Fine Geological Model Research Articles

Study on Fine Geological Modeling of Sandstone Reservoir under the Influence of Igneous Rock-A Case of Bohai X Oilfield.

[Purpose] Sandstone reservoirs under the influence of igneous rocks have become some of the most important complex reservoirs. The accurate description of the distribution for this type of reservoir is a major technical problem in hydrocarbon exploration and development. Geological modeling is the fundamental work of reservoir research. However, there is relatively little research on the reservoir modeling of sandstone reservoirs under the influence of igneous rocks. [Method] In this study, taking the Bohai X oilfield as the research object, the distribution characteristics of sandstone reservoirs were characterized, and a quantitative identification method for igneous rocks was established based on seismic, logging, and drilling data. The impact of igneous rocks on sandstone reservoirs was analyzed, and a structural model under a sequence stratigraphic framework was constructed. And then, a three-dimensional geological model of sandstone reservoirs under the influence of igneous rocks was established. [Results] The results show that the physical properties of sandstone reservoirs deteriorate due to the extrusive igneous rocks in the zone with a complex fracture system and the area that volcanic channel developed. After that, referring to the identification and modeling methods of salt domes and using the fine identification and tracking results of volcanic rocks, the volcanic rocks are extracted as attribute bodies, which are finally nested into the geological model. At the same time, according to the influence degree of igneous rocks, a three-dimensional (3D) model was established, which can not only characterize the structure of igneous rocks but also reflect the development of reservoirs. [Conclusions] The research results can better guide the implementation of development wells, avoid reservoir risks, and significantly improve the accuracy of numerical simulation.

Stability analysis of a deep and large open pit based on fine geological modeling and large-scale parallel computing: a case study of Fushun West Open-pit Mine

Accurate input of geological elements is essential for evaluating or predicting natural hazards such as subsidence, landslides, and earthquakes. This paper proposes an approach to carry out an open pit’s overall and whole-process mechanical analysis with complex geological conditions, using precise modeling and large-scale parallel calculation techniques. Taking the Fushun West Open-pit Mine (the largest open-pit coal mine in Asia) as an example, through the elaborate multi-method geological investigation, the interfaces of interbedded shales and mudstones, the unloading zones, and the small structures were identified, a detailed 3D geological model was built and finely meshed in full-size with 100 million degrees of freedom, large-scale parallel numerical simulation was then performed, the results agree well with the InSAR monitoring data and in situ observations. Besides, the simulation can replicate the landslides in recent years. Through the simulation, it is possible to locate the potential landslide area, and targeted backfilling schemes for stability treatment were put forward and further simulated. The results indicate that the proposed approach can more effectively and reliably evaluate the Fushun West Open-pit Mine’s overall slope stability and closure plan.

Wygd Study on prediction method of drilling pressure in low permeability oilfield

During the high water cut development stage of low permeability in M block, the overall recovery degree is low, there has 100 infilling wells been drilled since 2020 to improve the development effect. Before drilling, in order to avoid the risk of pressure safety, it is necessary to shut down the peripheral water injection wells to relieve the pressure, at the same time.Since the M Block reservoir is a low permeability reservoir, the pressure relief time after drilling off is long, which increases the impact on the production of developing wells and increases the fluid transportation and the related production costs, while there is no uniform standard for the time, pressure and distance of drilling off. In order to control the production loss of developing wells and save the shut-in cost. This paper applies numerical simulation and reservoir engineering method, by establishing fine geological model, optimizing simulation technology, considering the influence of start-up pressure gradient, establishing theoretical formula and mathematical model of drilling pressure, clarifying the law of drilling-off pressure relief and pressure drop, calculating the formation pressure of single well in the whole area, forming the drilling-off limit and rapid pressure prediction method, through comparison and verification, the overall deviation is 3.8%, and the method is accurate and reliable.

Numerical Simulation of Two-Phase Flow in Glutenite Reservoirs for Optimized Deployment in Horizontal Wells

It is known that the pore media characteristics of glutenite reservoirs are different from those of conventional sandstone reservoirs. Low reservoir permeability and naturally developed microfractures make water injection in this kind of reservoir very difficult. In this study, new exploitation methods are explored. Using a real glutenite reservoir as a basis, a three-dimensional fine geological model is elaborated. Then, combining the model with reservoir performance information, and through a historical fitting analysis, the saturation abundance distribution of remaining oil in the reservoir is determined. It is shown that, using this information, predictions can be made about whether the considered reservoir is suitable for horizontal well fracturing or not. The direction, well length, well spacing and productivity of horizontal well are also obtained.

