孔隙空间分布规律对酸蚀蚓孔扩展规律的影响

酸蚀蚓孔发育扩展规律除了与注入条件、酸液类型、温度和岩石类型有关外,还与孔隙度大小和孔隙空间分布规律有关。本文研究了普光气田岩心孔隙空间分布规律对蚓孔扩展的影响。采用CT扫描岩心得到孔隙度的三维分布,分析孔隙空间分布规律,然后进行岩心酸化流动实验,得到蚓孔突破岩心需要的酸液孔隙体积倍数,实验完毕后再用CT扫描蚓孔形状。通过对比实验前的孔隙度分布和酸化后的蚓孔形状、分析岩心孔隙度和蚓孔突破岩心需要的酸液孔隙体积倍数间的关系,得到孔隙空间分布规律对蚓孔发育扩展的影响。研究发现,蚓孔趋于沿大孔道分布的地方扩展,蚓孔突破岩心需要的酸液孔隙体积倍数随孔隙度增加而降低,对于普光气田I和II类岩心,突破孔隙体积倍数高的约4,低的约0.4,大多在1左右,较致密的III类岩心在实验压差下没形成蚓孔。

Effects of Spatial Distribution of Pores on Wormhole Propagation

Wormhole propagation depends on porosity and spatial distribution of pores, in addition to flux, acid type, temperature, and mineralogy. In this paper we studied the effect of spatial distribution of pores on wormhole propagation in Puguang gas field. We used CT scan to obtain spatial distribution of pores of the cores, and then did core flooding by acid to obtained pore volume to breakthrough for wormholes (PVbt). After core flooding, used CT to get wormhole shape. By comparing spatial distribution of pores before acidizing with the shape of the wormholes and analyzing the relationship between porosity and pore volume to breakthrough, we found that, wormholes tend to propagate along the places where large pores lie. PVbt decreases with porosity increase. For the cores of category I and II in Puguang gas field, PVbt is up to 4, down to 0.4, and about 1 for most cases. For category III tight cores, no wormholes were obtained under given pressure drop.