Integrated processing and interpretation to image and derisk a carbonate reservoir clouded by shallow gas — A case study from offshore Vietnam

2021 ◽  
Vol 40 (5) ◽  
pp. 357-364
Author(s):  
Jaewoo Park ◽  
Craig Hyslop ◽  
Da Zhou ◽  
Arjun Srinivasan ◽  
Patricia Montoya ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Model Building ◽  
Integrated Approach ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Shallow Gas ◽  
Hydrocarbon Production ◽  
Field Development ◽  
Processing Depth ◽  
Seismic Image

Carbonate reservoirs are increasingly becoming an important resource for hydrocarbon production because they contain the majority of remaining proven oil and gas reserves. In this context, carbonate reservoirs could represent new opportunities; however, there is still a lack of understanding of their subsurface status and characterization. Carbonate reservoirs are more difficult to evaluate than their siliciclastic counterparts because many aspects of carbonate rocks make their seismic image signature complex and difficult to interpret. Moreover, the presence of complex overburden such as shallow gas accumulation can exacerbate amplitude and phase fidelity at the reservoir, which introduces an additional imaging challenge. This makes field development of carbonate reservoirs extremely difficult because field development requires detailed delineation of characteristic karst features to avoid drilling hazards and sudden water breakthrough. In this paper, we demonstrate that a tight integration of signal processing, depth model building, and imaging, as well as near-real-time seismic interpretation feedback, is the key to success for imaging complex carbonate reservoirs with overburden challenges. Our findings show that such an integrated approach can result in a substantially better image, reduced depth uncertainty, and better delineation of karst and fractures. It can also aid in well placement and improve reservoir property modeling.

scholarly journals Formation environments and mechanisms of multistage paleokarst of Ordovician carbonates in Southern North China Basin

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Haitao Zhang ◽  
Guangquan Xu ◽  
Mancai Liu ◽  
Minhua Wang
Keyword(s):  
Carbonate Rocks ◽  
North China ◽  
Oil And Gas ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Geochemical Data ◽  
Near Surface ◽  
Oil And Gas Exploration ◽  
Pore Types ◽  
North China Basin

AbstractWith the reduction of oil and gas reserves and the increase of mining difficulty in Northern China, the carbonate rocks in Southern North China Basin are becoming a significant exploration target for carbonate reservoirs. However, the development characteristics, formation stages, formation environments and mechanisms of the carbonate reservoirs in Southern North China Basin are still unclear, which caused the failures of many oil and gas exploration wells. This study focused on addressing this unsolved issue from the Ordovician carbonate paleokarst in the Huai-Fu Basin, which is located in the southeast of Southern North China Basin and one of the key areas for oil and gas exploration. Based on petrology, mineralogy and geochemical data, pore types, distribution characteristics, and formation stages of the Ordovician paleokarst were analyzed. Then, in attempt to define the origins of porosity development, the formation environments and mechanisms were illustrated. The results of this study showed that pore types of the Ordovician carbonates in the Huai-Fu Basin are mainly composed of intragranular pores, intercrystalline (intergranular) pores, dissolution pores (vugs), fractures, channels, and caves, which are usually in fault and fold zones and paleoweathering crust. Furthermore, five stages and five formation environments of the Ordovician paleokarst were identified. Syngenetic karst, eogenetic karst, and paleoweathering crust karst were all developed in a relatively open near-surface environment, and their formations are mainly related to meteoric water dissolution. Mesogenetic karst was developed in a closed buried environment, and its formation is mainly related to the diagenesis of organic matters and thermochemical sulfate reduction in the Permian-Carboniferous strata. Hydrothermal (water) karst was developed in a deep-buried and high-temperature environment, where hydrothermal fluids (waters) migrated upward through structures such as faults and fractures to dissolve carbonate rocks and simultaneously deposited hydrothermal minerals and calcites. Lastly, a paleokarst evolution model, combined with the related porosity evolution processes, nicely revealed the Ordovician carbonate reservoir development. This study provides insights and guidance for further oil and gas exploration in the Southern North China Basin, and also advances our understanding of the genesis of carbonate paleokarst around the world.

scholarly journals Media corrosiveness and materials resistance at presence of aggressive carbon dioxide

2021 ◽  
Vol 64 (11) ◽  
pp. 793-801
Author(s):  
R. R. Kantyukov ◽  
D. N. Zapevalov ◽  
R. K. Vagapov
Keyword(s):  
Carbon Dioxide ◽  
Oil And Gas ◽  
Gas Production ◽  
Carbon Dioxide Corrosion ◽  
Gas Field ◽  
Hydrocarbon Production ◽  
Field Development ◽  
Wide Range ◽  
Corrosive Effect ◽  
Equipment And Pipelines

