| Publisher: Society of Exploration Geophysicists
| ||||||||
Similar Journals
|
Interpretation
Number of Followers: 1  Hybrid journal (It can contain Open Access articles)ISSN (Print) 2324-8858 - ISSN (Online) 2324-8866 Published by Society of Exploration Geophysicists  [3 journals]
|
- Introduction to special section: Understanding and modeling the
architecture of conventional and unconventional hydrocarbon reservoirs-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
PubDate: Tue, 14 Feb 2023 00:00:00 GMT
-
- Hidden hydrosphere under the Caspian Sea: Geophysical evidence and
sea-level influence-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: We analyzed geologic-geophysical data, both from archives and collections in recent expeditions by the Shirshov Institute of Oceanology of Russian Academy of Sciences, and revealed many anomalies in the seismoacoustic wavefield. Anomalies are of two types: horizontal disturbed layers and vertical pipes. Anomalies form associations — pipes (chimneys) are rooted in disturbed layers and go through sediments up to the seafloor and form pockmarks. We consider all specified seismic anomalies and bottom microrelief as a possibility of vertical migration of gas and water via sediments (fluid from sediments to water and from seawater to sediments). It is expected that the fluids form a huge underground hydrosphere below the Caspian Sea. To test the fluid flow, we made a mathematical model of fluid discharge and absorption in bottom sediments. We hypothesize that the Caspian Sea level fluctuates, at least partially, due to cycles of the submarine ground water discharge and sea water absorption back into the sediments. This cyclicity of fluid discharge and absorption correlates with regional seismic events. The earthquakes cause tectonic relaxation, triggering the absorption process, and sea-level drop due to reverse flow into sediments. In other periods, the tectonic tension causes sediment compression and fluid discharge to sea water, which causes sea-level rise. The model was tested on the recent (past 100 years) sea-level change curve. As a result, we got a distribution of the general volume of fluid flows depending on the infiltration coefficient. The real change in the Caspian Sea volume is at the lower range of the calculated values, so we cannot neglect the effect of “gas pipes” (“chimneys”) on the Caspian Sea-level change.
PubDate: Mon, 13 Feb 2023 00:00:00 GMT
-
- Signal processing methods for crosswell electromagnetic imaging system
-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The principle of crosswell electromagnetic (EM) imaging is similar to that of induction logging. The difference between them is that conventional induction logging can only measure the formation conductivity within a few meters around the well. However, crosswell EM imaging can be used in two wells with a separation distance of up to 1000 m. Several novel signal processing methods for crosswell EM imaging systems are developed for calibration, casing correction, and hybrid Jacobian matrix calculation. To conveniently perform calibration on the ground, the EM field formula in a vertical layered media is derived based on Maxwell equations, and the relationships between the received signal and frequency, formation conductivity, and transceiver spacing are subsequently derived. Furthermore, a new calibration method is developed. The EM field formula for a radial layered media is derived, and the analytical expressions describing the relationship between the receiving signal and borehole parameters, metal casing parameters, formation parameters, and receiver location are obtained. The effects of mud resistivity, metal casing position, metal casing resistivity, permeability, cement ring resistivity, transmitting frequency, and receiver location on the crosswell EM receiving signal are simulated. It is determined that only the casing required a correction. The influence of the metal casing is corrected by establishing a database. The difference between the corrected data and data obtained without a metal casing is less than 1%. There is a large error in the calculation of the Jacobian matrix in some regions when Green’s function was used. A hybrid Jacobian matrix calculation method combining local perturbation and a global Green’s function is developed, which significantly reduced the error and improved the inversion accuracy.
