准噶尔盆地莫索湾凸起石炭系上部岩性预测

准噶尔盆地莫索湾凸起深层石炭系存在特大型背斜圈闭,石炭系上部是否存在火山岩是莫索湾凸起深层油气勘探成功的关键。莫索湾凸起与相邻地区石炭系油气藏特征的对比研究发现,火山岩与沉积岩在磁力异常、地震相特征方面具有较大的差别,位于莫索湾凸起高部位的莫深1井区磁力异常特征与相邻的石西凸起火山岩油气田具有相似性,处于强—弱磁力异常之间的过渡带,接近中酸性火山岩磁力异常特征。地震相分析表明,莫索湾凸起大部分地区以强振幅反射为主,弱振幅反射主要分布在莫索湾凸起东南凹陷区。综合磁力异常与地震相特征,推测莫索湾凸起石炭系上部岩相特征为:凸起中部为中酸性火山岩夹沉积岩相分布区,凸起西南翼和东北翼为中基性火山岩分布区,凸起东南翼(芳2井区)和东道海子凹陷中南部及陆南1井区为沉积岩分布区。莫索湾凸起石炭系火山岩储层后期改造具有4个有利条件,推测莫索湾凸起石炭系火山岩储层发育。

Lithology Prediction of Upper Carboniferous in Mosuowan Uplift in Junggar Basin

A oversized anticline trap exists in deep Carboniferous of Mosowan uplift in Junggar Basin, but to explore deep oil/gas successfully,it is crucial to determine whether volcanic rocks exists in the upper Carboniferous or not. By comparing the features of oil/gas reservoirs inMosuowan uplift with those in its adjacent region, it is indicated that there are the large difference of magnetic and seismic anomaly betweenvolcanic and sedimentary rocks, but the magnetic anomaly and seismic facies feature of Moshen-1 well on the top of Mosuowan uplift aresimilar to those in oil/gas field in Shixi uplift, which is approached to the magnetic anomaly of middle-acid volcanic rocks, standing in thetransition belt from strong to weak magnetic anomaly. The analysis result of seismic facies shows that the majority of Mosuowan uplift has thefeature of strong amplitude reflection, and weak amplitude reflection is mainly distributed in the southeast sag of Mosuowan uplift. By integratingthe magnetic anomaly and seismic facies feature, it is inferred that the upper Carboniferous in Mosuowan uplift would have the followinglithologic-facies characteristics: middle-acid volcanic rock plus sedimentary rocks are mainly distributed in the central part of the uplift, andmiddle-basic volcanic rocks are distributed in the southwest and northeast limbs, and sedimentary rock is occurred in the southeast limb (Fang-2 well area) of the uplift, the central-southern part of Dongdaohaizi sag and Lunan-1 well area. The late reconstruction of Carboniferousvolcanic rocks in Mosuowan uplift has four favorable conditions, it is, therefore, inferred that the Carboniferous volcanic reservoirs would bewell developed in the uplift.