Field Of Petroleum Exploration Research Articles

A novel method for favorable zone prediction of conventional hydrocarbon accumulations based on RUSBoosted tree machine learning algorithm

The prediction of favorable zone (FZ) is the most important step for conventional hydrocarbon accumulations (CHAs) exploration. Recently, the method of coupling multiple hydrocarbon accumulation (HA) elements is widely used to predict the distribution of FZ in the petroleum exploration field. However, the forming mechanism of CHAs is extremely complicated, which causes difficulty in accurately describing the relationship between multiple HA elements and HA probability (HAP). Hence, it is difficult to predict the distribution of FZ quantitatively and credibly using traditional methods. This study proposes a method for predicting FZ for CHAs based on random undersampling boosted (RUSBoosted) tree machine learning (ML) algorithm. First, the characteristics of data in the petroleum exploration field are clarified, and a suitable ML algorithm is selected. Second, the theory and knowledge of the petroleum exploration field is integrated into the data, a HAP prediction model for CHAs is constructed, and then the method for FZ prediction is proposed. Further, the method is applied to Jin 93 Well Block for predicting FZ of CHAs. Finally, this study discussed the difference in performance among models constructed by the RUSBoosted tree and other five ML algorithms and the difference in training results between the original geological data and preprocessed geological data on the RUSBoosted tree ML algorithm. Results show that, currently, datasets in the petroleum exploration field are small and unbalanced, and the RUSBoosted tree ML algorithm has excellent training results on it. Compared with the original geological data, the performance of the HAP prediction model constructed by preprocessed geological data is improved. On a Jin 93 Well Block dataset, the HAP prediction model constructed by the RUSBoosted tree ML algorithm belongs to a good prediction model, and FZ of CHAs predicted by this HAP prediction model agree well with CHAs discovered areas. The results of this study provide an idea for intelligently predicting the distribution of FZ of CHAs and are of great significance to the development of intelligent petroleum exploration technology.

Medium and low frequency fiber Bragg grating acceleration sensor based on single-sided single-arc hinge

A medium and low frequency fiber Bragg grating (FBG) based acceleration sensor based on single-axis single-arc hinge-shaped sensitization structure is designed and experimentally demonstrated. The theoretical formula of the sensor's resonance frequency and sensitivity was given, the stress distribution, characteristic frequency and amplitude frequency characteristics of the sensor were simulated and the structural parameters of the sensor were optimized. The experimental results show that the resonance frequency of the sensor is 630 Hz, the flat frequency range is 30–300 Hz, and the acceleration sensitivity is 57.77 pm/g. The sensor has the advantages of high sensitivity, wide flat frequency range and strong transverse anti-interference ability, which can meet the requirements of acceleration detection in petroleum exploration field.

Review of research on big data technology in the field of petroleum exploration

In the era of big data, the rich data resources of the petroleum industry not only provide auxiliary decision-making support for the production and scientific research of petroleum enterprises, but also play a vital role in the digital transformation of enterprises. From the perspective of petroleum exploration data management technology, this paper divides its past development process into database technology stage, data warehouse technology stage, data lake technology stage, data integration platform stage, and special application of big data technology by combing the relevant literature. At present, it is in the initial stage of the construction of the data middle office. The core problem that needs to be solved is to match the calculation type with the most suitable computing framework, optimize the allocation of computing resources, and give full play to the processing capabilities of the data middle office.

