An Experimental Study on the Observation Method of Hydrogen Concentration in Fault Gas

In order to explore the new technology and methods for seismic underground fluid observation,a test study on measurement of hydrogen concentration in fault gas is carried out at the piedmont fault zone of Zhongtiao Mountain. Through the experiment on observation positions,gas collection devices and sampling depths,the paper presents the observation method for fault gas hydrogen concentration by using an online automatic trace hydrogen analyzer. Comparative tests are conducted on the stability and optimum conditions of this type of instrument in the field environment, and the hydrogen concentrations at different measuring points of the same fault are observed. The results show that it is technically feasible to carry out continuous hydrogen concentration on a fault zone. The method proposed in this study could be a useful tool for setting the observation points,choosing a reasonable observation depth and scientific analysis of the observed data.

Comparative study on degassing activities along the north fault zone of Western Qinling

Through the comparative studies of degassing activities between the eastern and the western segments, between two pull-apart regions, and between the major fault and branch fault along the north fault zone of Western Qinling (NFZWQ) in 1996 and 1997, the characteristics of degassing activities along NFZWQ were discussed in the paper.With the comparative studies of faulting and seismic activities, this paper points out the role of the degassing activity (CO2, N2, O2 and CO2/O2) in predicting and determining seismicity and faulting activity.

Fault Systems and their Control of Deep Gas Accumulations in Xujiaweizi Area

A study of faults and their control of deep gas accumulations has been made on the basis of dividing fault systems in the Xujiaweizi area. The study indicates two sets of fault systems are developed vertically in the Xujiaweizi area, including a lower fault system and an upper fault system. Formed in the period of the Huoshiling Formation to Yingcheng Formation, the lower fault system consists of five fault systems including Xuxi strike-slip extensional fault system, NE-trending extensional fault system, near-EW-trending regulating fault system, Xuzhong strike-slip fault system and Xudong strike-slip fault system. Formed in the period of Qingshankou Formation to Yaojia Formation, the upper fault system was affected mainly by the boundary conditions of the lower fault system, and thus plenty of muiti-directionally distributed dense fault zones were formed in the T2 reflection horizon. The Xuxi fault controlled the formation and distribution of Shahezi coal-measure source rocks, and Xuzhong and Xndong faults controlled the formation and distribution of volcanic reservoirs of Y1 Member and Y3 Member, respectively. In the forming period of the upper fault system, the Xuzhong fault was of successive strong activities and directly connected gas source rock reservoirs and volcanic reservoirs, so it is a strongly-charged direct gas source fault. The volcanic reservoir development zones of good physical properties that may be found near the Xuzhong fault are the favorable target zones for the next exploration of deep gas accumulations in Xujiaweizi area.

Tectonic evolution of the Changling fault basin and its relationship to oil and gas accumulation

The Changling fault depression passed through three stages of evolution: a period of faulting, a period of subsidence, and an inversion period. The fault lifted the whole area and the formation was eroded during the late Yingcheng formation, the late Nenjiang formation, and the late Mingshui formation. The denudation quantity of eight wells located in the study area is estimated by the interval transit time method and by the formation trend extension method using seismic and drilling data. Inversion back stripping technology with de-compaction correction was used to restore the original sedimentary thickness step by step and to recover the burial history at a single well. Two profiles were selected for the recovery and study of the tectonic evolution. The study confirmed that the primary major gas bearing structure formed due to thermal shrinkage lifting during the late Yingcheng formation. Successive development in a pattern during the late Mingshui formation led to the formation of the primary gas pool. Vertical differential uplift during the late Nenjiang formation formed the Fulongquan structure during the late Paleogene. At this same time a secondary gas pool formed. A large scale reverse developed late in the Mingshui formation that provided the impetus for formation of a secondary gas pool. It is thought that the migration and accumulation of oil and gas was controlled by lithologic character, fracture, and structure. The local uplift in the vicinity of the hydrocarbon recession is most conducive to the collection of hydrocarbon gas.

