Prediction of petroleum exploration risk and subterranean spatial distribution of hydrocarbon accumulations

Investigation of spatial distribution of oil and gas resource and accurate prediction of the geographic location of its undiscovered resource is significant for reducing exploration risk and improving exploration benefit.A new method for predicting spatial distribution of oil resource is discussed in this paper.It consists of prediction of risk probability in petroleum exploration and simulation of hydrocarbon abundance. Exploration risk probability is predicted by multivariate statistics,fuzzy mathematics and information processing techniques.A spatial attribute database for sample wells was set up and the Mahalanobis distance and Fuzzy value of given samples were obtained.Then,the Bayesian formula was used to calculate the hydrocarbon-bearing probability at the area of exploration wells.Finally,a hydrocarbon probability template is formed and used to forecast the probability of the unknown area. The hydrocarbon abundance is simulated based on Fourier integrals,frequency spectrum synthesis and fractal theory.Firstly,the fast Fourier transformation(FFT) is used to transform the known hydrocarbon abundance from the spatial domain to the frequency domain,then,frequency spectrum synthesis is used to produce the fractal frequency spectrum,and FFT is applied to get the phase information of hydrocarbon-bearing probability.Finally,the frequency spectrum simulation is used to calculate the renewed hydrocarbon abundance in the play. This method is used to predict the abundance and possible locations of the undiscovered petroleum accumulations in the Nanpu Sag of the Bohai Bay Basin,China.The prediction results for the well-explored onshore area of the northern Nanpu Sag agree well with the actual situations.For the less-explored offshore areas in the southern Nanpu Sag,the prediction results suggest high hydrocarbon abundance in Nanpu-1 and Nanpu-2,providing a useful guiding for future exploration.     

Boiling Point Distribution of Hydrocarbon Types in Diesel Using Solid-Phase Extraction Followed by GC/FID-EIMS

In this paper, a method was established to determine the boiling point distribution of hydrocarbon types in diesel. The diesel sample was separated into the saturate and aromatic fractions by means of solid-phase extraction （SPE）, and each fraction was analyzed by GC/FID-EIMS. According to the relationship between boiling point and retention time of n-paraffins in the chromatogram, the percentages of saturates and aromatics at each temperature interval were calculated. According to the average mass spectra of the saturate and aromatic fractions at each temperature interval, the hydrocarbon types of the sample were identified through summation of characteristic mass fragments. Using this method, the changes in composition of diesel during hydrotreating process were studied. The results showed that hydrogenation of aromatics is the main reaction during the hydrotreating process. The more rings the aromatics have, the easier the hydrogenation reactions would take place. The aromatics were converted into cycloparaffins via the hydrogenation and saturation process, leading to an increase in low boiling point fractions in the hydrotreated oil.     

Novel empirical correlations for estimation of bubble point pressure, saturated viscosity and gas solubility of crude oils

Knowledge of petroleum fluid properties is crucial for the study of reservoirs and their development. Estimation of reserves in an oil reservoir or determination of its performance and economics requires a good knowledge of the fluid physical properties. Bubble point pressure, gas solubility and viscosity of oils are the most important parameters in use for petroleum and chemical engineers. In this study a simple-to-use, straight-forward mathematical model was correlated on a set of 94 crude oil data. Three correlations were achieved based on an exponential regression, which were different from conventional empirical correlations, and were evaluated against 12 laboratory data other than those used for the regression. It is concluded that the new exponential equation is of higher precision and accuracy than the conventional correlations and is a more convenient mathematical formulation.     