Fine Geological Modeling of Complex Fault Block Reservoir Based on Deep Learning

Nowadays, people’s demand for underground mineral resources is increasing, and geological disasters have occurred frequently in recent years. Geological disasters refer to geological effects or geological phenomena that are formed under the action of natural or man-made factors, causing loss of human life and property, and damage to the environment; such as landslides, collapses, mudslides, and ground subsidence. Under such a background, people must accelerate the exploration of complex geological structures. This paper is aimed at using the methods and concepts of deep reinforcement learning. Deep learning is to learn the inherent laws and representation levels of sample data. The information obtained during these learning processes is of great help to the interpretation of data such as text and images. In this way, the fine geology of complex fault-block reservoirs is modeled and studied. Geological structures and phenomena are discussed through convolutional neural network models and computer techniques. At the same time, the multitask bird recognition network is used to extract and classify geological images, so as to construct geological model maps with different spatial structures. Finally, the quality of the fault reconstruction model, the calculation of reservoir geological simulation reserves, and the evaluation of the water injection development effect of complex fault blocks are analyzed. In the evaluation of the development effect of water injection in complex fault blocks, comparing the relationship curve between the actual comprehensive water content and the oil recovery factor with the standard curve, the comprehensive water content of the initial block increased rapidly. Through timely and dynamic water allocation and comprehensive management, the water cut rising speed is controlled. The current comprehensive water cut of the reservoir is between 60% and 80%, the actual curve is between 25% and 35%, and the estimated waterflooding recovery is about 30%.

A study on modeling a deep sand geothermal field in South China

It is crucial for financial providers, investment groups, resource developers and exploration companies to rate a new geothermal project in the respect of resource and reserve. The existing volumetric method is generally constrained by limited information when projects at the early stage of development. The objective of this study is to estimate the potential of a geothermal field by a refined geological model and 3D numerical temperature model. We establish a fine geological model of a geothermal field in South China and thereby calculate the conductive 3D numerical temperature model. Based on a comprehensive analysis and interpretation of borehole measured data and well-log data, the regional variation and spatial distribution of thermal and petrophysical properties are both incorporated in the geological model. The results show that the Neogene and Quaternary strata in the study area have an average porosity of 36% and an average rock thermal conductivity of 3.15 W (m K)−1, the Weizhou Formation have an average porosity of 29% and an average rock thermal conductivity of 2.54 W (m K)−1, the Liushagang Formation have an average porosity of 22 % and an average thermal conductivity of 2.21 W (m K)−1, the Changliu Formation have an average porosity of 13% and an average thermal conductivity of 2.75 W (m K)−1. Based on the fine geothermal geological model, the heat is assumed to be driven by conduction, and the results show that the bottom temperature of the Weizhou Formation in the hydrothermal sandstone reservoir is 96-168 degrees Celsius, and the high temperature area is concentrated near the down-thrown side of the fault, indicating that the geothermal resources are favorable area and the geothermal energy is 7.89 × 1014 J.

Study on reservoir description technology of complex fault block oilfield——Taking the South 1st member of D sag as an example

The D sag has developed faults, serious erosion and fault loss, developed glutamate, strong heterogeneity, and large formation dip, which makes stratigraphic comparison difficult and unclear understanding of oil reservoir and oil-water relationship during the development process. For this reason, this study was carried out. On the basis of the existing seismic interpretation results, carry out the fine structural interpretation of the main sub-layers in the study area; carry out the study of sedimentary characteristics, divide the sedimentary facies, and clarify the sedimentary characteristics of the main sand bodies; use the core analysis data to establish the interpretation of physical parameters in the study area model, and establish a fine three-dimensional geological model, through the study of oil-water distribution law, carry out potential research, and select favorable well-distributed blocks.

Application of multivariate linear methods to the development of a stratified system in Block II of Area A

This study is a numerical simulation study of different stratigraphic development schemes for three encrypted well networks based on historical fitting by establishing a fine geological model for Block II of Area A. The relationship between reservoir physical parameters and recovery rates for different stratigraphic combinations is obtained by applying multiple linearity regression methods to guide the delineation of stratigraphic development sections in multi-layered non-homogeneous reservoirs.

