泥页岩储层裂缝特征及其与“五性”之间的关系

Relationship between fracture characteristics and “five-property”of shale reservoir

泥页岩地层通常具有低孔、低渗特征,存在裂缝及裂缝发育程度均是其能够成为储层的决定性条件。以苏北盆地阜宁组泥页岩地层为研究对象,研究裂缝特征及其与岩性、物性、含油性、电性及可压裂性("五性")之间的关系。结果表明:裂缝普遍含油,发育裂隙的样品渗透率明显较高,一般都大于10 m D,裂缝对改善泥页岩地层的渗透性及储集性起到了重要作用;含裂隙样品通常脆性矿物(方解石)含量较高,对应的岩性一般为灰质泥岩、含灰页岩及含灰泥岩;天然裂隙发育的层段杨氏模量较高、泊松比较低、脆性系数较高,页岩的脆性较强,通常易于压裂改造。利用测井响应特征可明显区分方解石充填裂缝和有油迹显示的无充填裂缝,可为识别有效泥页岩储层提供依据。

Shale formations are typically characterized by condition of whether shale formations can be reservoirs is low porosity and low permeability. While, the decisive nothing but the existence and development of fracture. Taking shale formations of Funing Formation in Subei Basin as an example, this paper studied the relations of fracture characteristics with lithology, physical properties, oiliness, fracability and electric properties. During the research, petroliferous fractures are easy to found, and it is obvious that the permeability of fractured sample is higher than that of uncracked, which is greater than 10 mD in general. Fracture plays an important role in improving shale permeability and reservoir capabilities. Samples with fractures usually have higher content of calcite and the corresponding lithology is generally calcareous mudstone, limy shale and limy mudstone. The intervals which developed intrinsic fracture have high Young＇ s modulus, low Poisson＇ s ratio and high brittleness coefficient. The intervals＇ brittleness is strong, and for this reason, these intervals are normally easy fracturing. Using logging response characteristics can easily distinguish fractures with calcite filled and no filling cracks accompany with oil trace. This result provides a basis for identifying effective shale reservoir.