Predicting collapse depth of paleocaves in carbonate reservoirs

Paleocaves in carbonate reservoirs are the excellent oil and gas storage spaces in the field of petroleum exploration. Predicting the collapse depth of paleocaves in carbonate reservoirs has essential theoretical significance and applicable value for classifying of reservoir quality and delimiting lower depth of oil and gas exploration. Paleocaves in carbonate reservoirs are acted by overburden pressure, tectonic lateral compression, and fluid pressure in caves. In this study, paleocaves with irregular boundary shapes were abstracted as spheres with different diameters. Mechanical model of surrounding rocks of paleocaves was established to compute the stress states in 3–5 times diameter of caves. Through analyzing stress states in surrounding rocks, the destruction and collapse of caves was investigated. The diameters of caves in these models range from 0.01 mm to 10 m. Relationship between diameter of cave and collapse depth was obtained by fitting collapse depth of caves with different diameters. Above the collapse depth of caves with diameter 5 m is good reservoir zone. Between the collapse depth of caves with diameter 5 m and 2 m is effective reservoir zone. The interval of collapse depth of caves with diameter 2 m and 0.5 m is general reservoir zone. Below 11000 m, karst caves in carbonate reservoir nearly disappear. Numerical model of real paleocaves was established to simulate the deformation of single paleocave and paleocave group. The relationship between displacement of paleocave wall and depth of paleocave obeyed power law. The contiguous destruction and collapse occurred first between the paleocaves with small distance. The relationship can be used to classify the quality of carbonate reservoir and predict the lower depth of petroleum exploration.

Review of Research on Big Data Technology in the Field of Petroleum Exploration

In the era of big data, the rich data resources of the petroleum industry not only provide auxiliary decision-making support for the production and scientific research of petroleum enterprises, but also play a vital role in the digital transformation of enterprises. From the perspective of petroleum exploration data management technology, this paper divides its past development process into database technology stage, data warehouse technology stage, data lake technology stage, data integration platform stage, and special application of big data technology by combing the relevant literature. At present, it is in the initial stage of the construction of the data middle office. The core problem that needs to be solved is to match the calculation type with the most suitable computing framework, optimize the allocation of computing resources, and give full play to the processing capabilities of the data middle office.

Current Status and Development Trend Analysis of Neutron Logging in Uranium Mines in China

Neutron logging is a method of measuring uranium fission neutrons by bombarding uranium in ore beds with neutrons emitted by neutron sources or neutron generators. The pulsed neutron logging technology of uranium ore has been popularized and applied in the United States, Russia, Australia and other countries. The key technology is almost monopolized by these countries, but the technology is prohibited in China. In the field of uranium logging, natural gamma logging has always been used in China for uranium quantification, which is characterized by large error, low efficiency, high cost and technical and economic bottlenecks. Due to the fact that the research and application of pulsed neutron log in the field of petroleum exploration and production is relatively mature in China, it is urgent to develop relevant logging instruments and uranium quantitative interpretation methods as independent intellectual property rights. This will lead to a change in the backward appearance of uranium logging. This paper analyzes the research status and development trend of neutron logging in uranium at home and abroad.

Development of water sensitivity index of loess from its mechanical properties

Loess is a typical soil with the characteristic of water sensitivity, and in the study of water-induced geological disasters of loess distribution areas worldwide, special attention must be paid to the influence of this sensitivity. Hence, quantitative study of the water sensitivity of loess has been a basic scientific issue of wide concern. In this study, the water sensitivity characteristics of loess in the South Jingyang Tableland of China are investigated through oedometer tests and triaxial shear tests, and the variation in the structural strength, deformation modulus, and strength parameters of intact samples with different water contents is studied. It is found that the structural yield stress, initial deformation modulus and cohesion are sensitive to the water content, i.e., decreasing in the form of a power function or an exponential function with increasing initial water content. An analysis shows that the above parameters can be used to normalize the compression curves, stress-strain curves and critical state lines of loess. According to the quantitative formula of water sensitivity in the field of petroleum exploration, a new method to assess the water sensitivity of loess by analogy is proposed, which involves the structural strength, deformation modulus and shear strength parameters in the natural and humidified states. The analysis further indicates that the water sensitivity index proposed in this paper is a reasonable, sensitive and effective way to quantify the water sensitivity of loess.

Research on Application of Image Enhancement Technology in Automatic Recognition of Rock Thin Section

Artificial intelligence technology has rapidly emerged in various new industries due to its high efficiency and has been successfully used in many fields. However, it has been slow to start in the field of petroleum exploration, under the background of the need for more efficient exploration and development in the petroleum field. In this paper we used the ResNet-18 convolutional neural network to make an attempt to automatically identify rock thin section, and finds that this method can efficiently identify rock thin section and has a higher accuracy rate. In addition, we adopted appropriate image enhancement technology, which can significantly improve the recognition accuracy of the model. It proves that related machine learning technology has broad application prospects in the fields of petroleum exploration and petroleum geology.

