鄂尔多斯盆地合水地区长8 段裂缝发育 特征及其对产油量的影响

在岩心观察和电成像测井资料分析的基础上,对鄂尔多斯盆地合水地区长8段裂缝的产状、高度和发育位置进行了统计分析,总结出合水地区长8段裂缝平面分布规律,依据裂缝线密度平面分布特征,将合水地区划分为强裂缝发育区、裂缝发育区、弱裂缝发育区和裂缝不发育区。合水地区长8段裂缝主要分布在粉砂岩和泥岩中,其次分布在细砂岩中。储层物性越好,裂缝越不易发育;同一岩性,岩层厚度越大,裂缝越不发育。长8段强裂缝发育区和裂缝发育区的储层物性均较差,厚度较小,油井产量不高,而在弱裂缝发育区往往有高产油井。这进一步说明,如果储层本身的物性和含油性较差,即使有裂缝发育,也难以获得工业油流;储层围岩裂缝的存在对压裂效果和含油层段产量影响不大,产油量的主控因素是储层本身的岩性、厚度、物性和含油性。

The study of relationship between fracture characteristic and yield of Chang8 section in Heshui area, Ordos Basin

Based on observation of core and analyses of logging data, fracture occurrence, height, position are analyzed in Chang8 section, Heshui area. The fracture planar distribution was summarized. According to the fracture linear density, Heshui area is divided into strong fractured zone, fracture developed zone, weak fractured zone and non-fractured zone. Fracture in Chang8 section is mainly distributed in the siltstone, followed by fine sandstone and mudstone. The better the porosity and permeability of reservoir are, the less the fracture develops. For layers of the same lithology, the greater the thickness of layer is, the less the fracture develops. In the strong fractured zone and the fracture developed zone, the porosity and permeability are poor and the layer thickness is small. So oil production is not high in the two zones, and high yield wells are always in the weak fractured zone. This shows that it is difficult to obtain industrial oil flow even if the reservoir is fractured when its porosity and permeability and oil bearing are poor. Fracture existed in the formation nearby reservoir has little effect on fracturing and the yield of oil-bearing reservoir. Controlling factors of oil production are lithology,thickness, physical properties, oil bearing of reservoir.