PubDate: Thu, 02 Feb 2023 00:00:00 GMT
-
- In appreciation of reviewers and editors
-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
PubDate: Wed, 01 Feb 2023 00:00:00 GMT
-
- Contrasting faulting styles of salt domes and volcanoes: Can unsupervised
learning techniques differentiate fault styles'-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: An attractive feature seen on seismic data, also known as funny-looking thing (FLT), has a wide range of interpretations, from noise patterns to amplitude anomalies. An example of an FLT is the similar faulting patterns between a volcanic intrusion and a salt intrusion from the point of view of a machine learning (ML) algorithm. Oftentimes, seismic interpreters do not have a complete data set or geologic background to determine the genesis of the observed features. This can be particularly perplexing when trying to determine if an intrusion is volcanic or halokinetic in origin because they exhibit similar geomorphologies. Examining the differences in these features in the Gulf of Mexico, a well-documented salt basin, and the Taranaki Basin in New Zealand, which is igneous prone, can help to understand the differences. The analysis aims to discern geologic features based on the geometries and attributes shared by seismic data and remote sensing tools. Seismic attributes and ML techniques highlight differences and similarities between the intrusions, including the discussion of using ML techniques, such as self-organized maps (SOMs), an unsupervised ML technique, and cluster fault systems, without regard to the geologic context. The attributes used in the SOM are fault probability, fault dip azimuth, fault dip magnitude, and thin-bed detector. Fault probability is performed through a combination of convolutional neural network fault prediction and a skeletonization process. Once the faults are clustered using SOM, the visualization of fault architecture due to the existing mount (either volcano or salt dome) is done considering high fault probabilities (>75%). The methodology consists of selecting the neurons from the SOM grid corresponding to the presence of faults and combining them with fault probability and a fault dip azimuth using a crossplot. The crossplot product assists in the automatic extraction of the fault planes using: (1) a voxel representation of the fault planes and (2) fault patches representing the fault planes. Moreover, the visualization technique defined demonstrates that the crossplot product yields better-defined fault planes. With the fault system characterized, compared horizon slices using coherence, fault dip magnitude, and azimuth against remote sensing images with similar attributes. In conclusion, our methodology combines technologies to differentiate the genesis of intrusion — salt or igneous — using the fault presence and could be helpful in frontier exploration or planetary exploration.Geologic feature:Comparison of extensional faults due to salt and igneous intrusionsSeismic appearance:In the symmetric salt dome, crown faulting style with a set of synthetic and antithetic faults around the salt dome; for the igneous systems, symmetric radial faultsFormation:Upper and Lower Wilcox (Gulf of Mexico); Ariki Formation — Mo hakatino Formation (Taranaki)Age:Upper Miocene and Lower Pliocene (Gulf of Mexico); Mid Pliocene (Taranaki)Location:Offshore Gulf of Mexico and Offshore Northeast New ZealandSeismic data:From the Gulf of Mexico: B-78-89-LA-3D, B-69-94-LA-3D, B-54d-94-LA-3D, and B-69a-94-LA-3D. From New Zealand: Nimitz and Kora 3DAnalysis tools:Structural-oriented filter, Sobel similarity, fault dip magnitude and azimuth, CNN automatic fault prediction, and SOM classification
PubDate: Fri, 27 Jan 2023 00:00:00 GMT
-
- Hydrocarbon generation and expulsion of the Fengcheng Formation in the
Mahu sag, Junggar Basin, China: Implications for shale oil resource
potential-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The Permian source rocks in the Junggar Basin are widely developed, especially the Fengcheng Formation, which is the most significant source rock in the basin. However, due to insufficient research on the hydrocarbon generation (HG) and hydrocarbon expulsion (HE) characteristics of the source rocks, it is unclear whether a significant amount of retained hydrocarbons remain within shales. In general, the original organic matter abundance and kerogen type control hydrocarbon generation potential (HGP) and HE capacity in lacustrine shales. Therefore, the degradation rate method was used to establish the original organic carbon recovery model for different types of kerogen. Combined with the geologic and geochemical characteristics of the source rock, the HG, HE, and shale oil resource potential of the Fengcheng shale have been evaluated. We have found that the Fengcheng shale is mainly carbonate-type mudstone widely distributed with an average thickness greater than 100 m. The Fengcheng shale is composed of type II kerogen and reached the mature to high-mature thermal maturity stage, with the maximum original organic carbon exceeding 4.0 wt%. Meanwhile, the amount of retained hydrocarbons within shales is abundant according to the HGP model. Monte Carlo simulation finds that the shale oil resources of the Fengcheng shale are 23.30 × 108 t. Free oil resources account for 60%, reaching 13.75 × 108 t, indicating tremendous shale oil exploration potential.
