development strategy in the next step. Thus, it can be used as a comprehensive evaluation method of water flooding 's effect in the production process.