A Study on the Outburst Threshold Value of Gas Content in Coal

2013 ◽  
Vol 295-298 ◽  
pp. 2855-2858
Author(s):  
Sheng Xue ◽  
Liang Yuan ◽  
Jun Xie ◽  
Yu Cang Wang
Keyword(s):  
Numerical Modelling ◽  
Coal Seam ◽  
Field Measurements ◽  
Threshold Value ◽  
Gas Content ◽  
Field Observations ◽  
Underground Coal Mining ◽  
Made In

An outburst of coal and gas is a major hazard in underground coal mining. It occurs when certain conditions of coal stress, strength and gassiness are met. Based mainly on field observations related to the conditions, a number of indices are used in prediction of the outburst. Some of the indices are considered to be inadequate, inappropriate or impractical in some coal seam conditions. Significant progresses have been made in development of the technologies over the last few years. One of the major achievements is an analytical method in determination of an outburst threshold value of the gas content in a coal seam. The method combines field measurements and numerical modelling. The method is illustrated in this paper in a case study for determination of the outburst threshold value of gas content for a coal seam.

Corrosion Metal Loss Interaction From In-Line Inspection and How it Can Affect the Calculated Failure Pressure

2012 ◽  
Author(s):  
Lucinda Smart ◽  
Richard McNealy ◽  
Harvey Haines
Keyword(s):  
Field Measurements ◽  
Metal Loss ◽  
Data Correlation ◽  
Failure Pressure ◽  
Industry Standards ◽  
Direct Measurements ◽  
Non Destructive ◽  
Flux Leakage

In-Line Inspection (ILI) is used to prioritize metal loss conditions based on predicted failure pressure in accordance with methods prescribed in industry standards such as ASME B31G-2009. Corrosion may occur in multiple areas of metal loss that interact and may result in a lower failure pressure than if flaws were analyzed separately. The B31G standard recommends a flaw interaction criterion for ILI metal loss predictions within a longitudinal and circumferential spacing of 3 times wall thickness, but cautions that methods employed for clustering of ILI anomalies should be validated with results from direct measurements in the ditch. Recent advances in non-destructive examination (NDE) and data correlation software have enabled reliable comparisons of ILI burst pressure predictions with the results from in-ditch examination. Data correlation using pattern matching algorithms allows the consideration of detection and reporting thresholds for both ILI and field measurements, and determination of error in the calculated failure pressure prediction attributable to the flaw interaction criterion. This paper presents a case study of magnetic flux leakage ILI failure pressure predictions compared with field results obtained during excavations. The effect of interaction criterion on calculated failure pressure and the probability of an ILI measurement underestimating failure pressure have been studied. We concluded a reason failure pressure specifications do not exist for ILI measurements is because of the variety of possible interaction criteria and data thresholds that can be employed, and demonstrate herein a method for their validation.

scholarly journals Methodology for Determining the Die-Off Coefficient of Enterococci in the Conditions of Transport through the Karst Aquifer—Case Study: Bokanjac–Poličnik Catchment

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 820 ◽  
Author(s):  
Željko Šreng ◽  
Goran Lončar ◽  
Marin Grubišić
Keyword(s):  
Karst Aquifer ◽  
Field Measurements ◽  
Initial Step ◽  
Seepage Flow ◽  
Mean Value ◽  
Dominant Factor ◽  
Karst Environment ◽  
Karst Catchment

This paper presents the methodology for determining the die-off coefficient of faecal indicator bacteria (enterococci) when transported in a karst environment. The main problem in exploring karst environments, which this methodology strives to cope with, is lack of field measurements, poor data on karst rock formation, fractures and channels within it, and groundwater level dynamics. The analysed karst catchment (Bokanjac–Poličnik) is situated in the hinterland of the city of Zadar (Republic of Croatia) and covers an area of 235.07 km2. In the water supply wells within the analysed catchment, a frequent occurrence of enterococci was observed. The proposed methodology consists of two basic steps. Preliminary analyses as the initial step were used in the accumulation of certain assumptions related to the detection of increased concentrations of enterococci as well as in determination of the potential source of pollution. In the second step, the analytical model was constructed with the aim of resolving processes of sorption and die-off and determining the dominant factor in the process of natural removal of enterococci when transported in karst environment. Within the model, two parts of the pollutant transport are integrated: vertical percolation and horizontal seepage flow and transport. The mean value of the total die-off coefficient by transport through the unsaturated zone in the analysed case is k t o t = 8.25. Within the saturated zone the total die-off coefficient k t o t is within the limits of 0.1 and 0.5.