PubDate: Fri, 27 Jan 2023 00:00:00 GMT
-
- Why high porosity but low-production wells occur in carbonate reservoirs:
An explanation from the perspective of pore structure-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: High porosity but low-production wells exist in the Leikoupo Formation in the Sichuan Basin, China. The unclear explanation for this phenomenon has led to the failure of fracture development. We selected 15 cores from the study area based on the oil test data to investigate the cause from the pore structure perspective. The pore structures were studied via a variety of petrophysical experiments, which include conventional physical property analysis, casting thin section, nuclear magnetic resonance technique, and constant-rate mercury injection. The results indicate that the main explanation for the high porosity but low-production wells is that the larger pore-to-throat ratio makes for poor pore connectivity and more large pores and vugs are trapped. Movable fluid saturation can be significantly influenced by microscopic pore structure rather than physical parameters, which is positively affected by throat radius and negatively correlated with the pore-throat radius ratio, relative sorting coefficient, and tortuosity of the throat. The results provide a basis for the exploration of carbonate reservoirs from a microscopic perspective.
PubDate: Fri, 27 Jan 2023 00:00:00 GMT
-
- Well trajectory optimization of ultradeep and high-pressure drilling
engineering based on high in situ stress as the main control factor: A
case study from the Ordovician carbonate reservoir in the Shunbei area of
the Tarim Basin-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: With increasing oil and gas exploration and development, well trajectory optimization has gradually become the focus of the oil and gas industry. Considering the wellbore instability in the Shunbei area of the Tarim Basin, the well trajectory was scientifically optimized under the guidance of rock mechanics, drilling engineering, and mathematical methods, combined with actual geologic data, and with in situ stress as the main controlling factor. In this paper, the stress state of the wellbore is analyzed by linear elastic theory to establish the stress distribution model of the wellbore. The safety window model of wellbore stability is established using different rock failure criteria to calculate the collapse pressure and fracture pressure of the formation. Based on this, the safe mud density window is defined to achieve wellbore trajectory optimization. Finally, the influence factors of wellbore stability are discussed, and the applicability of different rock failure criteria is evaluated. The results indicate that under the normal faulting stress regime condition in the study area, the direction of horizontal minimum principal stress is the best drilling direction, where the borehole inclination angle of α > 50° is the optimal well trajectory. The wellbore stabilities of high-angle deviated wells and horizontal wells are better than those of low-angle deviated wells and vertical wells. The calculation results of the Mogi-Coulomb criterion can describe the conditions of the in situ stress field more accurately. The safe windows for different well trajectories are obtained directly by the numerical method, which is very practical for optimizing well trajectories and improving wellbore stability.
PubDate: Tue, 24 Jan 2023 00:00:00 GMT
-
- An improved seismic fluid identification method incorporating squirt flow
and frequency-dependent fluid-solid inversion-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Joint inversion of seismic amplitude and frequency information for fluid discrimination works as a popular approach for reservoir fluid identification. However, ignorance of the factor caused by fluid flow and the viscosity of oil and gas in current frequency-dependent inversion approaches leads to the inaccuracy of oil and gas prediction. Therefore, based on squirt flow and viscoelastic theory, a new frequency-dependent viscoelastic squirt-flow fluid factor is established, which is compared with other conventional fluid factors to verify its advantages in fluid detection. In addition, a new linearized reflectivity equation related to frequency-dependent viscoelastic squirt-flow fluid factor is derived. Finally, to verify the feasibility of the new fluid factor in predicting oil/gas, a frequency-dependent elastic impedance inversion method is introduced. Synthetic data and field data examples find that frequency-dependent viscoelastic squirt-flow fluid factor can eliminate the interference of “false bright spots” in conventional fluid factors inversion and has a higher vertical resolution, which demonstrated the effectiveness and stability of our method in fluid prediction.
PubDate: Mon, 09 Jan 2023 00:00:00 GMT
-
- Identification of flow units using the gas flow experiments and static
data in heterogeneous oolitic reservoirs of the Puguang gas field-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Identification of flow units in heterogeneous carbonate reservoirs is challengeable. The core wells, thin section, physical property measurements, and logging data from Feixianguan (Triassic) oolitic reservoirs of the Puguang gas field are studied in detail. Three pore types are identified: intergranular pore (Inter-P), intergranular and intragranular pore (Inter-Intra-P), and intragranular pore (Intra-P). There is a discrete correlation between porosity and permeability, but a relatively good linear relationship between Inter-P and Inter-Intra-P pore types. Combining the method with flow experiments, a new method for flow unit identification based on the flow experiments under simulated reservoir conditions is developed. The flow capability index (FCI) obtained from flow experiments can directly reflect the varieties of gas flow behavior in different reservoirs and can distinguish flow unit types. From the experiment results of 20 cylinder samples, similar FCI values are considered to be the same flow unit; meanwhile, the FCI, reservoir quality index (RQI), and permeability thresholds are obtained from related crossplots, thereby dividing four types of flow units and their thresholds. The RQI prediction formula is established by interpreting the measured physical property data and related logging data in Inter-P and Inter-Intra-P. The flow unit identification of coring well using predicted RQI and measured RQI is close to the observed results, especially in FU1 and FU3. This finds that the combination of the gas flow experiments and static data can effectively support flow unit identification and reservoir division in the Puguang gas field.