A static resistance model and the discontinuous pattern of hydrocarbon accumulation in tight oil reservoirs

In exploration for tight oil, the content and saturation of hydrocarbon in the tight reservoir is a key factor for evaluating the reserve. Therefore, it is necessary to study the geological history of hydrocarbon accumulation and the tight oil charging process. However, kinetic models used for petroleum development are not applicable for petroleum exploration. In this study, a static resistance model[ is proposed after analyzing resistances in ultra-slow flow in porous media. Using this model, the disco~atinuous pattern of oil charging is reproduced through incompressible Navier-Stokes equations, the phase field method and the finite element method. This study also explains macroscopic percolation behavior with microscopic flow mechanisms and discusses some issues in ultra-slow flow in a micro/nano pore-throat network. The resistance analysis reveals that capillary resistance and dissipation resistance are dominant factors in the mechanism of oil accumulation in tight reservoirs. Numerical simulations show that pressure thresholds exist and result in discontinuous oil charging. Generally, it is proven that the static model is more applicable than kinetic models in describing oil accumulation in tight reservoirs.     

Flow Characteristics of Crude Oil with High Water Fraction during Non-heating Gathering and Transportation

In order to ensure the safety of the non-heating gathering and transportation processes for high water fraction crude oil,the effect of temperature,water fraction,and flow rate on the flow characteristics of crude oil with high water fraction was studied in a flow experimental system of the X Oilfield.Four distinct flow patterns were identified by the photographic and local sampling techniques.Especially,three new flow patterns were found to occur below the pour point of crude oil,including EW/O&W stratified flow with gel deposition,EW/O&W intermittent flow with gel deposition,and water single-phase flow with gel deposition.Moreover,two characteristic temperatures,at which the change rate of pressure drop had changed obviously,were found during the change of pressure drop.The characteristic temperature of the first congestion of gel deposition in the pipeline was determined to be the safe temperature for the non-heating gathering and transportation of high water cut crude oil,while the pressure drop reached the peak at this temperature.An empirical formula for the safe temperature was established for oil-water flow with high water fraction/low fluid production rate.The results can serve as a guide for the safe operation of the non-heating gathering and transportation of crude oil in high water fraction oilfields.     

Petroleum geology features and research developments of hydrocarbon accumulation in deep petroliferous basins

As petroleum exploration advances and as most of the oil–gas reservoirs in shallow layers have been explored, petroleum exploration starts to move toward deep basins, which has become an inevitable choice. In this paper, the petroleum geology features and research progress on oil–gas reservoirs in deep petroliferous basins across the world are characterized by using the latest results of worldwide deep petroleum exploration. Research has demonstrated that the deep petroleum shows ten major geological features.(1) While oil–gas reservoirs have been discovered in many different types of deep petroliferous basins, most have been discovered in low heat flux deep basins.(2) Many types of petroliferous traps are developed in deep basins, and tight oil–gas reservoirs in deep basin traps are arousing increasing attention.(3) Deep petroleum normally has more natural gas than liquid oil, and the natural gas ratio increases with the burial depth.(4) The residual organic matter in deep source rocks reduces but the hydrocarbon expulsion rate and efficiency increase withthe burial depth.(5) There are many types of rocks in deep hydrocarbon reservoirs, and most are clastic rocks and carbonates.(6) The age of deep hydrocarbon reservoirs is widely different, but those recently discovered are predominantly Paleogene and Upper Paleozoic.(7) The porosity and permeability of deep hydrocarbon reservoirs differ widely, but they vary in a regular way with lithology and burial depth.(8) The temperatures of deep oil–gas reservoirs are widely different, but they typically vary with the burial depth and basin geothermal gradient.(9) The pressures of deep oil–gas reservoirs differ significantly, but they typically vary with burial depth, genesis, and evolution period.(10) Deep oil–gas reservoirs may exist with or without a cap, and those without a cap are typically of unconventional genesis. Over the past decade, six major steps have been made in the understanding of deep hydrocarbon reservoir formation.(1) Deep petroleum in petroliferous basins has multiple sources and many different genetic mechanisms.(2) There are high-porosity,high-permeability reservoirs in deep basins, the formation of which is associated with tectonic events and subsurface fluid movement.(3) Capillary pressure differences inside and outside the target reservoir are the principal driving force of hydrocarbon enrichment in deep basins.(4) There are three dynamic boundaries for deep oil–gas reservoirs; a buoyancy-controlled threshold, hydrocarbon accumulation limits, and the upper limit of hydrocarbon generation.(5)The formation and distribution of deep hydrocarbon reservoirs are controlled by free, limited, and bound fluid dynamic fields. And(6) tight conventional, tight deep, tight superimposed, and related reconstructed hydrocarbon reservoirs formed in deep-limited fluid dynamic fields have great resource potential and vast scope for exploration.Compared with middle–shallow strata, the petroleum geology and accumulation in deep basins are morecomplex, which overlap the feature of basin evolution in different stages. We recommend that further study should pay more attention to four aspects:(1) identification of deep petroleum sources and evaluation of their relative contributions;(2) preservation conditions and genetic mechanisms of deep high-quality reservoirs with high permeability and high porosity;(3) facies feature and transformation of deep petroleum and their potential distribution; and(4) economic feasibility evaluation of deep tight petroleum exploration and development.     

