毛细管理论在低阻油气层油气运移与聚集机理中的应用

根据油气在地层中的势和所受到的力理论,认为油气在运移与聚集过程中的主要驱动力为重力和围水压力变化引起的力,而毛细管压力则主要起阻力作用.毛细管压力与储层的孔喉结构、排替压力和油气可进入的孔喉多少有直接关系,所以它对油气的运移与聚集起着关键性的作用;根据毛细管理论,依据油气在低电阻率储层中运移和聚集的特点,阐述低电阻率油气层的形成机理.由于毛细管压力的作用,如果距离油源较远、油气源中的油气不丰富、储层岩性细、孔隙结构复杂、垂向上物性好的储集层发育较多或单层储集空间足够大等均会导致低电阻率储层中的微中、小孔隙中的水无法排出,致使储层不动水含量过高,从而显示油气层的低电阻率特征,即高含水饱和度是引起油气层电阻率较低的主要原因之一.

Application of Capillary Theory in the Migration and Accumulation Mechanism of Oil/gas in Low-resistivity Zone

The potential and force theory reveals that gravity and the forces caused by the grounding water are the main driving forces, and capillary pressure is the main resistance force in the process of the migration and accumulation of oil/gas. Because the capillary pressure is directly related to the pore structure, displacement pressure and the pore number that oil/gas can enter, it plays the key function in the migration and accumulation of oil/gas. According to the capillary theory and the characteristic of the migration and accumulation of oil/gas in the low resistivity reservoirs, expatiated is the formation mechanism of the low resistivity reservoirs. Because of the function of the capillary pressure, phenomena such as reservoirs far from the oil/gas sources, fine lithologic reservoirs, complicated pore structures, huge storage capacity in single reservoir and amounts of vertically developed reservoirs, may cause the formation water not to be replaced by oil/gas in the middle and small pores in low resistivity reservoirs so that the water saturation is higher, and the reservoirs have the lower resistivity characteristics, that is, high water saturation results in low resistivity reservoirs.