The Fractal Study Of Fault System And The Distributing Of Hydrocarbon In The Nanpu Sag, Jidong

The relation of fault and hydrocarbon, a hotspot and nodus, always has been noticing by expert in the field of petroleum geology. Reason is two sides of antinomy, one side is that fault play a relative important role in the progress of hydrocarbon reservoir formation, another is that ways used to study faults is very poor, especially quantificational. With use of fractal theory in the field of geology, the ways of studying fault have stridden on the road of quantification.Jidong, Nanpu sag, locating in the northeastern North China platform, on southern margin of Yanshan platformal fold belt, is a little depression formed in the tertiary in the northern Bohaiwan basin. The directions of fault extend are mainly NE and NW. Two team faults are cut each other, which lead to the complex condition of geology and enhance the difficulty of exploration and exploitation. But the practice of exploration indicated that fault belts were important site where oil and gas was assembled preferentially. So the quantificational study of fault belts in the nanpu sag is very important.In this paper, the fractal theory is used at each map of faults at the bottom of stratum above the Dongying formation, the scale of each map is 1 to 100000. Each map is divided into some square that side is forty centimeter. In the each square, I have tested fault self-similarity in space. Correlation coefficients is from 0.98 to 1, which indicate that the fault possess fractal structure. Then the fractal dimension of capacity of fault in the each square is calculated and is put at the center of its square. Adopting software named SUFFER, the isogram of fractal dimension of fault at the bottom of each stratum above the Dongying formation is portrayed. The following are two conclusions from the isogram of fractal dimension.Which can be known from the isogram of fractal dimension of fault at the bottom of Minghuazhen formation, the three of four oilfield are located in the areas where the fractal dimension of capacity are larger than 1.18, which show that the distribution of the fractal dimension relates to the distribution of oilfield. So Beipuxi fault zone, nanpu fault zone, laopu fault zone and Getuo fault zone are ascertained as the favorable areas.Which can be known from the each isogram of fractal dimension of fault, faults play a very important role in the progress of forming reservoir of oil and gas. They have been working as a kind of routeway which permit oil and gas to pass from down to up. At the same time, some faults have been preventing oil and gas to diffuse availably, which form trap about fault. So we know more distinctly that fault zones are favorable areas for exploration.In addition, multifractal theory also is used to analyze the relation of faults and the distribution of oilfields, self-similarity of fault has been examined by using multifractal theory according to map of faults distribution in the bottom of Minghuazhen formation of Nanpu sag. Correlation coefficients are better than 0.99, which suggests that faults are fractal structure. The paper has not only calculated multifractal dimensions of Nanpu sag and its five tectonic zones but also limited the range of multifractal dimensions (D₀: 1.68—1.84,D1: 1.57—1.76, D2: 1.45— 1.73). Because multifractal dimensions of Nanpu fault zone, Beipuxi fault zone, Laopu fault zone...