At the present stage of gas field development, the products of many mining facilities have increased content of corrosive CO2 . The corrosive effect of CO2 on steel equipment and pipelines is determined by the conditions of its use. CO2 has a potentially wide range of usage at oil and gas facilities for solving technological problems (during production, transportation, storage, etc.). Simulation tests and analysis were carried out to assess the corrosion effect of CO2 on typical steels (carbon, low-alloy and alloyed) used at field facilities. Gas production facilities demonstrate several corrosion formation zones: lower part of the pipe (when moisture accumulates) and top of the pipe (in case of moisture condensation). The authors have analyzed the main factors influencing the intensity of carbon dioxide corrosion processes at hydrocarbon production with CO2 , its storage and use for various technological purposes. The main mechanism for development of carbon dioxide corrosion is presence/condensation of moisture, which triggers the corrosion process, including the formation of local defects (pits, etc.). X-ray diffraction was used for the analysis of corrosion products formed on the steel surface, which can have different protective characteristics depending on the phase state (amorphous or crystalline).

Geological and Field Feasibility Study of Field Development Management Using Marker-Based Production Profiling Surveillance in Horizontal Wells: The Case Study of the Yuzhno-Vyintoiskoye Field

2021 ◽  
Author(s):  
Marat Rafailevich Dulkarnaev ◽  
Yuri Alexeyevich Kotenev ◽  
Shamil Khanifovich Sultanov ◽  
Alexander Viacheslavovich Chibisov ◽  
Daria Yurievna Chudinova ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Oil And Gas ◽  
Water Saturation ◽  
Clay Content ◽  
Horizontal Wells ◽  
Integrated Approach ◽  
Geological Structure ◽  
Gas Field ◽  
Field Development ◽  
Reservoir Rocks

In pursuit of efficient oil and gas field development, including hard-to-recover reserves, the key objective is to develop and provide the rationale for oil recovery improvement recommendations. This paper presents the results of the use of the workflow process for optimized field development at two field clusters of the Yuzhno-Vyintoiskoye field using geological and reservoir modelling and dynamic marker-based flow production surveillance in producing horizontal wells. The target reservoir of the Yuzhno-Vyntoiskoye deposit is represented by a series of wedge-shaped Neocomian sandstones. Sand bodies typically have a complex geological structure, lateral continuity and a complex distribution of reservoir rocks. Reservoir beds are characterised by low thickness and permeability. The pay zone of the section is a highly heterogeneous formation, which is manifested through vertical variability of the lithological type of reservoir rocks, lithological substitutions, and the high clay content of reservoirs. The target reservoir of the Yuzhno-Vyintoiskoye field is marked by an extensive water-oil zone with highly variable water saturation. According to paleogeographic data, the reservoir was formed in shallow marine settings. Sand deposits are represented by regressive cyclites that are typical for the progressing coastal shallow water (Dulkarnaev et al., 2020). Currently, the reservoir is in production increase cycle. That is why an integrated approach is used in this work to provide a further rationale and creation of the starting points of the reservoir pressure maintenance system impact at new drilling fields to improve oil recovery and secure sustainable oil production and the reserve development rate under high uncertainty.

Petrofacies classification using machine learning algorithms

Geophysics ◽  
2020 ◽  
Vol 85 (4) ◽  
pp. WA101-WA113 ◽  
Author(s):  
Adrielle A. Silva ◽  
Mônica W. Tavares ◽  
Abel Carrasquilla ◽  
Roseane Misságia ◽  
Marco Ceia
Keyword(s):  
Machine Learning ◽  
Oil And Gas ◽  
Water Saturation ◽  
Carbonate Reservoir ◽  
Machine Learning Algorithms ◽  
Carbonate Reservoirs ◽  
Training Data ◽  
Southeastern Brazil ◽  
Gradient Boosting ◽  
Data Set