Why Do Institutions Revert? Institutional Elasticity and Petroleum Sector Reforms in India

The institutional change literature has predominantly focused on successful changes and sparsely on failed changes, but the idea of institutional fields reverting to their pre-change or near pre-change state, after change attempts, remains underexplored. Although recent studies have explored similar phenomenon from the perspective of actors resisting change and trying to restore status quo, a field-level understanding of the processes and the dynamics associated with it remains underexamined. The present study, using the case of reforms in the field of petroleum exploration and production in India, examines an institutional change where the institution, once modified, gradually reverted near to its prechange state. We suggest the concept of institutional elasticity to explain such reverting of institutions, and elaborate on three boundary conditions—scope of change, pace of change, and field-level actor constellations—which have implications for the relationship between institutional elasticity and reverting of institutions.

Sequence stratigraphic division of the Shisanlitai Formation of Neoproterozoic in Southern Liaoning, China

Sequence stratigraphy is the most important prediction theory in the field of petroleum exploration, and is hailed as a theoretical revolution in geology. At present, countries around the world have begun to pay attention to the study of marine carbonate rocks. The Shisanlitai Formation in Dalian, Liaoning is an important Neoproterozoic stratum in China, with a large number of carbonate rocks. Through comprehensive analysis of the field measured profiles, the sequence stratigraphy of the Shisanlitai Formation was studied. A total of 4 sequence boundary were identified, and 3 sequence, 7 para-sequence sets and 20 para-sequences were divided. It is considered that the Shisanlitai Formation is a platform marginal sedimentary facies. The regional geotectonic and astronomical cyclic methods are used to discuss the environmental evolution of the Ganjingzi Formation. Platform marginal beach → platform marginal slope → platform marginal reef evolution process, and summarized that there were 4 short exposures from the end of the Majiatun period to the Shisanlitai Formation period in the Dalian area affected by the low-amplitude tectonic ups and downs in the late Yangtze cycle 4 sequence boundary and 3 sequences are formed. Through comprehensive and systematic analysis of the sequence stratigraphy and sedimentary evolution of the Shisanlitai Formation, it provides a basis for exploring the oil and gas resources in southeastern Liaoning.

Estimation of permeability and saturation based on imaginary component of complex resistivity spectra: A laboratory study

Abstract Low-frequency resistivity logging plays an important role in the field of petroleum exploration, but the complex resistivity spectrum of rock also contains a large amount of information about reservoir parameters. The complex resistivity spectra of 15 natural sandstone cores from western China, with different water saturations, were measured with an impedance analyzer. The pore space of each core was saturated with NaCl solution, and measurements were collected at a frequency range of 40–15 MHz. The results showed a linear relationship between the real resistivity at 1 kHz and the maximum values of imaginary resistivity for each core with different water saturations. The slopes of the linear best-fit lines had good linear relationships with the porosity and the permeability of cores. Based on this, a permeability estimation model was proposed and tested. In addition, the maxima of imaginary resistivity had power exponential relationships with the porosity and the water saturation of the cores. A saturation evaluation model based on the maxima of imaginary resistivity was established by imitating Archie’s formula. The new models were found to be feasible for determining the permeability and saturation of sandstone based on complex resistivity spectrum measurements. These models advance the application of complex resistivity spectrum in petrophysics.

Semi-supervised learning for lithology identification using Laplacian support vector machine

Lithology identification is a fundamental task in well log interpretation. Considering the presence of substantial unlabeled data in the field of petroleum exploration, this paper investigates the semi-supervised learning method for lithology identification, and proposes a semi-supervised lithology identification workflow. In the workflow, the Laplacian support vector machine is employed to achieve semi-supervised learning. The feature similarity and depth similarity are introduced to reveal the data distribution characteristic, thus enabling us to elevate the classification performance of the Laplacian support vector machine dealing with the issue of lacking labels. Considering the well logging dataset without label, K-means clustering is used to select the k well logging samples that should be labeled by experts, based on which Laplacian support vector machine algorithm can be then conducted. The proposed method is compared with the supervised method (e.g., support vector machine) that excludes the unlabeled data and the semi-supervised method without considering the depth similarity. The comparison experiments are conducted on four datasets that are collected from the Jiyang Depression, Bohai Bay Basin, China. The experimental results show that the utilization of unlabeled data can improve identification performance, especially that of minority lithology classes. It is also verified that the information provided by feature similarity and depth similarity are helpful for lithology identification.

