公山庙沙一段油气藏低孔渗储层产油机理研究

STUDY OF OIL PRODUCING MECHANISM FOR RESERVOIRS WITH LOW POROSITY AND PERMEABILITY

四川盆地中部公山庙沙一段油藏为构造岩性复合油藏 ,单井测试日产原油在数吨至百吨之间。储层具典型的低孔渗特征 ,产层段孔隙度一般在 3%～ 6 % ,平均 3.9% ;渗透率在 1.0× 10 -4μm2 ～ 1.0× 10 -3 μm2 ,平均2 .6 4× 10 -4μm2 。文章在静态、动态分析的基础上 ,应用核磁共振、水膜实验、渗流能力模拟及岩心产能模拟等机理实验研究表明尽管储层基质物性为低孔低渗 ,但其仍具备储渗能力 ,储渗类型为裂缝—孔隙型。并在此基础上结合地层能量以及原油性质综合研究认为低孔渗储层基质产油有以下主要原因 :①孔隙结构好的储层为油流提供了较好的储渗体系 :②充足的地层能量为原油渗流提供了动力基础 ;③以小分子为主的低粘度、低密度优质油有助于原油的渗流。较好的解释了该油藏低孔渗储层产油的机理 ,对以低孔渗储层为主的四川盆地砂岩油气藏勘探具有重要指导意义。

Section Sa 1 reservoir is a litho-structural oil pool. According to testing, the production from a single well reached between several tons and more than 100 tons. The reservoir is characterized as low porosity and permeability typically: The porosities of the producing intervals various from 3% to 6%, averaging 3.9%. The permeability varies from 1.0 × 10-4 μm2 to 1.0 × 10-3 μm2, average 2.64 × 10-4 μm2. Based on the static and dynamic analysis, using nuclear magnetic resonance, water membrane experiment, permeable ability modeling and core productivity modeling, etc. the article studied and verified the matrix of the reservoir belongs to the type of low porosity and permeability, but still has the accumulating and permeable ability caused by fractures and pores. Integrating the formation energy and the crude oil property, the study shows the following reasons why the matrix with low porosity and permeability can produce oil: 1 The reservoir with good pore configuration provides the accumulating and permeable system for oil flowing. 2 The enough formation energy provides the power for oil flowing. 3 The light oil with low viscosity and density molecular is easy to flow. The results explain the oil producing mechanism of the reservoir with low porosity and permeability, and can guide oil & gas exploration for sand reservoirs with low porosity and permeability in Sichuan basin, even for the similar reservoirs in China.