PubDate: Fri, 06 Jan 2023 00:00:00 GMT
-
- The microdistribution of fluid and its effect on pore structure in shale:
A case study of lacustrine Chang 7 shale, Ordos Basin-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The pore fluid distribution in nanosized pores in shale cannot be observed directly with the current observation equipment which makes it difficult to study the fluid behavior in the shale pore system. To better understand pore fluid evolution and distribution in shale and its effect on pore structure with increasing maturity from immature to oil windows, a serial of samples with different maturity have been collected from the Lower Triassic lacustrine clay-rich Chang 7 shale in the Ordos Basin and treated with oven drying and sequential extraction to remove water, mobile oil, and asphaltene. We have measured the pore-size distributions in the presence of different pore fluids by using the mercury intrusion and N2 adsorption and desorption testing. The results indicate that (1) the pores in the clay-rich samples are mostly slit-shaped mineral pores, consist of a small number of macropores (pore size >50 nm) and a large number of mesopores (pore sizes between 7 and 36 nm), and also including a small amount of poorly developed organic matter-hosted pores. (2) Different types of pore fluids appear to occupy different pore-size ranges. Water prefers to occupy the mineral mesopores. Mobile oil (extracted by n-hexane) is mostly distributed in 2–10 nm-sized organic-matter-hosted mesopores. Asphaltenes are mostly distributed in mesopores in the range of 25–36 nm. (3) The presence of pore fluid significantly impacts the pore structures of shale. The pore volume and specific surface area decrease due to pore fluid occupation, even for low-maturity samples in which the organic matter pores also are developed but cannot be observed under a scanning electron microscope. (4) Organic matter abundance and thermal maturity have significant effects on the pore fluid composition and distribution. With increasing maturity, water is gradually displaced by oil due to hydrocarbon generation and accumulation in large mineral pores.
PubDate: Fri, 06 Jan 2023 00:00:00 GMT
-
- A deep learning framework for seismic facies classification
-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: We have proposed a deep neural network-based framework for seismic facies classification. We implement two different neural networks based on the architectures of DeepLabv3+ and generative adversarial network for segmentation and compare the mapping results from seismic reflection data to lithologic facies. DeepLabv3+ predictions have sharper boundaries between the predicted facies whereas generative adversarial network output has a better continuity of predicted facies. We incorporate uncertainty analysis into the workflow using a Bayesian framework. The proposed approach consisting of joint analysis of predicted facies from multiple networks along with uncertainty in prediction accelerates the interpretation process by reducing the need for human intervention and also lessens individual biases that an interpreter may bring. We determine the effectiveness of the proposed algorithm by testing on field data examples, and we find that the proposed workflow classifies facies accurately. This may potentially enable the development of depositional environment maps in areas of low well density.
PubDate: Fri, 06 Jan 2023 00:00:00 GMT
-
- Well-logging evaluation of the shale gas potential in the lower Silurian
Longmaxi Formation, Weiyuan, southern Sichuan Basin, China-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Recent observations of shale gas breakthroughs in the Weiyuan marine shale gas play in the Sichuan Basin have attracted great interest. To better understand these breakthroughs, we have used core description, cyro-focused ion beam scanning electron microscopy data, X-ray diffraction data, organic geochemistry, and well-logging data to better understand the reservoir characteristics carbonaceous shale, calcareous shale, and siliceous shale lithology, with a focus on organic-rich shale units. We find that conventional well-log methods are effective in mapping the spatial distribution of organic-rich shale in the Weiyuan area where the total organic carbon (TOC) content in the Longmaxi Formation ranges from 1.35% to 6.95%, averaging 4.42%. The kerogen is type I-II, and the vitrinite reflectance (Ro) is greater than 2.57%, which indicates that the formation is susceptible to shale gas accumulation. The clay mineral content ranges from 48 to 63 wt% (avg. 51 wt%) with illite and chlorite averaging 73.8% and 25.7%, respectively. The brittle mineral quartz and plagioclase content ranges from 32 to 61 wt% (avg. 47 wt%). Compared to the surrounding lithologic units, the marine shale exhibits relatively high gamma ray, neutron, sonic, resistivity, potassium, and uranium (U) values and relatively low density, photoelectric effect, and thorium/U values, allowing us to construct crossplots to define the units of interest. Using the same process, we quantify the TOC content providing a spatial distribution of organic-rich shale using conventional well logging.
