scholarly journals Classification evaluation method for Chang 7 oil group of Yanchang formation in Ordos Basin

2021 ◽  
Author(s):  
Fan Jianming ◽  
Shi Jian ◽  
Wan Xiaolong ◽  
Xie Qichao ◽  
Wang Chong
Keyword(s):  
Evaluation Method ◽  
Layer Structure ◽  
Ordos Basin ◽  
Pressure Coefficient ◽  
Correlation Method ◽  
Difficult Problem ◽  
Throat Radius ◽  
Average Pore ◽  
Classification Evaluation ◽  
Evaluation Parameters

AbstractThe Chang 7 oil group in the Ordos Basin has the characteristics of a tight lithology, a low formation pressure coefficient and strong reservoir heterogeneity. To better determine reasonable developmental technical countermeasures, oiliness, seepage capacity, and compressibility evaluations are combined. Using a combination of field practice and laboratory experiments, six types of sweetness classification evaluation parameters are screened: oil saturation, longitudinal oil layer structure coefficient, average pore throat radius, gas-oil ratio, brittleness index, and minimum horizontal principal stress. By combining the relationships among variables with the initial production from directional wells, the gray correlation method is used to quantify the weights of the contributions of evaluation parameters to production. On this basis, using the difference method for the curve slope, a sweetness evaluation and classification method for the Chang 7 oil group is constructed, and it solves the difficult problem of quality difference classification for the Chang 7 oil group and provides a reference basis for the optimal design of well patterns and fracturing reconstruction parameters.

scholarly journals Microscale Pore Throat Differentiation and Its Influence on the Distribution of Movable Fluid in Tight Sandstone Reservoirs

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Fengjuan Dong ◽  
Xuefei Lu ◽  
Yuan Cao ◽  
Xinjiu Rao ◽  
Zeyong Sun
Keyword(s):  
Ordos Basin ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Throat Radius ◽  
Thin Sections ◽  
Small Pore ◽  
Sandstone Reservoir ◽  
Sandstone Reservoirs ◽  
Classification Evaluation ◽  
Better Than

Tight sandstone reservoirs have small pore throat sizes and complex pore structures. Taking the Chang 6 tight sandstone reservoir in the Huaqing area of the Ordos Basin as an example, based on casting thin sections, nuclear magnetic resonance experiments, and modal analysis of pore size distribution characteristics, the Chang 6 tight sandstone reservoir in the study area can be divided into two types: wide bimodal mode reservoirs and asymmetric bimodal mode reservoirs. Based on the information entropy theory, the concept of “the entropy of microscale pore throats” is proposed to characterize the microscale pore throat differentiation of different reservoirs, and its influence on the distribution of movable fluid is discussed. There were significant differences in the entropy of the pore throat radius at different scales, which were mainly shown as follows: the entropy of the pore throat radius of 0.01~0.1 μm, >0.1 μm, and <0.01 μm decreased successively; that is, the complexity of the pore throat structure decreased successively. The correlation between the number of movable fluid occurrences on different scales of pore throats and the entropy of microscale pore throats in different reservoirs is also different, which is mainly shown as follows: in the intervals of >0.1 μm and 0.01~0.1 μm, the positive correlation between the occurrence quantity of movable fluid in the wide bimodal mode reservoir is better than that in the asymmetric bimodal mode reservoir. However, there was a negative correlation between the entropy of the pore throat radius and the number of fluid occurrences in the two types of reservoirs in the pore throat radius of <0.01 μm. Therefore, pore throats of >0.1 μm and 0.01~0.1 μm play a controlling role in studying the complexity of the microscopic pore throat structure and the distribution of movable fluid in the Chang 6 tight sandstone reservoir. The above results deepen the understanding of the pore throat structure of tight sandstone reservoirs and present guiding significance for classification evaluation, quantitative characterization, and efficient development of tight sandstone reservoirs.