Determination of "Double Control" Management Threshold Value for Groundwater Based on GMS -- A Case Study of Changchun City, Jilin Province

2020 ◽  
Author(s):  
Linlin Qi ◽  
Xiaoying Zhang ◽  
Zhenxue Dai ◽  
Sida Jia ◽  
Funing Ma
Keyword(s):  
Groundwater Management ◽  
Groundwater Level ◽  
Groundwater Resources ◽  
Threshold Value ◽  
Jilin Province ◽  
Dual Control ◽  
Changchun City ◽  
Control Management

<p>Determination of "Double Control" Management Threshold Value for Groundwater Based on GMS -- A Case Study of Changchun City, Jilin Province</p><p>Linlin Qi<sup>1</sup>, Xiaoying Zhang<sup>1</sup>, Zhenxue Dai<sup>1</sup>, Sida Jia<sup> 1</sup>, Funing Ma <sup>1</sup></p><p>（1. College of Construction Engineering, Jilin university, Changchun 130021, China）</p><p>Groundwater is an essential controlling factor for economic and social development, human survival and good ecological environment. Many areas use groundwater as a regular source of water. However, with the development of economy and society, water pollution problems keep emerging, water resources crisis is increasingly serious, especially in the northern water resources shortage areas, so groundwater management is particularly important. It is no longer possible to objectively reflect the groundwater safety situation in a certain area by controlling the amount of groundwater mining or the groundwater level. Therefore, it is necessary to construct the groundwater “dual-control” management mode. However, the foundation of “dual-control” management is to establish the mathematical relationship between the groundwater control level and the amount of groundwater mining. Taking Changchun city in Jilin province as an example, the study area was divided into different management zones, and the threshold value about the groundwater level and the amount of groundwater mining were determined by analytical method. Then using GMS software to establish a model of groundwater resources in the study area. After identification authentication model to simulate the groundwater resources and the relationship between the groundwater table, ultimately determine the threshold value of groundwater level and water quantity under dual control management in this area. It can be used as the most intuitive data of groundwater dual control management and control. With the groundwater protection as the starting point and the sustainable utilization of resources as the goal, it will be the focus of future research in China to establish the groundwater management mode of "water level" and "water quantity", in order to make the groundwater management more flexible, controllable and scientific.</p>

Study and Application on a New Type of Rapid Determination Model of Gas Content

2014 ◽  
Vol 962-965 ◽  
pp. 1201-1204
Author(s):  
Xiao Hua Jin ◽  
Bei Fang Gu ◽  
San Feng Bai ◽  
Xin Yao Guo ◽  
Ming Gang Luo
Keyword(s):  
Linear Regression ◽  
Coal Seam ◽  
Rapid Determination ◽  
Gas Content ◽  
Characteristic Parameters ◽  
Accuracy Rate ◽  
Theoretical Derivation ◽  
Residual Amount ◽  
New Type

Against the problem of calculating gas content rapidly, this article studied the desorption characteristics of coal by measuring the characteristic parameters of coal in the laboratory. With the actually measured amount of desorption and the desorption rule of the coal within the first 30min, through theoretical derivation and Multiple Linear Regression, the gas content desorbs within the first 120min and the residual amount after a 120min of coal desorption is studied and confirmed Based on the rapid determination model of gas content in the coal seam is established, and the new model is verified, whose accuracy rate reaches above 85%. If relevant electronic equipments were made, this method would be able to give a result within 40min, thereby realizing the rapid determination of gas content in the coal seam within the gas belt.

scholarly journals Determination of the Height of the Water-Conducting Fractured Zone in Difficult Geological Structures: A Case Study in Zhao Gu No. 1 Coal Seam

