Estimation of In Situ Stresses by Using Hydraulic Fracturing and Welllogging Data in Shizhuangnan Coalbed Methane Field

2013 ◽  
Vol 734-737 ◽  
pp. 56-59
Author(s):  
Zhi Qiang Liu ◽  
Li Ren Xing ◽  
Ru Min Liu
Keyword(s):  
Residual Stress ◽  
Coalbed Methane ◽  
Gamma Ray ◽  
Ordos Basin ◽  
Complex Structure ◽  
Breakdown Pressure ◽  
Natural Gamma ◽  
Ray Density ◽  
Distribution Of Stress

This paper focuses on the research of the vertical and regional distributions of stress characteristics in the Shizhuangnan coalbed methane field, southeastern Ordos basin. The minimum and maximum horizontal stresses were firstly calculated by the breakdown pressure, closure pressure and tensile strength of the fracturing data of key wells. Then the calculated results are compared with the results calculated from the natural gamma-ray, density and acoustic logging data and Anderson’s Model. Based on the comparison, the residual stress in the Anderson’s Model is corrected. By adding the residual stress data in the Anderson’s Model, the modified model can be well used for evaluating the stress characteristics in the area with complex structure types. Finally, the distribution of stress characteristics in the Shizhuangnan coalbed methane field were evaluated by using the modified Anderson model.

Evaluation of the Gas Content of Coal Reservoirs with Geophysical Logging in Weibei Coalbed Methane Field, Southeastern Ordos Basin, China

2013 ◽  
Vol 734-737 ◽  
pp. 331-334
Author(s):  
Tao Tao Yan ◽  
Zhi Qiang Liu ◽  
Li Ren Xing ◽  
Yong Luo ◽  
Ya Dong Bai ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Gamma Ray ◽  
Ordos Basin ◽  
Measured Data ◽  
Gas Content ◽  
Burial Depth ◽  
Geophysical Logging ◽  
Natural Gamma ◽  
Geophysical Logs ◽  
Movement Intensity

Gas content is one of the most important factors in the process of exploration and development of coalbed methane (CBM). The relationships between gas content and characteristics of geophysical logs have been evaluated for the No. 5 coal seam in Weibei CBM field. It is found that the main well loggings that have good responses for gas contents are the compensating density, natural gamma-ray, compensating neutron, natural spontaneous potential and acoustic. A theoretical model was proposed to calculate the gas content by using these well logging data and as well as the burial depth. The calculated gas contents fits well with the measured data with a small relative-error of 0.38-5.05%. In the model, both tectonic movement intensity and the gas accumulation were taken into consideration. Key words: Coalbed methane, Weibei coalfield, Ordos Basin, Gas content, Geophysical logging

THE NATURAL GAMMA‐RAY FLUX: IN‐SITU ANALYSIS

Geophysics ◽  
1968 ◽  
Vol 33 (2) ◽  
pp. 311-328 ◽  
Author(s):  
Ronald Doig
Keyword(s):  
Gamma Ray ◽  
Background Radiation ◽  
In Situ Analysis ◽  
Rock Outcrops ◽  
Large Sample ◽  
Gamma Ray Spectrometer ◽  
Natural Gamma ◽  
Major Project ◽  
Quantitative Evaluations

A fully portable transistorized gamma‐ray spectrometer has been constructed, and used to investigate the nature of the gamma ray activity at the surface of rock outcrops. Gamma‐ray photopeaks of [Formula: see text] and members of the U and Th series have been identified, along with strong fallout activity dominated by the 0.75 Mev activity of [Formula: see text]. A method has been devised for measuring, in situ, the K, U, and Th contents of rocks. Calibration accounts for the interference between the radioelements, and for background radiation. The following estimates of accuracy and sensitivity are for five‐minute counting intervals: 5 percent plus 0.1 percent K, 10 percent plus 0.2 ppm U, 10 percent plus 0.5 ppm Th. The main advantages of the method are its speed and versatility and the very large sample analyzed. A number of surveys have been performed to demonstrate some of the applications of the instrument. The major project of this series is detailed mapping of the K, U, and Th distribution in the Preissac granite of northwestern Quebec. In addition to its use as a petrologic tool, the technique is eminently suited to prospecting for U and Th, and the quantitative evaluations of occurrence of these elements.