Carbonate reservoirs represent a large portion of the world’s oil and gas reserves, exhibiting specific characteristics that pose complex challenges to the reservoirs’ characterization, production, and management. Therefore, the evaluation of the relationships between the key parameters, such as porosity, permeability, water saturation, and pore size distribution, is a complex task considering only well-log data, due to the geologic heterogeneity. Hence, the petrophysical parameters are the key to assess the original composition and postsedimentological aspects of the carbonate reservoirs. The concept of reservoir petrofacies was proposed as a tool for the characterization and prediction of the reservoir quality as it combines primary textural analysis with laboratory measurements of porosity, permeability, capillary pressure, photomicrograph descriptions, and other techniques, which contributes to understanding the postdiagenetic events. We have adopted a workflow to petrofacies classification of a carbonate reservoir from the Campos Basin in southeastern Brazil, using the following machine learning methods: decision tree, random forest, gradient boosting, K-nearest neighbors, and naïve Bayes. The data set comprised 1477 wireline data from two wells (A3 and A10) that had petrofacies classes already assigned based on core descriptions. It was divided into two subsets, one for training and one for testing the capability of the trained models to assign petrofacies. The supervised-learning models have used labeled training data to learn the relationships between the input measurements and the petrofacies to be assigned. Additionally, we have developed a comparison of the models’ performance using the testing set according to accuracy, precision, recall, and F1-score evaluation metrics. Our approach has proved to be a valuable ally in petrofacies classification, especially for analyzing a well-logging database with no prior petrophysical information.

scholarly journals Dynamics of hydrocarbon production in long-developed fields of the South Caspian basin with emphasis on reserves renewability

2021 ◽  
Vol 11 (3) ◽  
pp. 1081-1091
Author(s):  
A. A. Feyzullayev ◽  
I. Lerche ◽  
I. M. Mamedova ◽  
A. G. Gojayev
Keyword(s):  
Oil And Gas ◽  
Methodological Approach ◽  
Gas Production ◽  
Oil Field ◽  
Gas Condensate ◽  
Caspian Basin ◽  
The South ◽  
South Caspian Basin ◽  
Hydrocarbon Production ◽  
Field Development

AbstractThe scientific basis of the paper is the concept of renewability of oil and gas resources. In accordance with this concept, the purpose of this paper is to estimate the volumetric rate of natural replenishment of the reservoir with oil and gas using the example of long-developed Bibieybat oil and Garadag gas condensate fields in the South Caspian Basin (SCB). The methodological approach of this assessment is based on the authors' assumption that at the late stage of field development, the recoverable amount of hydrocarbon fluids is compensated by the amount of their natural inflow, as a result of which oil or gas production stabilizes. The analysis of the dynamics of hydrocarbon production for the Bibieybat oil field covered the period from 1935 to 2018, and for the Garadag gas condensate field from 1955 to 1979. The rate of natural oil replenishment calculated for 29 operating facilities of the Bibieybat field varies per well within 0.32–1.4 ton/day (averaging 0.76 ton/day) or about 277 ton/year. The rate of natural gas inflow at the Garadag gas condensate field is about 5.2 thousand m3/day per well.

Rock Physics Modelling in Oil and Gas Field Development, A Methodology for Reservoir Characterisation below Shallow Gas

2014 ◽  
Author(s):  
Yusma Bazleigh M Yusoff ◽  
Nor Afiqah Radzi ◽  
Ashraf Khalil ◽  
Amri Amdan ◽  
Chong Weng Hong ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Rock Physics ◽  
Shallow Gas ◽  
Gas Field ◽  
Field Development ◽  
Oil And Gas Field

scholarly journals Seismic expression of miocene carbonate platform and reservoir characterization through geophysical approach: application in central Luconia, offshore Malaysia

2021 ◽  
Vol 11 (4) ◽  
pp. 1533-1544
Author(s):  
Yasir Bashir ◽  
Muhammad Amir Faisal ◽  
Ajay Biswas ◽  
Amir abbas Babasafari ◽  
Syed Haroon Ali ◽  
...  
Keyword(s):  
Seismic Data ◽  
Oil And Gas ◽  
Reservoir Characterization ◽  
Carbonate Platform ◽  
Petroleum Industry ◽  
Seismic Inversion ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Fluid Distribution ◽  
Central Luconia

