塔里木盆地东河1油藏低渗层层序控制特征及其对注气开发的影响

摘要

Logging data and core analysis show that the Donghe sandstone of Donghe1 reservoir in Tarim Basin consists of foreshore, upper shoreface and lower shoreface facies zone from the bottom upward, and can be further divided into 11 parasequences. Accord⁃ing to petrographic analysis, the low-permeability layers in this sandstone can be classified into three categories:calcareous cementa⁃tion low-permeability layers, matrix low-permeability layers and mixed low-permeability layers. The calcareous cementation low-permeability layers are cemented by calcite, siderite, and ferrodolomite mainly distributed within the parasequences and are controlled by diagenesis. The distribution of matrix low-permeability layers are characterized by the lag deposits during transgression, and are controlled by parasequence boundaries. There are a number of mixed low-permeability layers distributed either in the parasequences or along the sequence boundaries, within which the intergranular pores are filled with both matrix and calcite cements. In combina⁃tion with the pressure data, the parasequence boundary-controlled matrix low-permeability layers extend widely and have obvious impact on gas-injection.%通过测井和岩心分析，将塔里木东河1油藏东河砂岩段从下到上划分为前滨-上临滨-下临滨相带，并进一步划分出11个准层序。经岩相学分析，将砂岩段低渗层分为钙质胶结低渗层、杂基充填低渗层和混合低渗层。钙质胶结低渗层主要分布在准层序内部，以方解石胶结砂岩为主，受成岩作用控制；杂基充填低渗层主要分布在准层序边界处，多为海侵背景下的滞后沉积产物；混合低渗层在准层序内部及边界均有分布，但数量很少，无明显规律性，砂粒间主要由杂基和方解石胶结物混合充填，充填物含量低。结合测压资料认为，发育在准层序边界处的杂基低渗层保留了更多的初始沉积特征，易形成横向连续性好的低渗层，是注气开发的重点关注对象。