哈得4CⅢ油藏隔夹层控制倾斜油水界面成因数值模拟

哈得4CⅢ油藏为边底水海相砂岩油藏,存在高差近100 m的大幅度倾斜油水界面,其成藏机理和倾斜油水界面成因尚存争议。根据该油藏储集层、流体和隔夹层特征,建立相应的地质模型,通过调整隔夹层的数量、分布范围、毛细管压力、天窗数量等,模拟该油藏油气二次运移成藏过程。隔夹层数量及分布对倾斜油水界面的形成和油水分布有明显影响;隔夹层毛细管压力越大,油水界面倾斜幅度越大;隔夹层延伸长度越大,油水界面倾斜幅度越大;隔夹层天窗数量和位置不同,油藏成藏期末油水分布和油水界面也明显不同。该油藏油水界面大幅度倾斜成因主要是隔夹层遮挡作用和成藏过程中油水重力分异作用,其次为构造运动和非稳态成藏作用。

Numerical Simulation on Tilted OWC Controlled by Interlayers in Hade 4CⅢ Reservoir

The Hade 4CⅢreservoir is a marine sandstone reservoir with edge and bottom water, where there is a largely-tilted oil-water contact (OWC) with a height difference of nearly 100 m. The hydrocarbon accumulation mechanism and the origin of the tilted OWC are still controversial. According to the characteristics of beds, fluid and interlayers in the reservoir, a corresponding geological model was established. By adjusting the number, distribution, capillary pressure, and skylights of the interlayers, the process of secondary migration and accumulation of oil and gas in the reservoir was numerically simulated. The number and distribution of the interlayers have a significant impact on the formation of the tilted OWC and on the distribution of oil and water. The higher the capillary pressure of the interlayer, the greater the inclination of the tilted OWC. The longer the extension of the interlayer, the greater the inclination of the tilted OWC. If the number and location of interlayer skylights are different, the oil-water distribution and oil-water contact are also significantly different at the end of the hydrocarbon accumulation period. The great inclination of the tilted OWC in the Hade 4CⅢreservoir is mainly due to the shielding of interlayers and the differentiation of oil-water gravity during the hydrocarbon accumulation, followed by tectonic movement and unsteady hydrocarbon accumulation.