Non-Axisymmetric Turbine Endwall Aerodynamic Optimization Design: Part I — Turbine Cascade Design and Experimental Validations

2014 ◽  
Author(s):  
Hao Sun ◽  
Jun Li ◽  
Liming Song ◽  
Zhenping Feng
Keyword(s):  
Secondary Flow ◽  
Evaluation Method ◽  
Pressure Coefficient ◽  
Optimization Method ◽  
Experimental Measurements ◽  
Turbine Cascade ◽  
Aerodynamic Optimization ◽  
Flow Losses ◽  
Flow Intensity ◽  
Performance Evaluation Method

The non-axisymmetric endwall profiling has been proven to be an effective tool to reduce the secondary flow loss in turbomachinery. In this work, the aerodynamic optimization for the non-axisymmetric endwall profile of the turbine cascade and stage was presented and the design results were validated by annular cascade experimental measurements and numerical simulations. The parametric method of the non-axisymmetric endwall profile was proposed based on the relation between the pressure field variation and the secondary flow intensity. The optimization system combines with the non-axisymmetric endwall parameterization method, global optimization method of the adaptive range differential evolution algorithm and the aerodynamic performance evaluation method using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) and k–ω SST turbulent with transition model solutions. In the part I, the optimization method is used to design the optimum non-axisymmetric endwall profile of the typical high loaded turbine stator. The design objective was selected for the maximum total pressure coefficient with constrains on the mass flow rate and outlet flow angle. Only five design variables are needed for one endwall to search the optimum non-axisymmetric endwall profile. The optimized non-axisymmetric endwall profile of turbine cascade demonstrated an improvement of total pressure coefficient of 0.21% absolutely, comparing with the referenced axisymmetric endwall design case. The reliability of the numerical calculation used in the aerodynamic performance evaluation method and the optimization result were validated by the annular vane experimental measurements. The static pressure distribution at midspan was measured while the cascade flow field was measured with the five-hole probe for both the referenced axisymmetric and optimized non-axisymmetric endwall profile cascades. Both the experimental measurements and numerical simulations demonstrated that both the secondary flow losses and the profile loss of the optimized non-axisymmetric endwall profile cascade were significantly reduced by comparison of the referenced axisymmetric case. The weakening of the secondary flow of the optimized non-axisymmetric endwall profile design was also proven by the secondary flow vector results in the experiment. The detailed flow mechanism of the secondary flow losses reduction in the non-axisymmetric endwall profile cascade was analyzed by investigating the relation between the change of the pressure gradient and the variation of the secondary flow intensity.

scholarly journals Multifractal Characteristics and Classification of Tight Sandstone Reservoirs: A Case Study from the Triassic Yanchang Formation, Ordos Basin, China

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2242 ◽  
Author(s):  
Zhihao Jiang ◽  
Zhiqiang Mao ◽  
Yujiang Shi ◽  
Daxing Wang
Keyword(s):  
Pore Structure ◽  
Ordos Basin ◽  
Type I ◽  
Tight Sandstone ◽  
Throat Radius ◽  
Yanchang Formation ◽  
Porosity And Permeability ◽  
Sandstone Reservoir ◽  
And Migration ◽  
Mercury Injection Capillary Pressure

Pore structure determines the ability of fluid storage and migration in rocks, expressed as porosity and permeability in the macroscopic aspects, and the pore throat radius in the microcosmic aspects. However, complex pore structure and strong heterogeneity make the accurate description of the tight sandstone reservoir of the Triassic Yanchang Formation, Ordos Basin, China still a problem. In this paper, mercury injection capillary pressure (MICP) parameters were applied to characterize the heterogeneity of pore structure, and three types of pore structure were divided, from high to low quality and defined as Type I, Type II and Type III, separately. Then, the multifractal analysis based on the MICP data was conducted to investigate the heterogeneity of the tight sandstone reservoir. The relationships among physical properties, MICP parameters and a series of multifractal parameters have been detailed analyzed. The results showed that four multifractal parameters, singularity exponent parameter (αmin), generalized dimension parameter (Dmax), information dimension (D1), and correlation dimension (D2) were in good correlations with the porosity and permeability, which can well characterize the pore structure and reservoir heterogeneity of the study area, while the others didn’t respond well. Meanwhile, there also were good relationships between these multifractal and MICP parameters.

