鄂尔多斯盆地白豹油田长81储层水驱油特征及驱油效率影响因素

Water flooding characteristics and influencing factors of oil displacement efficiency of Chang 81 Reservoir in Baibao Oilfield,Ordos Basin

为了分析致密砂岩油藏内部油水运动规律及驱油效率影响因素,以鄂尔多斯盆地白豹油田长8_(1)储层为研究对象,利用物性分析、压汞实验、核磁共振实验、真实砂岩模型可视化渗流实验等方法,结合油田生产动态资料,研究储层微观水驱油特征及驱油效率影响因素。结果表明:长8_(1)储层水驱油渗流路径以均匀状、网状和指状为主,对应的驱油效率依次降低;水驱油特征主要受储层微观孔隙结构、物性、可动流体饱和度等地质因素,以及驱替压力、驱替速度等开发因素共同影响。微观孔隙结构决定水驱油的渗流路径,喉道半径、孔喉分选系数、孔喉半径比与驱油效率具有较好的相关关系;储层品质因子能更好地表征储层储渗性能,影响驱油效率;可动流体饱和度反映有效储集空间与盲孔、无效孔隙的相对含量比,在较低可动流体饱和度条件下,对驱油效率的影响更为明显。当喉道半径≤0.8μm、储层品质因子≤0.25、可动流体饱和度≤50%、驱替压力增幅≤50%、驱替速度≤0.012 mL/min时,对水驱油特征及驱油效率影响明显,实验条件下的水驱油特征影响油田开发效果。该结果为鄂尔多斯盆地白豹油田长81油藏的高效开发提供依据。

In order to reveal the rule of oil-water movement in tight sandstone reservoir and the influencing factors of oil displacement efficiency,the Chang 8_(1)Reservoir of Baibao Oilfield in Ordos Basin is taken as an example to study the micro water displacement characteristics of reservoir and the influencing factors of oil displacement efficiency by means of physical property analysis,mercury injection,nuclear magnetic resonance,real sandstone model water displacement experiment and other experimental methods,combined with oilfield production dynamic data,the characteristics of micro water flooding and the influencing factors of oil flooding efficiency are studied.The results show that the seepage paths of water flooding in Chang 8_(1)Reservoir are mainly uniform,net and finger,and the corresponding oil displacement efficiency decreases in turn.The characteristics of water flooding are mainly affected by geological factors such as reservoir micro pore structure,physical property,movable fluid saturation and development factors such as displacement pressure and displacement speed.The micro pore structure determines the seepage path of water flooding,and the throat radius,pore throat separation coefficient,pore throat radius ratio have a good correlation with oil displacement efficiency.The reservoir quality factor can better represent the reservoir permeability and has a certain impact on the oil displacement efficiency.Movable fluid saturation reflects the relative content ratio of effective reservoir space to blind and ineffective pores.It is an important index to measure the effective flow of a reservoir and one of the factors affecting the oil displacement efficiency.When throat radius is less than 0.8 μm,reservoir quality factor is less than 0.25,movable fluid saturation is less than 50%,displacement pressure increase is less than 50%,and displacement speed is less than 0.012 mL/min,the water drive oil characteristics and displacement efficiency are obviously affected by the above factors.The water drive oil characteristics under experimental conditions respond well to the oilfield developmenl effect.The research results provide a basis for the efficient developmenl of Chang 8_(1)Reservoir in Baibao Oilfield.