2017 ◽  
Vol 9 (7) ◽  
pp. 1077 ◽  
Author(s):  
Shuai Zhang ◽  
Shijie Tang ◽  
Dongsheng Zhang ◽  
Gangwei Fan ◽  
Zhen Wang
Keyword(s):  
Coal Seam ◽  
Geological Structures ◽  
Fractured Zone

scholarly journals Implications of Child Custody in Islamic Family Law: A Case Study of Customary Courts in Oyo State, Nigeria

ICR Journal ◽  
2018 ◽  
Vol 9 (3) ◽  
pp. 362-376
Author(s):  
Aminullahi Adetoro Yusuff
Keyword(s):  
Child Custody ◽  
Family Law ◽  
The State ◽  
Real Problem ◽  
Marital Discord ◽  
Civil Unrest ◽  
Custody Of Children ◽  
Made In

Studies carried out to investigate the immediate and remote causes of marital discord arising from many of the customary courts in Oyo State, Nigeria, revealed that out of 127 divorce-related cases, 87 involved Muslim couples. Out of this number, 53 were linked to custody of children (al-hadanah which is a regulation that has to do with whom should a child stay after the dissolution of marriage for his/her proper nourishment, protection and wellness in the process of upbringing). This issue has led to many serious disputes among Muslim couples and their families in many localities of the state so much that, in many cases, it has led to street fights, vandalisation of property, civil unrest and legal battles. To worsen the situation, without recourse to Islamic marital jurisprudence, judgments are passed in the customary courts in favour of either of the couples. Therefore, the aftermath of the court verdict does not end this debacle in some cases, with to snowballing into spiritual fighting, where family members of the couples bewitch one another to take custody of the children. This problem is not new but it has risen to an alarming proportion these days. It is against this backdrop that an attempt is made in this paper to examine the practice of child custody after divorce or separation in Islam with a view to laying to rest the series of crises associated with the determination of who is to take care of children after divorce and to bring to peoples awareness the shariah rulings on child custody. The paper concludes that al-hadanah is a measure in disguise to safeguard indiscriminate severance of the cord of marriage and that Islam, through its system of law, has provided practical and lasting solutions to every imagined and real problem of man and that adoption of children in its various forms and types is forbidden in Islam.

scholarly journals Cement bond evaluation using well logs: A case study in Raniganj Block Durgapur, West Bengal, India

2021 ◽  
Vol 11 (4) ◽  
pp. 1743-1749
Author(s):  
Prashant Saini ◽  
Harinandan Kumar ◽  
Tarun Gaur
Keyword(s):  
Coal Seam ◽  
West Bengal ◽  
Variable Density ◽  
Well Logs ◽  
Well Testing ◽  
Production Operation ◽  
Bond Evaluation

AbstractCement bond logs (CBL) and variable density log (VDL) are one of the vital logging techniques used to evaluate cement-casing-formation bonds before the well testing or execution of the production operation in the well. These logs are also crucial during the workover operation to maintain the integrity of the well. The logging techniques provide a clear view of the quality of cement bonds with casing and formation. The microannulus and other deviations in bonding between the cement and the casing or formation are recorded using this technique. Therefore, this technique is used by the regulatory authorities worldwide for the determination of the cement bond with casing and formation. In this paper, the CBL/VDL logging technique was used to determine the bonding between cement and casing and cement and formation at two different CBM wells from 850 to 1600 m depths in the Raniganj block of Durgapur, West Bengal. Two well, namely, A and B, were analyzed to determine the cement-casing-formation bonds in the study area's coal seam zone. The analysis was carried out at normal and pressure pass to investigate the integrity of the well using the CBL/VDL data. The normal and pressure pass in well A indicated the presence of microannulus in the bonding between cement and casing/formation in the coal seam zone. The corresponding analysis of well B showed poor cement and formation bond at the coal seam zone during the normal pass but good bonding after the pressure pass. Thus, it was observed that the CBL/VDL data were capable of determining the cement-casing-formation bonds in both the well of the study area and the well's integrity.

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