The Performance Evaluation of Old Well after SRV in Ordos Basin Tight Oil Reservoir

2014 ◽  
Author(s):  
H.. Wang ◽  
X.. Liao ◽  
H.. Ye ◽  
X.. Zhao ◽  
C.. Liao ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Ordos Basin ◽  
Fracture Network ◽  
Water Flooding ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Well Test ◽  
Stimulated Reservoir Volume ◽  
Tight Oil Reservoir ◽  
Volume Fracturing

Abstract The technology of Stimulated reservoir volume (SRV) has been the key technology for unconventional reservoir development, it can create fracture network in formation and increase the contact area between fracture surface and matrix, thus realizing the three-dimensional stimulation and enhancing single well productivity and ultimate recovery. In China, the Ordos Basin contains large areas of tight oil reservoir with the porosity of 2~12 % and permeability of 0.01~1 mD. The most used development mode is conventional fracturing and water flooding, which is different from the natural depletion mode in oversea, but the development effect is still unfavorable. The idea of SRV is proposed in nearly two years in Changqing Oilfield. SRV measures are implemented in some old wells in tight oil formation. It is a significant problem that should be solved urgently about how to evaluate the volume fracturing effect. Based on the real cases of old wells with SRV measures, the microseismic monitoring is used to analyze the scale of formation stimulation and the complexity of fracture network after volume fracturing; the numerical well test and production data analysis (PDA) are selected to explain the well test data, to analyze the dynamic data, and to compare the changes of formation parameters, fluid parameters and plane streamlines before and after volume fracturing; then the interpretation results of well test with the dynamic of oil and water wells are combined to evaluate the stimulation results of old wells after SRV. This paper has presented a set of screening criteria and an evaluation method of fracturing effect for old well with SRV in tight oil reservoir. It will be helpful to the selection of candidate well and volume fracturing operation in Ordos Basin tight oil reservoir. It should be noted that the evaluation method mentioned in the paper can be expanded to volume stimulation effect evaluation in other unconventional reservoirs, such as tight gas, shale gas and so on.

scholarly journals Evaluation method for resource potential of shale oil in the Triassic Yanchang Formation of the Ordos Basin, China

2020 ◽  
Vol 38 (4) ◽  
pp. 841-866
Author(s):  
Qiulin Guo ◽  
Xiaoming Chen ◽  
Xiaoxue Liuzhuang ◽  
Zhi Yang ◽  
Man Zheng ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Calculation Method ◽  
Evaluation Method ◽  
Ordos Basin ◽  
Oil Yield ◽  
Shale Oil ◽  
Recovery Coefficient ◽  
Evaporative Loss ◽  
Total Oil

The widely distributed, thick Chang 7 Shale is the richest shale oil formation in China. A calculation method for the evaporative hydrocarbon recovery coefficient based on formation volume factor is proposed considering the correction of heterogeneity-based total organic carbon differences to improve the adsorbed oil calculation method, and light hydrocarbon evaporative sampling losses, which can make mobile and total oil calculations more accurate. The adsorbed oil, S1 evaporative loss, total oil yield, and movable oil yield of 200 shale samples from the Chang 7 Member were calculated using the new methods. Results show that S1 evaporative loss accounts for 29% of S1, total oil yield is 3.5 times S1, and movable oil yield accounts for 37% of total oil yield. Based on the calculated total oil yield and movable oil yield results, the relationships among total oil yield, movable oil yield, and total organic carbon of the Chang 7 were established yielding total oil yield and movable oil yield estimates of 11.12 × 109 t and 4.01 × 109 t, respectively, revealing its tremendous shale exploration potential.

Description of Gas Hydrate Using Digital Core Technology

2019 ◽  
Vol 142 (6) ◽  
Author(s):  
Shuxia Li ◽  
Shuang Li ◽  
Weixin Pang
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Pore Radius ◽  
Absolute Permeability ◽  
Pore Network Model ◽  
Physical Parameters ◽  
Throat Radius ◽  
Average Pore ◽  
Core Technology ◽  
Digital Core

Abstract As a new energy source with abundant resources, clean combustion, and high calorific value, gas hydrates have received much attention in recent years. However, the sampling cost is relatively high because the gas hydrates exist in deep seas and frozen soils. Digital core technology can reconstruct hydrate cores without destroying rock samples. In this paper, the advanced image processing technology is used to process the gas hydrate computed tomography (CT) scan image, and a three-dimensional hydrate digital core model is constructed, which can depict the sample's pore structure features. avizo software is used for filtering and image segmentation; the porosity is calculated as 35.90%, the hydrate saturation is 36.92%, and the pore network model is established. The pore radius is mostly distributed in 0–1 × 102 µm, and the average pore radius is 168.131 µm; the throat radius is mostly distributed in 0.5–1×102 µm. The seepage simulation on the pore scale is carried out, and the absolute permeability is calculated to be 76.8 µm2. Compared with conventional physical experiments, the digital core technology can obtain the true distribution of the pores inside the hydrate core, which is very helpful for analyzing the physical parameters of the hydrate core. The digital core technology is of great significance in the study of hydrate reservoirs.

