THE PRINCIPAL STRESS ORIENTATIONS BY THE BOREHOLE BREAKOUTS IN HUANGHUA DEPRESSION

We discuss the characteristics, the principles of identification and the measuring method of the borehole breakouts in this paper. Based on the borehole breakouts analysis of 32 oil-wells with two different records of four-arm dipmeter log of Schumberger and dipmeter log of Delasy-Atalas, using the Stereonet program to process several thousand groups of data, it is obtained that the regional mean orientations of maximum horizontal principal stress is N70°-80°E in Huanghua Depression, while the local ones is in Zaoyuan oil field which is located in the southern portion of Huanghua Depression. The results indicate that the NNE horizontal compressional stress field in Huanghua Depression is in a good agreement with the right-lateral strike-slip NNE-NEE trending faults in Huanghua Depression, but in Zaoyuan oil field the orientations of maximum horizontal principal stress deviates 20° 30°to the noeth under the influence of Fenghuadian structures, which shows that the local modern.structures control the local modern tectonic stress field in Zaoyuan oil field.