PubDate: Wed, 28 Dec 2022 00:00:00 GMT
-
- Study on the pore structure and fractal characteristics on shale rock and
isolated organic matter in lacustrine shales from the Changling fault
depression in the Songliao Basin, China-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The stock of shale gas in the Shahezi shale reservoir in the Changling fault depression, Songliao Basin, is believed to be worth exploring. In-depth study on the pore structure and fractal characterization of organic matter (OM) can help better understand the pore system of shale reservoir, which has implications for the exploration of lacustrine shale. To demonstrate the nanoscale pore structure and irregularity of the isolated OM, we collected a large number of samples and then conducted a series of laboratory experiments, such as X-ray diffraction, scanning electron microscopy, and CO2 and N2 adsorption experiments to determine the pore structure parameters and reveal their heterogeneity according to Frenkel-Halsey-Hill theory. As suggested by the experimental results, the pore size distribution curve of the N2 and CO2 exhibits similar pore peaks, whereas the trends of change in bulk shale and isolated OM samples are basically paralleled. The pore volume of the isolated OM ranges between 0.034 and 0.056 cm3/g, which is approximately 0.90–3.06 times that of bulk shale samples. As for the fractal dimensions D1 (2.594 on average) and D2 (2.657 on average) of bulk shale, they are larger as compared with isolated OM, indicating that inorganic minerals can make a significant difference in the heterogeneity of shale pores. The fractal dimensions (D1 and D2) of bulk shales indicate a close correlation with the parameters of pore structure, whereas there is no significant correlation observed between the dimensions of isolated OM and its parameters. In addition, thermal maturity and solid bitumen have only limited impact on the OM pore structure of isolated OM samples. Then, we conducted further research to reveal that the insoluble OM macerals derived from terrestrial higher plants can be used to explain the difference in pore structure and heterogeneity between isolated OM samples. Therefore, we arrived at the conclusion that the composition of macerals depends on the exact pore structure and fractal characteristics of isolated OM samples with similarity in thermal maturity.
PubDate: Tue, 27 Dec 2022 00:00:00 GMT
-
- In situ stress field prediction based on seismic data in the Sijiazhuang
mining area-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Accurately predicting the 3D in situ stress field is critical in coal mining. We have proposed a workflow that is based on 3D seismic attributes to predict the in situ stress field of a coal mine located in Sijiazhuang, Shanxi, China. First, we interpreted the faults and folds within our study area. Then, we determine the directions and types of in situ stress by analyzing the interpreted faults and folds. Under the assumption that the process of strata deformation can be simulated by a thin-plate theory, we deduce the equations to compute in situ stress as a function of seismic curvature attribute and elastic parameters inverted from seismic data. We also proposed a stability factor that is based on the computed stress field. The results find that the in situ stress field within our study area is dominated by the compression stress along the northwest–southeast direction. Based on the proposed stability coefficient, we further predicted the zones that have abnormal rock mass stability.
PubDate: Wed, 21 Dec 2022 00:00:00 GMT
-
- Dependence of effective permeability on pore pressure gradient at low flow
rates in low-permeability limestone-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Many researchers note a nonlinearity of flow in tight rock samples at low rates. The effects include changes in apparent permeability with pore pressure gradient and so-called threshold gradients, below which low flow or no flow occurs. It is believed that these effects may be related to the influence of adhesive layers with altered properties at the interfaces between liquid and solid phases. For low-permeable rocks, the estimation of reservoir permeability without taking into account the nonlinearity of the flow can lead to significant errors. An account of the flow nonlinearity also can downgrade the reservoir productivity estimation and may result in underestimation of stationary oil zone appearances. Conventional methods for studying fluid flows in porous rocks are poorly suited for studying their permeability when approaching zero flow rates because of the lack of accuracy. Such studies also require a special approach for the interpretation of the data obtained. At the same time, there is a lack of discussion of the appropriate experimental technique in the publications known. Our goal was to develop a technique suitable for studying the flow nonlinearity at extremely low flow rates. Using the developed experimental technique, we carried out three series of consecutive tests on three similar limestone core samples. The samples were taken from the aquifer; however, their porosity and permeability are similar to the typical parameters of a tight oil reservoir. During the test series, we observed the change in the deviation from the linear Darcy’s law over a long time. We realized that in the sample with the most pronounced deviation from linear flow, there was a most significant decrease in net permeability in the entire series. We believe that our method can provide more precise evaluation of the permeability of tight rocks at the near real flow rate.
