松辽盆地头台油田现代地应力场分布特征研究

Variation of Modern Reservoir Stress Field in Toutai Oilfield, Songliao Basin

在油气田开发 ,尤其是低渗透油田的开发过程中 ,井网布局与地应力的分布紧密相关。运用现场直接测量、岩芯观察、室内实验、数值模拟相结合的方法 ,对头台油田现代地应力分布特征进行的详细研究表明 :头台油田水平最大主应力 (人工裂缝 )方向为N10 0°～ 12 0°E ;天然裂缝方向在N0°～ 50°E之间 ;地层中三向应力为南部较小 ,北部较大 ,构造断裂与天然裂缝的走向近似平行。因此 ,井网布局为 :井排与人工裂缝及天然裂缝呈 4 5° ,30 0m× 30 0m切割注水井网 ;注水压力应小于最小主应力值 ,采用不稳定间歇注水。

Reservoir stress is caused by both gravity and tectonic movements. The well pattern for oil-and-gas development is considerably constrained by distribution of reservoir stress, particularly in the reservoirs with low permeability. In this paper, we will prensent the results of an investigation on the distribution pattern of modern reservoir stress of the Toutai Oilfield based upon in situ measurements, core observations, laboratory work and numerical simulation. The maximum principal stress (artificial fracture) in the horizontal plan of the Toutai Oilfield is directed N100°～120°E with a mean of N110°E, and the natural fracture between N0°～50°E. The southern part of the oil field has smaller reservoir stresses in three directions than the northern part. The direction of structural faults is almost parallel to that of natural fractures. Therefore, a reasonable well pattern cutting the waterflood well pattern should be designed to be 300m×300m and at 45° to artificial and natural fractures. Waterflood pressure should be smaller than the minimum principal stress, and the technique of unstable intermittent waterflooding should be adopted.