Evaluation on the dynamic sealing capacity of underground gas storages rebuilt from gas reservoirs: A case study of Xinjiang H underground gas storage

In order to provide effective guidance for optimizing and adjusting the maximum operation pressure and dynamic monitoring well pattern of underground gas storages (hereinafter referred as gas storages) and ensure the operation safety of gas storages, this paper takes Xinjiang H gas storage whose storage capacity and peak shaving capacity are the highest in China as the research object to establish a 3D fine geological model and a 3D dynamic geomechanical model in the regional scale of H gas storage based on the alternating change characteristics of geostress field during the high-speed cyclic injection and production of gas storage, combined with the geological, seismic, logging and various laboratory core experiment results. Then, the trap dynamic sealing capacity of H gas storage under the action of alternating stress after 14 years of depletion development of its original gas reservoir and long-term high-speed injection and production after its reconstruction from the gas reservoir was evaluated comprehensively. And the following research results were obtained. First, the change of the formation pressure in H gas storage has a significant effect on the regional geostress field. Second, after the development of the original H gas reservoir, the geostress on the two sides of the fault are greatly different, but the cap rock is not deformed and failed and the reservoir controlling fault as the gas bearing boundary doesn't glide, which ensures the safety of reconstructing H gas reservoir into gas storage. Third, due to the high-speed injection and production of H gas storage, the geostress field becomes more uneven, which has a potential negative impact on the integrity of the injection and production wells of the gas storage. Fourth, during the long-term high-speed injection and production operation of H gas reservoir, the cap rock does not undergo shear and tensile failure, but the numerical simulation of geomechanics shows that the long-term high-speed injection and production of the gas storage results in the relative sliding deformation (maximum about 5 cm) on both sides of H fault in the south of the reservoir, so the sealing capacity of H fault is a weak point impacting the integrity of the gas storage. Fifth, it is recommended to deploy monitoring wells at the upper block of H fault in the south of the gas storage to strengthen the injection and production dynamic monitoring. In conclusion, this study performs a qualitative and quantitative evaluation on the trap dynamic sealing capacity of gas storages rebuilt from gas reservoirs under the action of alternating stress, and it plays an important guiding role in ensuring the long-term injection and production safety of H gas storage.

Orderly distribution and differential enrichment of hydrocarbon in oil-rich sags: A case study of Dongying Sag, Jiyang Depression, Bohai Bay Basin, East China

Based on fine geological modeling and taking the evolution of key reservoir-forming elements as the main line, the mechanism of orderly distribution and differential enrichment of hydrocarbon was revealed by studying the joint evolution and coupling effect of pressure, fluid and reservoir properties. Orderly development of sedimentary systems in a rift basin is the base of orderly distribution of reservoirs, and the continuity of pressure structure is the key to controlling orderly distribution of reservoir. From the sag center to the margin, in the sag, second-order sequence and large-scale sedimentary system, the reservoirs appear in an orderly distribution from lithologic reservoir to structural reservoir to stratigraphic reservoir. Alternative acid and alkaline actions controlled the development of high quality reservoirs in the mid-fan sandy conglomerate bodies in the steep slope, resulting in the oil and gas accumulation pattern of sealing at the root fan and enrichment at the mid-fan, in which the breakthrough pressure difference between root fan and mid-fan determines the reservoir enrichment level. The action of acidic fluid controlled the development of high quality reservoirs in beach bar sand and turbidite. The pressure difference between high-pressure source rock caused by pressurization of hydrocarbon generation and low-pressure reservoir caused by reservoir improvement provided driving force for oil and gas charging, giving rise to the pressing-absorbing oil and gas charging mechanism controlled by source rock overpressure. The research results have guidance and reference significance for fine exploration in mature exploration areas.

3D paleotectonic stress field simulations and fracture prediction for marine-continental transitional facies forming a tight-sandstone reservoir in a highly deformed area

Marine-continental transitional facies coal measures that form tight sandstone reservoirs in heavily deformed areas are a new field for natural gas exploration. The degree of fracture development is the core factor in the enrichment of the potential natural gas resources. In this paper, using the Shanxi Formation in southern Qinshui Basin of eastern China as an example, the characteristics of fracture development in tight sandstone reservoirs were studied, and the paleotectonic stress field was reconstructed. On this basis, the fracture development of the area was predicted. The results show that fractures of different scales were developed in the tight sandstone of the Shanxi Formation and that over 90% of these fractures are tectonic. The types of fracture filling in the tight sandstone of the Shanxi Formation are mainly unfilled and half-filled. Fine geological modeling and paleostress simulations were conducted on the II sand group of the Shanxi Formation using the 3D finite element method. The geostress field of the target layer in the Himalayan period was restored. Considering that the tensile and shear fractures of the target layer were both well developed, we constructed a comprehensive rupture rate (IF) to quantitatively predict the level of development of the fractures by combining the Griffith tensile failure criterion and Mohr–Coulomb shear failure criterion. The prediction results are in agreement with the actual geological conditions, which indicates that this method is suitable for characterizing the fractures in marine-continental transitional facies coal measures that form tight sandstone reservoirs in heavily deformed areas.