PubDate: Wed, 23 Nov 2022 00:00:00 GMT
-
- A well conditioning method of object-based models
-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Reservoir stochastic simulation usually can be divided into two categories: object-based modeling method and pixel-based modeling method. For fluvial reservoirs, the complex geometry of sedimentary microfacies, such as the morphology of channels and natural levees, can be reproduced better by using the object-based methods. But these object-based approaches also have difficulty in conditioning models to dense well data. Most of previous conditional methods are iterative optimization algorithms, which take a long time to reach convergence when there are many conditional data, and they generally obtain a low degree of conditionalization. Therefore, we develop a new conditional methodology. The process of conditioning to well data is as follows. First, the classical object-based method is used to establish the channel reservoir model. Based on this, the distance parameter field (D1) related to the center lines of channels is established. Next, we convert the information of channel and nonchannel wells into the distance from the center lines and then set up the distance parameter field (D2) by kriging and other methods. Finally, D1 is modified by using the logical relationship between D2 and D1, and then D1 is truncated to obtain the river channel model. The analysis of the results of three examples indicates that this new approach can improve the conditional level greatly.
PubDate: Thu, 20 Oct 2022 00:00:00 GMT
-
- Multiple trend integration method based on depositional model and its
application in glutenite reservoir modeling-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Strong heterogeneity, complicated lithology, and chaotic seismic reflection characteristics are all common features of glutenite reservoirs. It is challenging to pinpoint the interior lithology and quantitatively describe the heterogeneity of the single-stage glutenite. To explore the distribution and superimposition features of subaqueous fans, the upper Es4 in the Y229 region of Dongying sag was used as an example. We have developed a multitrend fusion constraint modeling method based on deposition patterns. First, the truncated Gaussian simulation method is used to establish the sedimentary subfacies model of the subaqueous fan. Second, one lithologic probability volume is generated according to the proportion of various lithology of different sedimentary subfacies. Then, the lobes model is constructed using the object-based simulation method and the quantitative parameters from outcrop and flume sedimentation simulations. In addition, a different lithology probability volume is determined based on how far a particular lobe is from the centerline. The two probability volumes are combined to create the integrated lithology probability volume, which reflects the planar trend and the internal differences of different lobes. To constrain lithologic modeling, the integrated lithology probability volume is used. By comparing the model results with a single-trend constraint, the findings indicate that the multitrend integration constraint modeling method may more accurately depict the internal variability of the glutenite reservoir. In addition, the lithologic model built on this foundation is consistent with the depositional model.
PubDate: Tue, 27 Sep 2022 00:00:00 GMT
-
- Sharp change of the channel bar pattern within the river delta: Insights
from modern Ganjiang River delta in Jiangxi province, China-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Channel bars (midchannel bars or point bars) in river deltas present challenges to water transportation; meanwhile, they provide a source of building materials, habitats, and farmlands, and they could become targets in hydrocarbon reservoirs. Researchers focus on the channel bar pattern in rivers, while ignoring the channel bar pattern in distributary channels. We have analyzed a sharp change of the channel bar pattern from the river to the delta. The integration of remote map analysis, fieldwork, and a flume experiment has resulted in a quantified sharp change in the channel bar pattern in the Ganjiang River delta and revealed a hydrodynamic mechanism. The result finds that distributary channels develop much finer-grained, smaller-scale, less channel bars with the lower width-length ratio, compared to the upstream river. Distributary channels develop more point bars and fewer midchannel bars than the upstream braided river, and they develop fewer point bars than the upstream meandering river. Sharply weakening bank erosions in distributary channels lead to the formation of the sharp change in the channel bar pattern from the upstream river, due to backwater effect-induced sharp gentling of landform gradient. The backwater effect impedes bank erosions in the distributary channels, but it promotes bank erosions in upstream rivers, which, in turn, enhances the sharp change of the channel bar pattern. We provide insights into channel bars’ growth in modern river deltas and provide new facies models for the river-delta system.
