Design Study Of Offshore Oil And Gas Exploration And Instrument Parameters

Oil is honored blood of modern industry development. The requirement on oil grows together with the rapid development of Chinese economy. Now that the exploitation of China inland oil fields has entered its middle stage, while the offshore strips and deep sees are abundant in oil and gas, how to exploit these offshore resources has becoming more important and urgent. 863, the National Hi-tech Research and Development Program, began in 2001 a project of research on development of offshore oil resource exploration equipments, with Chinese self-owned intellectual authority. Our lab is responsible for research and development of the Time-lapse Marine Seismic Data Acquisition and Recording System (TMSDARS). During the years of development, we realized that there are far more things in exploration than developing electronics devices and user interface. The parameters of equipment should fit the real crust structure. Because offshore oil exploration costs a huge amount of money and time, pre-exploration parameters design and on-line re-adjustment are quite essential. However, currently our equipment has no offshore exploration pre-exploration plan software, and the user interface program has no on-line data processing functions. This thesis is based on the above background, focuses on offshore seismic data processing and equipment parameters design.The pre-exploration plan and on-line re-adjustment have many common points. Both require knowledge on geologic model and offshore oil exploration process, which will be discussed first. The relationships between equipment parameters and exploration resolution are then demonstrated. After introducing basic offshore seismic data processing procedures and the special designed anti-noise techniques, the feasibility and choice in on-line data processing is discussed. At last, an implement is given, showing how to integrate the theories and algorithms into the user interface of TMSDARS and single cable checking system. This thesis is composed of seven chapters, whose abstracts are listed below.Chap 0 - Brief Description of the Whole ThesisThis chapter introduces the soul of this thesis. It begins with the background and reasons for the research, then introduces the works that have already been done and its corresponding significance, at last points out possible directions of future research.Chap 1- Introduction to offshore seismic explorationThis chapter starts with the background of oil yield and consumption worldwide, especially that of China, then introduce the procedures used in offshore seismic exploration, e.g. data gathering, signal processing, and interpretation. The key idea of exploration is to generate a short wave pulse, then convert water pressure distribution within the next few seconds into digital data. Because different rock layout structure leads to reflections different in time and amplitude, from the digital data rock layout structure can be deduced, and geophysical experts will check out the possibility and capacitance of oil resource. At last, the main purpose and meanings of this thesis are pointed out.Chap 2 - physical models of offshore seismic explorationThis chapter starts with Wave Equation of sound in water and solid rock, then simplifies them because in water exists no P-Wave. The sensor offset and reflection arrive time forms a hyperbolic equation for a single interface reflection. If equivalent velocity is considered, this equation can be extended to fit multi-interfaces reflections. At last, the method of forward modeling, which deduces pressure distribution from possible terrane structure, and the method inversion, which deduces structure from distribution, are briefly introduced.Chap 3 - requirements on seismic exploration parametersThis chapter starts with the resolution definition of seismic exploration, including vertical resolution and horizontal resolution, which ultimately base on the size of the smallest visible structure, then introduces the parameters of seismic exploration equipments, including the air-gun array signal, physical model of hydrophone, the frequency and phase response of A/D and the following FIR/IIR filter, sample rate, signal noise rate, measuring range, near offset and far offset of hydrophone matrix, shot interval and record time length. Real parameters of TMSDARS and other exploration equipments that are used in offshore experiment 2005 are given out. At last, the relationship between equipment parameters and the resolution are discussed, respectively in vertical and horizontal directions.Chap 4 - Draw equipment parameters related information from seismic dataThis chapter first discusses the fundamental seismic data processing work-flow, then focus on how to draw information from seismic data. Frequency analyse and filterring, F-K analyse and filterring and used to check the characters of reflection. Velocity and thickness of each stratum are calculated. Noise and anti-noise methods are discussed. The data processing methods in Chap 4 and 5 are based on the real seismic data that are obtained using TMSDARS on November, 2005, on South-China Sea.Chap 5 - parameters plan and adjust software designThis chapter first lists out three offshore seismic exploration systems developed or to be develped by China, e.g. TMSDARS, Single Cable Checking System and Deep-sea High Resolution Seismic Data Acquisition and Record System. Then discussed the possibility of embedding various algorithms introduced in Chapter 3 and 4 into the software of these systems. At last, the details of software structure are designed, including user interface, core algorithms design, log and result report.Chap 6 - conclutions and the futureThis chapter compares the parameter of Chinese self-developed systems and foreign ones, concludes the original ideas of this thesis, introduces my work in corresponding projects, and points out possible direction of future amendment.