碳酸盐台地内部滩相薄储集层预测——以四川盆地威远地区寒武系洗象池群为例

Prediction of thin shoal-facies reservoirs in the carbonate platform interior:A case from the Cambrian Xixiangchi Group of the Weiyuan area,Sichuan Basin

以四川盆地威远地区中上寒武统洗象池群颗粒滩储集层为例,结合储集层成因机制分析,探寻预测滩相薄储集层分布的地质方法。滩相储集层发育受颗粒滩厚度控制,而颗粒滩的沉积速率和规模与微地貌高地密切相关,微地貌高地在稳定构造背景下可以较长时间继承发展。据此,提出了利用相对较短时间内形成的、以颗粒岩沉积为主的近等时地质体的厚度变化近似刻画沉积期微古地貌和储集层发育概率的方法,并在资料条件极差的威远地区中上寒武统洗象池群建立了滩相薄储集层预测地质方法。利用该方法对研究区滩相薄储集层分布进行了预测,与后期钻探实践结果对比,该方法预测效果良好,可为滩相薄储集层的勘探提供参考依据。

This paper presents a geological prediction method of thin shoal facies reservoir through the analysis of shoal facies reservoir＇s genetic mechanism of the Middle-Upper Cambrian Xixiangchi Group in the Weiyuan area, Sichuan Basin. The development of shoal facies reservoirs is controlled by shoal thickness. Both sedimentary rates and scales of the shoal are closely related to microtopographic highs, which can develop inheritably for a long time under a stable tectonic background. So we present a prediction method that depositional microtopographic highs and shoal reservoirs＇ development probability can be portrayed by the thickness variation of isochronal geological bodies, which mainly composed of grain stone formed in a short time. Based on it, a prediction model was built for thin shoal facies reservoirs of the Middle-Upper Cambrian Xixiangchi Group, where useful geological data are extremely poor. The method was used to predict the distribution of shoal facies reservoirs within the research area. Later drilling showed that the prediction is consistent with the drilling result. This study can provide reference to the exploration of shoal facies reservoirs.