松辽盆地三肇地区油田储层裂缝及地应力特征

在大量裂缝发育特征的观察和统计工作基础上，结合油田开发动态和古构造发育史分析等，应用岩芯古地磁定向，差应变和波速各和异性等研究方法，结果认为三肇地区扶杨油层发育的裂缝走向以近东西向为主，多具高倾角，并可构成规模较大的主裂缝，其在油田注水开发中起着不可轻视的作用。分析表明，裂缝发育的密度与砂层的厚度成反比，与构造曲率成正比。区域最大水平主应力为北西西向，近东西向裂缝为油田最有效裂缝组系。

STUDY ON FRACTURES AND THEIR STRESS FEATURES IN OIL RESERVOIR OF THE SANZHAO DISTRICT, SONGLIAO BASIN

Located in the eastern Daqing placanticline, north part of the Songliao basin, the Sanzhao district is the most important peripheral oil accumulation area of Daqing oilfield. Since the Fuyang reservoirs are the main oil bearing formations in this area and characterized by poor physical properties and low production, further studies on the reservoir fractures, as well as their effects in the modern stress field would be necessary for the efficient development and high stable production of Daqing oilfield. Aimed to solve some urgent problems for the development of oilfield, such as the well water out and production decrease caused by abundant fractures in the reservoirs, a comprehensive study has been conducted to investigate the properties and pattern of distribution of fractures in the Fuyang reservoir. Results of this study are summarized as the followings: (1) Natural fractures in the Sanzhao region are primarily oriented in near EW, NS and NE directions. Although the dominant fractures may vary both vertically and horizontally in different oilfields, most fractures are oriented approximately in EW direction. (2) Most fractures in the Fuyang reservoirs are shear fractures with high dip angle. A close correlation has been found between the filling degree of fractures and the oil bearing rank of sandbody. High oil bearing rank is usually associated with the less filled fractures. (3) Quantitative study has suggested that the fracture density and the thickness of rocks is related to esch other. The thicker the rocks, the lesser the fractures. (4) For the Fuyang reservoirs in the Sanzhao district, the largest horizontal major stress has an approximate EW direction and natural fractures in EW direction are effective fractures.