Geophysical and geochemical logs from a copper oxide deposit, Santa Cruz project, Casa Grande, Arizona

Geophysics ◽  
1994 ◽  
Vol 59 (12) ◽  
pp. 1827-1838 ◽  
Author(s):  
Philip H. Nelson ◽  
David Johnston
Keyword(s):  
Copper Oxide ◽  
Rock Strength ◽  
Gamma Ray ◽  
Petroleum Industry ◽  
Mechanical Tests ◽  
Close Link ◽  
Natural Gamma ◽  
Oxide Deposit ◽  
Copper Distribution

In support of an in‐situ leaching experiment, five holes drilled into a copper oxide deposit have been logged with geophysical and geochemical tools developed for use in the petroleum industry. When combined with geological description, chemical analyses, and mineralogical data from core and cuttings, the logs provide information regarding the alteration, fracturing, copper distribution, porosity, and permeable zones. Correlations among sonic velocity, rock strength from mechanical tests on core, and alteration indicators from neutron and potassium logs demonstrate a close link between the state of alteration and the mechanical state of the rock. Neutron activation, natural gamma‐ray, and density logs, in combination, correlate so well with copper assays that log‐based prediction of copper content is possible; in addition, an estimate of whole‐rock mineralogy is presented in log format. Based on comparisons of flow logs and acoustic logs obtained in the same holes, reductions in acoustic velocity appear to be the best indicators of permeability increases.

scholarly journals In Situ Stress Distribution and Its Control on the Coalbed Methane Reservoir Permeability in Liulin Area, Eastern Ordos Basin, China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Peng Feng ◽  
Song Li ◽  
Dazhen Tang ◽  
Liangjun Wu ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Ordos Basin ◽  
In Situ Stress ◽  
Burial Depth ◽  
Lateral Stress ◽  
High Permeability ◽  
Depth Zone ◽  
Stress Coefficient ◽  
Lateral Stress Coefficient

Permeability is one of the important factors that affect the production efficiency of coalbed methane, and it is mainly controlled by in situ stress. Therefore, it is very essential to study the in situ stress and permeability for the extraction of coalbed methane. Based on the injection/falloff well test and in situ stress measurement of 35 coalbed methane wells in the Liulin area in the east of the Ordos basin, the correlations between initial reservoir pressure, in situ stress, lateral stress coefficient, permeability, and burial depth were determined. Finally, the distribution characteristics of in situ stress and its influence on permeability were analyzed systematically. The results show that with the increase of burial depth, the initial reservoir pressure and in situ stress both increase, while the lateral stress coefficient decreases. The permeability variation is related to the type of stress field in different burial depths, and its essence is the deformation and destruction of coal pore structures caused by stress. The distribution characteristics of in situ stress at different depths and its effect on permeability are as follows: at depths < 800   m , the horizontal principal stress is dominant ( σ H ≥ σ v > σ h ) and the permeability is a simple decreasing process with the increase of the depth; at depths > 800   m , the vertical stress is dominant ( σ v ≥ σ H > σ h ). The permeability of most coal is very small due to the large in situ stresses in this depth zone. However, because of the stress release at the syncline axis, coal with high permeability is still possible at this depth zone. Due to the existence of high permeability data points at burial depth (>800 m) and the fitting relationship between permeability and vertical stress, the maximum and minimum horizontal principal stress is poor. However, the coal permeability and lateral stress coefficient show a good negative exponential relationship. This indicates that the lateral stress coefficient can be used to predict permeability better.

Study on the Regularity of the Natural Gamma-Rays Attenuation in the Slurry Water

2012 ◽  
Vol 468-471 ◽  
pp. 1031-1035 ◽  
Author(s):  
Cheng Lian Zhang
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Water Concentration ◽  
Coal Preparation ◽  
Sand Beach ◽  
Natural Gamma ◽  
Ray Density ◽  
Radioactive Sources ◽  
Coal Preparation Plant ◽  
Preparation Plant

Gamma-ray density meter has been widely used in coal preparation plant to detect the concentration of the slurry water, but it require annual inspection, approval, and the protection of the radioactive sources causes a lot of inconvenience to the coal preparation plant. In this paper a natural mineral sand beach has been chosen as radioactive sources, which contains thorium. An experimental device has been designed to detect the concentration of the slurry water, the natural gamma-rays attenuation rules were obtained after lots of experiments in the laboratory when it passing through the different concentration of the slurry water, and the rules were proved in theory and in tests. This provides reliable basis for design of slurry water concentration measurement device.

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