Editorial Note for Journal of Petroleum and Environmental Biotechnology

Journal of Petroleum & Environmental Biotechnology is the most preferred and highly accessed Journal in the field of petroleum exploration, production and environmental biotechnology. The Journal is indexed in CAS Source Index (CASSI), Index Copernicus and Scholar among many other reputed scientific databases. In fact, Journal of Petroleum & Environmental Biotechnology encourages editorial board members to actively contribute to the scientific world from their research globally. All scientific manuscripts including editorials are subjected to peer review. J Pet Environ Biotechnol follows a double blind peer review process where identity of authors and reviewers is not revealed to each other.

Experimental study of the influence of oil-wet calcite cements on oil migration and implications for clastic reservoirs

The influence of oil-wet calcite cements on oil migration in clastic reservoirs is of significant interest in the field of petroleum exploration. However, the microscopic migration of oil in microscopic pore spaces with oil-wet calcite cements has not been directly observed. Microscopic observations of oil migration were conducted in a glass micromodel at normal temperature and pressure to investigate the influence mechanism of oil-wet calcite cements on oil migration in pore spaces. The calcites were precipitated as cements prior to the oil migration. A two-dimensional glass micromodel with two interconnected spaces with the same pore throat structures was used in the experimental study. A new method to create firmly adhering calcites was used to precipitate equal amounts of calcites in the two interconnected spaces. The oil migration was recorded in real-time under a microscope throughout the experiment. The experimental results show that oil migration occurs faster in spaces with than without oil-wet calcites. During the oil migration in the pore-throat spaces, the oil migrates towards the surfaces of the oil-wet calcites when the oil is in contact with the calcites. The presence of oil-wet calcites significantly reduces the oil breakthrough pressure. The electrostatic attraction between the carboxylic groups and calcites and the intermolecular forces between the carboxylic groups and organic molecules in the oil cause the oil migration towards the surfaces of the oil-wet calcites. The experimental results indicate that oil preferentially migrates into clastic reservoirs that possess appropriate amounts of oil-wet calcite cements precipitated prior to oil emplacement.

Quantitative Prediction of Fracture Distribution of the Longmaxi Formation in the Dingshan Area, China using FEM Numerical Simulation

Fracture prediction is a technical issue in the field of petroleum exploration and production worldwide. Although there are many approaches to predict the distribution of cracks underground, these approaches have some limitations. To resolve these issues, we ascertained the relation between numerical simulations of tectonic stress and the predicted distribution of fractures from the perspective of geologic genesis, based on the characteristics of the shale reservoir in the Longmaxi Formation in Dingshan; the features of fracture development in this reservoir were considered. 3D finite element method (FEM) was applied in combination with rock mechanical parameters derived from the acoustic emissions. The paleotectonic stress field of the crack formation period was simulated for the Longmaxi Formation in the Dingshan area. The splitting factor in the study area was calculated based on the rock breaking criterion. The coefficient of fracture development was selected as the quantitative prediction classification criteria for the cracks. The results show that a higher coefficient of fracture development indicates a greater degree of fracture development. On the basis of the fracture development coefficient classification, a favorable area was identified for the development of fracture prediction in the study area. The prediction results indicate that the south of the Dingshan area and the DY3 well of the central region are favorable zones for fracture development.

