塔河油田石炭系卡拉沙依组沉积与成因分析

Deposition and genetic analysis of Carboniferous Kalashayi Formation in Tahe oilfield

何发岐 翟晓先 俞仁连 蒲仁海

He Faqi Zhai Xiaoxian Yu Renlian Pu Renhai

综合古生物、测井、岩心、地震、地化等资料,对塔河油田石炭系卡拉沙依组砂泥岩段沉积特点及成因的分析表明该组砂岩总体具有向上变粗变厚的进积式沉积序列:上部的Ⅰ-Ⅲ油组主要为河流相,下部Ⅳ-Ⅴ油组为受潮汐影响的扇三角洲前缘和平原相。该组受潮汐影响体现在:(1)富含陆相轮藻化石,并见个别半咸水介形虫类和疑源类微体化石;(2)局部有波状、透镜状层理、生物扰动层理和冲刷充填层理;(3)该组底部泥岩的锶钡比值介于0.021～0.716,具半咸水-微咸水-淡水的变化特点;(4)Ⅳ-Ⅴ油组总体处于巴楚组双峰灰岩潮坪相到Ⅰ-Ⅲ油组河流相沉积的过渡相中。

Sedimentary characteristics and genesis of the Carboniferous Kalashayi Formation sand-shale sequence in Tahe oilfield are analyzed through integrating palaeontological,log,core,seismic and geochemical data.Overall,the sandstones in Kalashayi Formation are of progradational sedimentary sequence that get coarser and thicker upwards.The upper Ⅰ-Ⅲ oil reservoir groups are mainly of fluvial facies,while the lower Ⅳ-Ⅴ oil reservoir groups are of tide-effected fan delta front facies and plain facies.The evidences of tidal influences include:(1)rich in charophyta fossils with individual brackish Ostracoda and Acritarch microfossils;(2)local wavy,lenticular,bioturbate and scour-and-fill beddings;(3)a strontium/barium ratio ranging between 0.021 and 0.716,suggesting an environment from brackish to fresh water;(4)the Ⅳ-Ⅴ oil reservoir groups,as a whole,are the transition facies from tidal flat "double peak limestone" in the Bachu Formation to fluvial deposition of Ⅰ-Ⅲ reservoir groups.

10.11743/ogg20040304