Fine Description Of Low Level Faults Using Seismic Technique

Fractured reservoirs have the following characteristics: complex lithology, various types, severe-changing physical property and heterogeneity. So it is more difficult to achieve fine descriptions of fractured reservoirs, and the uncertainty of reservoirs is more obvious.Faults play an important part in hydrocarbon generation, migration and preservation of oil and gas. The identification and fine description technique of the low level faults is beneficial for arranging development well reasonably, getting the relationship between oil, gas and water. It is also helpful for enhancing oil recovery. With the improvement of exploration, exploration will serve development better and we should improve overall efficiency of exploration and development urgently. In that case, the identification and fine description technique to the low level faults that has been neglected is being taken increasingly seriously. This paper expound that the most part of China’s O il Field including Sheng Li O il Field come into the late stage of development. Therefore, the studies of various structural analyses which may be helpful to find residual hydrocarbon become more and more important. The shattered fault zone and the low- grade fault are accurately meet specifications. However, currently simple methods of geological research are unable to adapt to the requirements of exploration methods which used in the late stage of development. The interpretation of seismic profiles, the coherence cube technique and curvature attributes are becoming the key technologies to identify and describe the low-grade fault.According to the literature investigation, the paper provides a study idea of the low level faults and then introduces four kinds of low level faults description techniques. Finally, some real examples are applied and analyzed. The research shows: 1) Coherent data volume is an essential interpretation technique to the description of fractured reservoirs. Both the resolution and anti- noise ability of the coherent data volume based on calculating eigenvalue are better than conventional coherent cube. We can get the overall distribution of faults through it. 2) Curvature attribute is one of the most effective identification techniques of the low level faults. The application effect of dip, strike and the most-positive curvature is best among all curvature attributes. They can reflect shattered fault zones and low level faults very well. We also propose an algorithm for computing 3D volumetric curvature. The result demonstrates that it can describe the low level faults better. In seismic fracture characterization, curvature gradient as a new derivative attribute complements the existing curvature in the description of bed morphology. In certain cases where bed geometry is caused by structural bending and shearing, integrating curvature and curvature gradient attributes helps describe the low level faults. 3) Using the idea of seeds moving algorithm and its application on bridge crack detection for reference, we propose the procedure of seeds moving algorithm’s application on description of the low level faults at the first time. This algorithm and ant colony algorithm, as digital image processing technologies, lead to a good result.