二连盆地乌兰花凹陷安山岩岩相展布及储层预测

Lithofacies distribution and reservoir prediction of andesite in Wulanhua Sag,Erlian Basin

二连盆地乌兰花凹陷发育的安山岩油气藏勘探取得了重大突破,但安山岩储层非均质性强,储层预测难,其空间展布难以精细刻画,是制约该类油气藏勘探的关键。从研究区安山岩储层形成的地质成因分析入手,通过地震地质综合解释,岩心、测井及地震属性分析等技术手段,对安山岩岩相展布特征及有效储层预测方法进行了综合研究。结果发现,火山口主要位于控盆(控沉积)断裂带上,呈串珠状展布,推测当时火山呈裂隙式或中心-裂隙式喷发(源控);根据安山岩气孔发育程度,将研究区安山岩岩相划分为近火山口相、中火山口相和远火山口相,明确了研究区不同岩相的平面展布(相控);在此基础上,提出了在相控建模基础上去除低频背景的地震反演技术,明确了安山岩有效储层的平面展布。研究表明:乌兰花凹陷安山岩中火山口相为气孔最为发育的有利岩相,有效储层主要沿盆内NE向断裂带呈带状展布,其预测结果与已钻井相吻合。该研究为安山岩有效储层的预测提供了新的思路和方法,对类似地区火山岩油气藏的储层研究具有借鉴意义。

A major breakthrough has been made in the exploration of andesite reservoirs developed in Wulanhua Sag of Erlian Basin.However,the andesite reservoir is characterized by strong heterogeneity,difficult reservoir prediction,and difficulty in fine description spatial distribution,which restricts the exploration of this kind of reservoir.Based on the analysis of geological genesis of andesite reservoir formation in the study area,the distribution characteristics of andesite lithofacies and effective reservoir prediction methods were comprehensively studied by means of seismic and geological interpretation,core,logging and seismic attribute analysis.The results show that the crater is mainly located on the basin-controlling(sedimentary)fault zone,with beaded-like distribution.It is speculated that the volcano was erupted in the form of fissure or center-fissure(source-controlling).According to the degree of stomatal development of andesite,the andesite facies in the study area was divided into near crater facies,middle crater facies and far crater facies,and the plane distribution(facies control)of different lithofacies in the study area was defined.On this basis,a seismic inversion technique based on phased-controlled modeling was proposed to remove low-frequency backgrounds,and the effective andesite reservoir distribution was defined.The results show that the middle crater facies is the most favorable facies for stomata development in andesite,the effective andesite reservoirs are mainly distributed along the NE-trending fault belt,and the predicted results are consistent with the drilled wells.This study provides a new idea and method for the prediction of effective andesite reservoirs,and is of great significance for the study of volcanic reservoirs in similar areas.