Prediction of Interbeds Intercalated into Complex Heterogeneous Reservoirs at a High Water Cut Stage

The occurrence of interbeds in thick oil formations is one of the main reasons that cause the difference of remaining oil distribution. A quantitative method for predicting interbeds was proposed and the sedimentary origin and division criterion were demonstrated. The distribution of interbeds in different types of sedimentary sand bodies were predicted and analyzed by combining the theory of sedimentology and reservoir bed architectural-element analysis. The interbeds in a single well were recognized from high resolution well logs, and inter-well interbeds were predicted by using the methods of cyclothem correlation, physical properties truncation, and conditional simulation. Finally a 3-D model of interbed was built. Application to the Gudao Oilfield was successful.     

Genetic pattern of belt-wide petroliferous phenomenon in the eastern Pearl River Mouth Basin and its practical application

The Pearl River Mouth Basin(PRMB) covers an area of approximately 20×104 km2. However, oil-gas fields detected in this area thus far are highly concentrated and controlled predominantly by second-order structural belts, the seven largest of which aggregate proved oil reserves of 7.7×108 m3, accounting for 86% of the total discovered reserve in the basin. These second-order structures have one common phenomenon: oil is contained in all traps present in them. In other words, they are all belt-wide petroliferous reservoirs. Research has identified eight types of second-order structural belts under two categories in the eastern PRMB. Their petroliferous properties are subject to three typical constraints: petroliferous properties of subsags hosting these structural belts, locations of these belts in the petroleum system, and availability of traps prior to the hydrocarbon expulsion and migration. The formation and distribution of oil reservoirs in these belts are characterized by subsag–belt integration and "three-in-one". The former indicates that sags and the second-order structural belts within the supply range of the sags constitute the basic units of hydrocarbon accumulations and are therefore inseparable. The latter indicates that a belt-wide petroliferous second-order structural belt always contains three important elements: hydrocarbon richness, effective pathway and pre-existing traps.     

Identification of petroleum acids in Liaohe super-heavy oil

In this study,petroleum acids were extracted from the super-heavy oil of Liaohe oilfield,North-east China,by using acetic acid,and their structural components and properties were investigated by using FT-IR and MS.Moreover,the trace metal contents in the super-heavy oil sample before and after acetic acid treatment were also measured in this work.The results showed that naphthenic acids were the main component of petroleum acids in Liaohe super-heavy oil,and the content of naphthenic acids with double rings was higher than that of other naphthenic acids.It can be concluded that petroleum acids in Liaohe super-heavy oil mainly consist of naphthenic acids,with a carbon number of around 11-69 and containing one to six naphthenic rings and/or one to two aromatic rings,and mainly exists in form of metal salts of petroleum acid.The molecular weight of petroleum acids is in the range of 190-1000.     

Top 10 Technological Breakthroughs of CNPC in 2012

CNPC attaches great importance to technological research and development,and makes steady progress every year relying on the intelligence and diligence of its people. Major breakthrough in molecular geochemical tracing of complex oil/gas reservoir forming This important breakthrough addresses the difficulty in predicting hydrocarbon properties and understanding their enrichment levels and distribution laws in the key exploration areas of China,such as deep and ultra-deep,carbonate and unconventional reservoirs.It has provided a theoretical basis for quantitative evaluation of the potential of multi-source hydrocarbon accumulation,dynamic tracing of hydrocarbon generation-migrationaccumulation process and the related secondary changes,and effective prediction of the properties of major formations and hydrocarbon fluids.     