The influence of core holder output port on core internal fluid flow

ABSTRACTCore holder is a common experimental device in the field of petroleum exploration. Each kind of core holder has an output port. The objective of this paper is to determine whether the output port will affect the fluid flow in the core. The function of the output port is to collect and derive the fluid. A compression ring with a thickness of 5 mm and a diameter of 25 mm was fabricated by using 3D printing technology. We add the ring between the rock sample and the output port. The ring does not affect the function of the output port but avoids direct contact between the output port and the core end face. We find that permeability test results obtained by adding a ring are larger than that obtained by the core holder without a ring. A numerical simulation model is established according to the size of the output port. The influence of the output port on the velocity and pressure distribution in the rock sample is analyzed by using the coupling of Stokes and Darcy flow numerical simulation method. It is pointed out that the output port affects the fluid flow within 5 mm near the end face of the rock sample. The fluid velocity is unstable in the range of 5 mm near the end face of the rock sample. In order to reduce the influence of the output port on fluid flow in the core, five new types of output port grooves are designed in this paper. Comparing the numerical simulation results of different grooves schemes, it is considered that adding a 5 mm cylindrical cavity between the output port and the rock sample can reduce the influence. It is suggested that the output port should not be in direct contact with the core, and the output port and the end face of the core should be separated by 5 mm.

Lithofacies paleogeography mapping and reservoir prediction in tight sandstone strata: A case study from central Sichuan Basin, China

Sand-rich tight sandstone reservoirs are potential areas for oil and gas exploration. However, the high ratio of sandstone thickness to that of the strata in the formation poses many challenges and uncertainties to traditional lithofacies paleogeography mapping. Therefore, the prediction of reservoir sweet spots has remained problematic in the field of petroleum exploration. This study provides new insight into resolving this problem, based on the analyses of depositional characteristics of a typical modern sand-rich formation in a shallow braided river delta of the central Sichuan Basin, China. The varieties of sand-rich strata in the braided river delta environment include primary braided channels, secondary distributary channels and the distribution of sediments is controlled by the successive superposed strata deposited in paleogeomorphic valleys. The primary distributary channels have stronger hydrodynamic forces with higher proportions of coarse sand deposits than the secondary distributary channels. Therefore, lithofacies paleogeography mapping is controlled by the geomorphology, valley locations, and the migration of channels. We reconstructed the paleogeomorphology and valley systems that existed prior to the deposition of the Xujiahe Formation. Following this, rock-electro identification model for coarse skeletal sand bodies was constructed based on coring data. The results suggest that skeletal sand bodies in primary distributary channels occur mainly in the valleys and low-lying areas, whereas secondary distributary channels and fine deposits generally occur in the highland areas. The thickness distribution of skeletal sand bodies and lithofacies paleogeography map indicate a positive correlation in primary distributary channels and reservoir thickness. A significant correlation exists between different sedimentary facies and petrophysical properties. In addition, the degree of reservoir development in different sedimentary facies indicates that the mapping method reliably predicts the distribution of sweet spots. The application and understanding of the mapping method provide a reference for exploring tight sandstone reservoirs on a regional basis.

Palynology and Petroleum Exploration: ABSTRACT

During the past decade, the relatively new science of palynology has generated considerable interest in the field of petroleum exploration. Many geologists have not yet become familiar with palynology and its great potential in stratigraphic, paleogeographic, paleoecologic, and paleoclimatologic studies. After a brief sketch of the development of palynology and the amount of activity in this field at present, some of the basic principles are presented and examined in detail. During the examination of these principles, their potential value to the field of geology is illustrated. Among the important problems facing exploration geologists are the following: (1) age dating of sediments, (2) correlation of contemporaneously deposited sediments, and (3) depositional environmen of sediments. Palynology can give valuable data in all three of these areas. Emphasis is placed on some of the recent correlations established on the basis of palynological work as well as some of the recent findings concerning age determinations. In view of the fact that palynology is such a young field, some of the problems confronting palynologists are discussed as well as certain areas of this field that are relatively unexplored. End_of_Article - Last_Page 406------------

On: Magnetic Interpretation by D. Wantland

In the field of petroleum exploration, progress in the technique of interpretation of magnetic surveys appears to be following to a great extent the recognition and application of the fact that variations in the magnetic susceptibility of sedimentary formations may cause mappable variations in the magnetic intensity of the earth’s field.