塔里木盆地大宛齐油田康村组成岩作用及其控制因素

大宛齐油田是迄今为止在塔里木盆地发现的产层最浅的油田 ,主力产油层段为第四系和上第三系的康村组。通过岩心和薄片的观察、X衍射分析、扫描电镜分析等资料 ,对砂岩的岩石学特征进行了探讨 ,深入研究了储层的成岩作用及其控制因素。大宛齐地区康村组砂岩主要由一套不同粒级的岩屑砂岩组成 ,总体上砂岩的成分成熟度较低 ,结构成熟度也不高。主成岩作用是机械压实和胶结作用 ,成岩环境为略偏碱性—中性的干旱环境 ,埋藏深度浅 ,地温梯度较低 ,现今储层正处于早成岩阶段A亚期 ,孔隙度的演化也相应地可分为快速压实、孔隙度快速降低阶段和稳定压实、方解石胶结物快速增加阶段。控制成岩作用的主因素是储层的埋深、储层岩石成分等。

THE DIAGENETIC CHARACTERISTICS AND ITS CONTROLLING FACTORS OF THE KANGCUN FORMATION IN THE DAWANQI OILFIELD,THE TARIM BASIN

The Dawanqi oilfield is of the most shallow oil productive formation in the Tarim Basin, whose major oil productive formations locate in the Quarternary and the Kangcun Formation of Neogene. The petrologic characteristics and diagenesis of sandstone are discussed in this paper and the factors controlling diagenesis are also studied by means of core observing, thin sections investigating, X-ray diffraction analyzing and electron microscope scanning. Sandstones of the Kangcun formation are composed of a series of lithic sandstones with lower compositional maturity and textural maturity. The clastic components are of high content of debris, low content of quartz and feldspar: The main matrix is a small amount of terrigenous clay in common. The cement is simple and most of which is calcite. The texture of rocks is of bad sorting and of mainly sub-rounded to sub-angular roundness with the predominant porous cementation. There are two important diagenesis-compaction and cementation, moreover, the cementations are divided into the carbonate cementation, clay mineral cementation and siliceous cementation. Reservoirs of the Kangcun Formation are being in the stage A of early-diagenesis nowadays. The major factors controlling diagenesis are depth of reservoirs and composition of rocks.