石油重馏分油临界性质预测方法的研究

重馏分油在达到其临界点前已发生热分解，因而不能测得其临界性质（临界温度和临界压力），经研究提出预测重馏分油临界性质的一种方法。选用监界温度高于６９１．８５Ｋ的已知的临界性质的８个纯烃，分别与苯配成不同组成的二元混合物，用半封闭管法测定混合物的监界性质，将此混合物与苯的临界性质和苯在混合物中的含量等数据，经数学处理得到纯烃临界性质的方法计算值的方法。将重馏分油视为虚拟发掺入苯，测定该混合物临界性质，     

MEASUREMENT AMD PREDICTION OF CRITICAL PROPERTIES OF CHINESE PETROLEUM FRACTIONS

The critical properties (T_c, P_c, V_c) of 102 virgin oil fractions from five Chinese crude oils were measured by sealed tube method and semi-sealed tube method using gallium as pressure transfer medium. Satisfactory correlations for predicting critical parameter with other easy-measured physical properties were measured. The feasibility of group contribution method for predicting critical parameters of the above mentioned oil fractions were also investigated.     

MEASUREMENT AMD PREDICTION OF CRITICAL PROPERTIES OF CHINESE PETROLEUM FRACTIONS

ABSTRACT

The critical properties (T_c, P_c, V_c) of 102 virgin oil fractions from five Chinese crude oils were measured by sealed tube method and semi-sealed tube method using gallium as pressure transfer medium. Satisfactory correlations for predicting critical parameter with other easy-measured physical properties were measured. The feasibility of group contribution method for predicting critical parameters of the above mentioned oil fractions were also investigated.     

超临界流体萃取分馏法分离石油重质油

石油渣油的分离和评价，对重质油加工技术水平的提高具有重要的指导作用。根据超临界流体萃取的基本原理，开发了一种以Ｃ３、Ｃ４、ｎ－Ｃ５或它们的混合物为溶剂的超临界流体萃取分馏方法和仪器，采取恒定温差线性升压的操作模式将石油重质油按性质的差异分离成窄馏分进行深入的研究，从而为石油重质油的合理有效地加工利用提供基础数据和信息。着重介绍该分离方法的原理、仪器、分离条件的研究及其在重质油分离中的应用。本方法可     

A new correlation for predicting the minimum miscibility pressure regarding the enhanced oil recovery processes in the petroleum industry

Miscible gas injection is a promising technique to enhance the oil recovery from petroleum reservoirs. Natural gas is usually injected because of consistency between the gas and reservoir fluid composition and accessibility of the injected fluid. In this work a new correlation is presented for accurate prediction of the required minimum miscibility pressure (MMP) for multicontact miscible displacement of reservoir petroleum by hydrocarbon gas injection. Accurate estimation of the MMP is required for optimal design of recovery systems and optimization of the production economics. It is shown that the presented correlation is very accurate and reliable for predicting the MMP over wide ranges of oil and gas compositions. Comparison of the suggested correlation with the most important existing correlations shows that the presented correlation outperforms the other alternatives both in accuracy and generality.     

Applying ANFIS-PSO algorithm as a novel accurate approach for prediction of gas density

The accurate estimations of processes in gas engineering need a high degree of accuracy in calculations of gas properties. One of these properties is gas density which is straightly affected by pressure and temperature. In the present work, the Adaptive neuro fuzzy inference system (ANFIS) algorithm joined with Particle Swarm Optimization (PSO) to estimate gas density in terms of pressure, temperature, molecular weight, critical pressure and critical temperature of gas. In order to training and testing of ANFIS-PSO algorithm a total number of 1240 experimental data were extracted from the literature. The statistical parameters, Root mean square error (RMSE), coefficient of determination (R²) and average absolute relative deviation (AARD) were determined for overall process as 0.14, 1 and 0.039 respectively. The determined statistical parameters and graphical comparisons expressed that predicting mode is a robust and accurate model for prediction of gas density. Also the predicting model was compared with three correlations and obtained results showed the better performance of the proposed model respect to the others.     

