安棚油田深层系水平主应力方向及其对开发的影响

在泌阳凹陷安棚油田深层系低渗透油藏中,对地层水平最大主应力方向认识上一直存有争议。根据岩心观察和定向取心资料认为:该深层系储集层天然裂缝较发育,为两组呈“x”相交的裂缝,一组走向为20~40°,另一组为80~100°,力学性质为剪性或张剪性,并据此推断裂缝形成时水平最大主应力方向为北东60°左右。由于布井时受地层水平最大主应力方向为东西观点的影响,目前深层系水平最大主应力方向已成为注入水单向突进的方向,造成油井水淹加速。因此,提出调整措施:通过油井转注或补打新的水井将原来东西向的注水井排调整为北东向的注水井排,抑制含水上升速度,提高注水波及体积系数,以改善开发效果。

The Horizontal Principal-Stress Orientation and Its Effect on Development of Low Permeability Reservoir of Paleogene in Anpeng Oilfield

The maximum horizontal principal-stress orientation of Paleogene low permeability reservoir of Anpeng oilfield in Biyang sag is in dispute. The available core observation and orientational coring data indicate that there exist crossed two-group natural fractures in this reservoir, one trend ranges from 20°to 40°, the other trend from 80°to100°, with shear or extension-shear mechanical property. It is inferred that the maximum horizontal principal-stress orientation of the fractures when formed was about N60°E. But affected by the idea of being EW trend of the orientation, the present maximum principal-stress orientation has become the direction of injected water breakthrough, causing quickly raising of water cut in production wells. This paper presents the measures for improving the waterflood sweep efficiency as follows: converting production well to injection well or adding new wells allow the original EW array of water injection wells to become NE one.