The reasonable development technology policy in sweet spot of tight gas reservoir

The development of sweet spot in tight gas reservoir is restricted by various factors, which cannot guarantee reasonable, efficient, and low-cost development, and technical policy of development is also immature. Through fine geological modeling and numerical simulation technology, and in accordance with the microseismic monitoring results, the pressure recovery test data, and analysis of the relationship between irreducible water saturation and permeability, history matching is conducted. On this basis, new wells can be designed and simulated again in this sweet spot. Finally, it is concluded that the horizontal well with staggered well pattern is the reasonable development of sweet spot, the reasonable well space is 600–800 m, the reasonable length of the horizontal section is 1200 m, and the reasonable initial gas production rate is 8 × 104 m3/day.

Establishment of Geological Knowledge Database for Meandering River Reservoirs in Offshore Oilfields With Large Well Spacing

Based on quantitative logging microfacies identification, seismic constraint facies map compilation and horizontal wells architecture analysis, the reservoir geologic knowledge database of different grades configuration unit was established for meandering river reservoirs of Lower Minghuazhen Formation in Q oilfield. The results show that the average point bar sand body width is 360-783 m, the average sand body thickness is 4.0-8.5 m, the ratio of width to thickness mainly distributed in 40-100. Average lateral accretion layers dip is 5.7°, lateral accretion layers horizontal interval mainly distributed in 70-200 m. On the basis of reservoir geological knowledge database, a fine geological model was established together with sequential indicator method and equivalent characterization method. Base on the reservoir geologic knowledge database and geological modeling results, 130 adjustment wells were successfully deployed and implemented at the comprehensive adjustment process of Q oilfield, these wells made an obvious oil production increase effect.

A method of production profile quick prediction based on typical curves: A case study of the Upper Shale large multi-layered sandstone reservoir, Rumaila Oilfield, Iraq

Abstract Combined the advantage of reservoir simulation and conventional reservoir engineering methods, the paper proposes a quick method for production performance prediction, which is based on type curves generated from reservoir simulations of sector model. Fine reservoir simulation is conducted based on the fine geological sector model of the large sandstone reservoir, and type curves of different reservoir type under different development options are generated. Then based on results of reservoir type classification for all layers, well productivity and injectivity evaluation, production profile of the whole field can be predicted. This new method can reflect the impact of reservoir heterogeneity and development option change on reservoir performance. Take a large multi-layered sandstone reservoir Upper Shale reservoir in Rumaila Oilfield for example to illustrate the workflow. The comparison between results of fine reservoir simulation and that of the new method validate reliability of the new method, and the new method consume much shorter time.

Numerical Simulation Study on the Technology of Different Nature Polymer Injection in Thin and Bad ReservoirNumerical Simulation Study on the Technology of Different Nature Polymer Injection in Thin and Bad Reservoir

The thin and poor reservoir , as an important replacement of production decline in the later stage of oilfield development, is gradually becoming the target of three oil recovery due to the large proportion of its reserves. For Class Ⅲ and Class Ⅳ of thin and poor reservoirs with large contradiction between the layers, if the same molecular weight polymer flooding is used to drive oil, it is easy to affect the development effect because of low producing degree of poorly matched reservoir. On the basis of the fine geological model, the water cut and cumulative oil production of the simulated area were fitted by the simulation software of eclipse, and the development effect of different production schemes is analyzed and forecasted. Research results show that the effect of different layer different nature polymer injection is better than that of general polymer injection, and the effect of different stage different nature polymer injection is better than that of the different layer different nature.