基准相态为气相的液态烃物理计算

指出了在石化企业中掌握在不同状态下轻烃类物理焓、熵及　计算方法的重要意义。从５个方面重点对基准相态为气相的液态烃焓、熵及的计算方法进行了详细的分析探讨：（１）在气相轻烃单体从基准状态被等温压缩至其饱和蒸气压而开始液化前的焓、熵及;（２）在可逆相变过程中的焓为该物质的蒸发潜热,在该相变过程中的焓、熵及;（３）把液相变压过程中的液相性质看成与压力无关;（４）在液相变温过程中轻烃单体的焓、熵及;（５）轻烃类混合物的焓、熵及。最后,以炼油过程中轻烃单体及其混合物物理　的计算作为实例来说明这些计算策略的应用。     

中国陆上深层油气资源勘探开发现状及展望

深层油气勘探开发近年来获得了一系列重大突破,但中国陆上深层油气资源勘探开发取得的进展、面临的挑战以及发展趋势尚无系统的分析。通过深入分析,概括了深层油气资源5点基本特征：①气多油少,相态类型复杂;②高温高压普遍,不同盆地或层系差异大;③多元供烃,多源复合;④储层相对致密,但发育规模中高效储层; ⑤成藏过程复杂,多期成藏改造。梳理了深层油气勘探开发的过程,认为中国深层油气勘探开发目前处于“规模发现阶段”,在深层碳酸盐岩、碎屑岩、火山岩三大领域都取得了重大进展,但仍面临4方面挑战,主要表现为：①生烃、成储、成藏过程复杂,制约了勘探方向与目标选择;②钻完井周期长成本高,制约油气发现进程与效益开发;③高温压小井眼测井技术不成熟,制约了油气层识别精度;④开发方式及采油采气技术装备不适应,制约了有效开发和规模动用。在综合分析的基础上,指出中国陆上深层油气资源集中于三大领域六大盆地,勘探潜力巨大,是重要的油气资源战略接替领域,建议集中相关油气公司、石油院校及科研单位研究力量,攻克制约深层发展的重大基础理论和共性技术难题,集成涉及深层领域相关成果,构建深层油气勘探开发理论、技术体系,支撑深层领域快速发展。     

Ӧ��һ���µ�����ѹ����ƽ�ⳣ����ⷽ������������ϵ��̬����

本文根据溶解度参数规则，将石油烃类体系划分为六个拟二元体系的组合，在此基础上，建立了一种新的收敛压力求解方法。并依据Grayson-streed规则和临界指数理论推证了一种具有一定理论基础的分段求解平衡常数的新方法，然后应用此方法编制了具有收敛压力、平衡常数、露点、泡点、闪蒸计算等五种功能的计算软件，并进行了两个实际油气体系的平衡常数和W72井的相态计算。结果表明，这种方法切实可行。     

Utilization of Fuzzy C-means algorithm as a novel predictive tool for estimation of interfacial tension of hydrocarbon and brine

The interfacial tension that exists between brine and hydrocarbon is known as one of major properties in petroleum industries because it extremely affects oil trapping in reservoirs and consequently oil recovery. Due to aforementioned reasons the importance of investigation of this parameter has been highlighted. In the present study, Fuzzy C-means (FCM) algorithm was developed to predict interfacial tension between hydrocarbon and brine as function of different parameters such as pressure, temperature, carbon number of hydrocarbon and ionic strength of brine. The obtained results of predicting algorithm expressed its low relative error and deviation from the experimental data which gathered from the literature. Also the coefficients of determination (R²) for training and testing data were calculated 0.9508 and 0.9309 respectively. This predictive tool is simple and user friend to utilize and can be helpful for petroleum engineers to estimate interfacial tension between hydrocarbons and brine.