PubDate: Tue, 27 Sep 2022 00:00:00 GMT
-
- Nonstationary training image partition algorithm based on deep features
-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Training image (TI) is a key input of multipoint geostatistical modeling. For modeling sedimentary facies under nonstationary conditions, it is common to first generate nonstationary TIs, then use a partitioned simulation approach, and finally merge the realizations of each subregion. We develop a new method for partitioning nonstationary TIs based on features extracted using a deep network model. The basic idea of the method is to crop a TI with a sliding window to obtain the subblocks of the TI and use the pretrained convolutional neural network model as a fixed feature extractor for the subblocks. We use K-means to cluster the extracted deep features and t-distributed stochastic neighbor embedding to visualize the clustering effect and assign the classification information of all feature points to the subblocks of the TI as its subregion markers. Finally, we stitch the subblocks of the marked TIs by position to obtain the partitioning results of the nonstationary TIs. Experimental results indicate that the classification accuracy of the method reaches 90.53%, and the partition effect is relatively good. Research indicates that the method can reproduce well the spatial variation characteristics of nonstationary TIs and provide a new method for processing the multipoint geostatistical nonstationarity.
PubDate: Tue, 27 Sep 2022 00:00:00 GMT
-
- Analysis of the main controlling factors and the distribution rules of
effective reservoirs in sandy braided river delta plain — A case study
of Ct3 area, Ordos Basin, China-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: To clarify the main controlling factors of effective reservoirs in the sandy braided river delta plain, the eighth member of Xiashihezi Formation in the Ct3 area, Ordos Basin, is taken as an example. We describe and analyze approximately 600 cores in detail and correspond the cores on the logging curve. We summarize the logging facies mode suitable for the Ct3 area, and finally investigate the types and spatial distribution characteristics of sedimentary microfacies. The P2h8 member of Ct3 area in Ordos Basin is braided river delta plain subfacies. Sedimentary microfacies are divided into three types: distributary channel, channel bar, and distributary interchannel. The sand body in the h84 of the P2h8 member is the thickest, and the number of channel bar is the largest. All gas reservoirs (effective reservoirs) are developed on the sand body of the channel bar, which is the most favorable microfacies type. Poor gas reservoirs are mostly developed in distributary river channel sand body, whereas gas-bearing reservoirs (gas reservoirs and poor gas reservoirs) are undeveloped in distributary interchannel. According to the hydrodynamic conditions and sedimentary mechanism, the channel bar is divided into the bar head, the bar tail, the bar main body, and the bar wing. It is found that 63% of the gas reservoirs in the channel bar are developed in the bar main body, followed by the bar tail. The number of gas reservoirs developed at the bar head and the bar wing is the least. The results found that the most effective reservoirs are developed in the bar main body. Sedimentary microfacies, sand-body thickness, and grain size are the main controlling factors for effective reservoirs. The research results can guide the gas field exploration and later well location deployment in the sedimentary environment similar to the Ct3 area.
PubDate: Mon, 12 Sep 2022 00:00:00 GMT
-
- Sand architecture interpretation and modeling with few wells in the
offshore — Case study of X36 area in the Xihu Depression, East China
Sea, China-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The sand architecture interpretation and modeling of the different orders of sedimentary bodies are of great significance for the efficient development of the unconventional reservoir. However, sand architecture interpretation and modeling using a small amount of observation information are extraordinarily difficult. We took the X36 gas field in Xihu Sag as an example to study the distribution and superimposition characteristics of sandbodies under the influence of tides. We proposed a set of architecture characterization and modeling methods suitable for the condition of a few wells. First, we extracted a variety of seismic attributes from the original seismic data, and we fit the correlations between seismic attributes and sandstone thickness interpreted by logging. Then, we classified and integrated the seismic attributes with a high correlation to calculate the fusion seismic attributes. The fusion seismic attribute has a higher correlation with sandstone thickness. The boundary of the sandstone in the fusion seismic attribute is clearer than a single attribute. We established the sand body distribution model of the study area with the constraints of the fusion seismic attribute and the distance attribute volume. The results indicated that the sand body distribution in the model was more consistent with the sand body development model under the influence of the tide. The results can guide architecture characterization and remaining oil potential tapping of the oil and gas fields offshore.
PubDate: Mon, 22 Aug 2022 00:00:00 GMT
-