Anisotropic grid generation for dynamic simulation in heterogeneous hydrocarbon reservoirs

Coarsening from fine geological model to coarse dynamic model is one of the main practical stages in reservoir simulation process in order to minimize simulation run time. In order to preserve accuracy and minimize simulation run time simultaneously, non-uniform element distribution is required to capture dynamic interest and high-flow regions in heterogeneous porous media. In this paper, an automatic coarsening method has been developed to generate anisotropic unstructured mesh with high aspect ratio elements to minimize total number of elements in dynamic model. A high resolution indicator which is called Metric Indicator is generated based on permeability and well effect parameters. Metric Indicator guides the mesh generator to create elements with the desired size, shape and orientation. Single phase gas flow and two-phase gas-water flow equations in a heterogeneous porous media have been solved using Control Volume Finite Approximation (CVFA) method. The comparison between the simulation results of the proposed method in this study and fine-grid model as a reference model demonstrates that the presented method can obtain high accuracy results with the minimum number of elements and the minimum simulation run time.

Fine Geological Modeling of the Tight Oil Reservoir

Fine Geological Modeling of the Tight Oil Reservoir

A novel approach for automatic grid generation for multi-phase flow simulators: A robust computational framework for mass transfer at bubble point pressure

Abstract Coarsening from fine geological model to dynamic coarse scale is an essential task in reservoir simulation. In this paper a new approach is introduced to create a coarse dynamic model based on effective parameters of fluid flow in porous media. In this technique, the effects of fine scale permeability map, key flow paths (streamlines) and well location are considered to build a coarse dynamic model from a fine geological one. An exact element size map is generated by comparing all the mentioned effective parameters and making the element size indicator by selecting the maximum value. This element size map (background grid) is applied to build an unstructured mesh for discretization of the reservoir. Afterward, this intelligent mesh generator was employed in three-phase flow simulation. Moreover, a novel computational framework is developed for the evaluation of bubble point pressure to prevent divergence of the solution when the reservoir conditions change. To evaluate the performance of the developed model, the fluid flow rate obtained by this model is compared to that obtained by the uniform grid model. It is found that the proposed method provides more accurate results for fluid flow rate compared to the uniform grid model. Moreover, it is faster and computationally less expensive than the fine model. This model can be applied in reservoir simulators and provides more accurate and reliable results in less CPU time compared to the traditional mesh generation techniques. In addition, the proposed model solves the problem of divergence of the solution at the bubble point pressure.

About the Use of Quality Indicators to Reduce Information Loss When Performing Upscaling

Hydrocarbon reservoirs are characterized by the spatial distributions of petrophysical properties. These spatial characteristics are usually derived from well data and seismic information. To study a reservoir, the engineers build a fine geological model, also called a geostatistical model, to represent the field. The purpose is to capture as well as possible the peculiarities and heterogeneity of the true reservoir. At this stage, performing a flow simulation with such detailed geological models is just too time-demanding. Therefore, a possibility consists of upscaling the geological model to an upscaled mesh, thus resulting in a coarse reservoir model for which fluid flow can be numerically simulated in a reasonable amount of time. The coarse grid blocks of this reservoir model are attributed equivalent petrophysical properties related to the properties populating the fine grid blocks. These properties are upscaled, and so they do not capture all of the details of the fine model. In this paper, we investigate the potential of various numerical and easy to compute criteria, which help evaluate the information loss due to the upscaling process. Our final purpose is to provide and access the reliability of quality indicators, which make it possible to evaluate the quality of the upscaled reservoir model. The potential of this systematic and integrated study is illustrated with two types of numerical experiments based upon the SPE10 case. First, we apply different upscaling methods to determine coarse reservoir models. Quality indicators are computed for each of them so that we identify the most suitable upscaling methods. Then, the upscaled models are input to flow simulators to check the accuracy of our quality estimations. Second, we also investigate the influence of coarsening and try to determine from the computed quality indicators the coarse cell size above which too much information is lost.

Application of Three-Dimensional Fine Geological Modeling in Complex Fault-Block Reservoir with Low Permeability

Three dimensional geologic modeling is a powerful tool for reservoir development stages of geological study, it can solves many traditional problems existing in geological research through the establishment of precise three dimensional geologic modeling and represents an important direction for the further development of oilfield geological research. Low permeability and thin interbed reservoir of complex fault block have the characteristics of severe heterogeneity, complex relations of oil-water distribution, poor development effect, it is necessary to built high precision three dimensional geologic modeling in the process of oilfield exploration and to fine reservoir description and prediction on this basis, finally reach the purpose of reduce the risk of development and improve the economic benefit. This paper makes geological modeling research and builds structural models sedimentary micro-facies models and phased property model for Zhuzhuang block of Jiangsu oilfield by utilizing three dimensional geologic modeling technique and petrel geology modeling software on the basis of integrated using of geology, logging, oil production test, production of dynamic information, thus it provide a solid basis for reservoir's development and adjustment.