An Evaluation Method Based on Grey Incidence Coefficient and Double-Point Method

2011 ◽  
Vol 50-51 ◽  
pp. 766-769
Author(s):  
Pu Yu Hao ◽  
Bao Feng Li ◽  
Yu Huan Cui
Keyword(s):  
Principal Component Analysis ◽  
Correlation Matrix ◽  
Double Point ◽  
Evaluation Method ◽  
Correlation Method ◽  
Principal Component ◽  
Point Method ◽  
Economic Indicators ◽  
Evaluation Indexes ◽  
Main Factors

To one company, it takes 8 major economic indicators as evaluation indexes. Firstly, it uses correlation method to determine the weight and uses the double-point method to sort the 8-years comprehensive economic enterprises. Then through the analysis of the correlation matrix, it identifies the main factors. Finally, the ranking and principal component analysis results are compared and analyzed.

Comprehensive Evaluation for Putaohua Reservoir in Sanzhao Depression

2011 ◽  
Vol 361-363 ◽  
pp. 400-407
Author(s):  
Ji Yu Liu ◽  
Wei Feng ◽  
Sen Lin Gan
Keyword(s):  
Oil Recovery ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Scientific Basis ◽  
Correct Evaluation ◽  
Geological Characteristics ◽  
Oil Distribution ◽  
Comprehensive Classification ◽  
Evaluation Parameters ◽  
Geological Background

With complicated geological background, Putaohua reservoir in Sanzhao depression has lots of blocks. Based on its distribution characteristics and evaluation unit division as well as combined with detailed geological characteristics, parameters of developed and undeveloped blocks were optimized and the comprehensive evaluation parameters were determined. In order to make a correct evaluation for oil content, oil distribution, reservoir physical properties and productivity, this paper has adopted comprehensive quantitative evaluation method to do the comprehensive classification and evaluation for developed and undeveloped blocks. It can not only further improve oil recovery of developed blocks but also provide scientific basis for selecting favorable blocks for productivity construction of undeveloped blocks. According to the classification standard, the developed and undeveloped blocks of Putaohua reservoir in Sanzhao depression were separately divided into three types including Class Ⅰ, Ⅱand Ⅲ. In view of the geology and development factors, undeveloped blocks of Class Ⅰ are equivalent to developed blocks of Class Ⅱ; undeveloped blocks of Class Ⅱ are equivalent to developed blocks of Class Ⅲ; undeveloped blocks of Class Ⅲ are the poorest of all.

scholarly journals A New Evaluation Method of Shale Oil Sweet Spots in Chinese Lacustrine Basin and Its Application

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5519
Author(s):  
Xiaodong Li ◽  
Ketong Chen ◽  
Peng Li ◽  
Junqian Li ◽  
Haiyan Geng ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Pressure Coefficient ◽  
Weighting Factor ◽  
Oil Reservoir ◽  
Bohai Bay ◽  
Shale Oil ◽  
Sweet Spot ◽  
Average Value ◽  
Lacustrine Basin ◽  
Sweet Spots

Compared with the marine shale from North America, Chinese lacustrine basins have more complex geological and reservoir conditions, which makes the selection of sweet spot intervals in the shale oil reservoir particularly difficult. It is thus crucial to accurately predict the shale oil sweet spots for effective exploration and development of shale oil in a lacustrine basin. In this paper, we propose an innovative evaluation method of shale oil sweet spots, which considers five primary parameters (i.e., total oil content, movable oil ratio, reservoir pressure coefficient, permeability, and rock brittleness index) to construct a comprehensive weighting factor, which is used to quantitatively identify a favorable shale oil reservoir. This method firstly constructs an evaluation function for each of the parameters, and then calculates a comprehensive weighting factor to determine the shale oil sweet spot. Statistical results show that the oil production of formation testing intervals have a good positive correlation with the average value of the comprehensive weighting factor of the intervals, which verifies the feasibility of the method. Based on this method, one of the key exploratory wells, Qiang21 in the Raoyang Sag of Bohai Bay basin, was selected as a case study and was determined to be a sweet spot interval of the shale oil reservoir in the upper third member of the Shahejie Formation. This study provides a new way to obtain a favorable exploration interval of shale oil reservoirs and serves shale oil development.

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