AbstractA substantial proportion of proven oil and gas reserves of the world is contained in the carbonate reservoir. It is estimated that about 60% of the world’s oil and 40% of gas reserves are confined in carbonate reservoirs. Exploration and development of hydrocarbons in carbonate reservoirs are much more challenging due to poor seismic imaging and reservoir heterogeneity caused by diagenetic changes. Evaluation of carbonate reservoirs has been a high priority for researchers and geoscientists working in the petroleum industry mainly due to the challenges presented by these highly heterogeneous reservoir rocks. It is essential for geoscientists, petrophysicists, and engineers to work together from initial phases of exploration and delineation of the pool through mature stages of production, to extract as much information as possible to produce maximum hydrocarbons from the field for the commercial viability of the project. In the absence of the well-log data, the properties are inferred from the inversion of seismic data alone. In oil and gas exploration and production industries, seismic inversion is proven as a tool for tracing the subsurface reservoir facies and their fluid contents. In this paper, seismic inversion demonstrates the understanding of lithology and includes the full band of frequency in our initial model to incorporate the detailed study about the basin for prospect evaluation. 3D seismic data along with the geological & petrophysical information and electrologs acquired from drilled wells are used for interpretation and inversion of seismic data to understand the reservoir geometry and facies variation including the distribution of intervening tight layers within the Miocene carbonate reservoir in the study area of Central Luconia. The out-come of the seismic post-stack inversion technique shows a better subsurface lithofacies and fluid distribution for delineation and detailed study of the reservoir.

Rock Physics Modelling in Oil and Gas Field Development, A Methodology for Reservoir Characterisation below Shallow Gas

2014 ◽  
Author(s):  
Yusma Bazleigh M Yusoff ◽  
Nor Afiqah Radzi ◽  
Ashraf Khalil ◽  
Amri Amdan ◽  
Chong Weng Hong ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Rock Physics ◽  
Shallow Gas ◽  
Gas Field ◽  
Field Development ◽  
Oil And Gas Field

Geology-Based Reservoir Model Building for Carbonate Reservoirs

2013 ◽  
Author(s):  
Lydia Lagkaditi ◽  
Ashok Srivastava ◽  
Anuj Gupta
Keyword(s):  
Sea Level ◽  
Model Building ◽  
Environmental Influence ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Ct Scanner ◽  
Sea Level Changes ◽  
X Ray ◽  
Reservoir Rocks ◽  
Computed Tomography Scanning

Environment in which carbonate reservoir rocks are deposited was studied by visiting and collecting rock samples from a carbonate reservoir analog located at Jabal Fuwairit in the Northeastern coast of Qatar. The primary objective of this study is to develop methods to characterize carbonate reservoirs. The experimental procedure included collecting samples based on geology, mapping the location and altitudes of the samples using a high-resolution Global Positioning System (GPS) with an altimeter, permeability measurements at selected locations, conducting petrophysical measurements on the samples, Conventional and Micro-X-ray Computed Tomography Scanning (CT Scanning), Scanning Electron Microscopy (SEM), X-ray Energy Dispersive Spectroscopy (EDS) and Atomic Force Microscopy (AFM) imaging. It is observed that the permeability measurements show an alternating pattern as a function of height above sea level. The cyclicity is probably representative of repeating sequences of sea level changes over geological time. CT Scanner and Micro-CT Scanner measurements were employed to obtain vital information about the flow pathways in the rock, thus assisting in calculating the porosity to compare with values measured in the lab. SEM results gave direct visualization of the pore network and information about grain size (500 microns) and intergranular porosity, mineralogy, compared with the EDS results, and lithotype. EDS results showed that reservoir rocks directly exposed to environment had significant alteration due to weathering. However, it is encouraging to learn that samples even few inches away from the surface had minimal environmental influence.

Artificial Neural Network as a Method for Pore Pressure Prediction throughout the Field

2021 ◽  
Author(s):  
Danila Mylnikov ◽  
Viktor Nazdrachev ◽  
Evgeniy Korelskiy ◽  
Yuriy Petrakov ◽  
Alexey Sobolev
Keyword(s):  
Neural Network ◽  
Pore Pressure ◽  
Oil And Gas ◽  
Model Building ◽  
Traditional Approach ◽  
Oil And Gas Industry ◽  
Model Construction ◽  
Analytical Models ◽  
Geomechanical Model ◽  
Field Development

Abstract Geomechanical model construction is an essential part of field development processes planning. Building a correct pore pressure model is one of the key tasks within the process of geomechanical model construction. The traditional approach to pore pressure modeling in oil and gas industry is based on the empirical analytical models usage. This approach has a number of disadvantages, which often lead to the constructed pore pressure model to be incorrect. The authors highlight two most significant disadvantages of the traditional approach: 1) a priori discrepancy between the empirical model and fundamental physical laws; 2) the impossibility of selecting such a combination of parameters of the standard analytical model, for which the resulting pressure corresponds to the entire set of actual field data (pore pressure measurements). This paper proposes a methodology for assessing the pore pressure distribution across the field, based on the usage of neural network technology. This approach potentially eliminates both of the above disadvantages from the pore pressure model building.

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