Study of fault configuration related mysteries through multi seismic attribute analysis technique in Zamzama gas field area,southern Indus Basin,Pakistan

Seismic attribute analysis approach has been applied for the interpretation and identification of fault geometry of Zamzama Gas Field. Zamzama gas field area, which lies in the vicinity of Kirthar fold and thrust belt, Southern Indus Basin of Pakistan. The Zamzama fault and its related structure have been predicted by applying the Average Energy Attribute, Instantaneous Frequency Attribute, relative Acoustic Impedance Attribute and Chaotic Reflection Attribute on the seismic line GHPK98 A.34. The results have been confirmed by applying the spectral decomposition attribute on the same seismic line that reveal the geometric configuration of Zamzama structure. The fault is reverse and started from 0 s and ended at the depth of 2.5 s on the vertical seismic section. Hanging wall moves up along the fault plane under the action of eastward oriented stress, which formed a large northesouth oriented and eastward verging thrusted anticline.

Extrapolation for Aeroengine Gas Path Faults with SVM Bases on Genetic Algorithm

Mining aeroengine operational data and developing fault diagnosis models for aeroengines are to avoid running aeroengines under undesired conditions.Because of the complexity of working environment and faults of aeroengines,it is unavoidable that the monitored parameters vary widely and possess larger noise levels.This paper reports the extrapolation of a diagnosis model for 20 gas path faults of a double-spool turbofan civil aeroengine.By applying support vector machine(SVM)algorithm together with genetic algorithm(GA),the fault diagnosis model is obtained from the training set that was based on the deviations of the monitored parameters superimposed with the noise level of 10%.The SVM model(C=24.7034;γ=179.835)was extrapolated for the samples whose noise levels were larger than 10%.The accuracies of extrapolation for samples with the noise levels of 20%and 30%are 97%and 94%,respectively.Compared with the models reported on the same faults,the extrapolation results of the GASVM model are accurate.

Gas Path Fault Tolerant Control of Aero-Engine Based on On-Board Model

A fault tolerant control method is proposed in this paper for a turbofan engine gas path degradation through the full flight envelope. A Quantum-behaved Particle Swarm Optimization(QPSO) algorithm is applied to obtain engine inputs adjustments, which contribute to construct off-line performance accommodation interpolation schedules. With a double closed-loop control system structure, command control is corrected based on real-time fault diagnostic results. Simulations indicate that fault tolerant control could reduce thrust and stall margin loss effectively in gas path faults.

The Influencing Factors of Escaped Radon from the Jiayuguan Fault Zone and Its Earthquake Reflecting Effect

The paper analyzes the radon data of nearly two decades on the Jiayuguan fault zone,discusses the main influencing factors,and puts forward the relationship between radon and air temperature,ground temperature and rainfall.We summarized the earthquake reflecting effect for ML≥5.0 about 400km within the Jiayuguan station,and reached the conclusion that it has better earthquake-reflecting ability before an earthquake,usually appearing as abnormal changes in sustained low value.By extracting the annual trend of radon in Jiayuguan station over many years,we discovered that the annual trend of radon has a close relationship with the seismic activity in surrounding areas,namely,if the annual variation of radon is larger,the seismic activity in surrounding areas is stronger;Otherwise,if the annual variation of radon is relatively stable,the seismic activity in the vicinity is weak.

Hybrid Fault Diagnosis and Isolation for Component and Sensor of APU in a Distributed Control System

This paper addresses the gas path component and sensor fault diagnosis and isolation(FDI) for the auxiliary power unit(APU). A nonlinear dynamic model and a distributed state estimator are combined for the distributed control system. The distributed extended Kalman filter(DEKF)is served as a state estimator,which is utilized to estimate the gas path components’ flow capacity. The DEKF includes one main filter and five sub-filter groups related to five sensors of APU and each sub-filter yields local state flow capacity. The main filter collects and fuses the local state information,and then the state estimations are feedback to the sub-filters. The packet loss model is introduced in the DEKF algorithm in the APU distributed control architecture. FDI strategy with a performance index named weight sum of squared residuals(WSSR) is designed and used to identify the APU sensor fault by removing one sub-filter each time. The very sensor fault occurs as its performance index WSSR is different from the remaining sub-filter combinations. And the estimated value of the soft redundancy replaces the fault sensor measurement to isolate the fault measurement. It is worth noting that the proposed approach serves for not only the sensor failure but also the hybrid fault issue of APU gas path components and sensors. The simulation and comparison are systematically carried out by using the APU test data,and the superiority of the proposed methodology is verified.