走滑断裂断控碳酸盐岩油气藏的特征与井位部署思路——以塔里木盆地为例

Characteristics and well location deployment ideas of strike-slip fault controlled carbonate oil and gas reservoirs:A case study of the Tarim Basin

塔里木盆地碳酸盐岩油气藏是我国深层油气勘探开发的重点领域之一,近年来该盆地的勘探目标已逐渐转向以断裂为主控因素的北部坳陷,但对于断裂控储控藏的认识不清,加之储层埋藏深、开发成本高,因而制约了该区的油气高效开发。为此,在分析塔里木盆地北部坳陷区域地质概况的基础上,系统分析了断控碳酸盐岩油气藏和储层的特征,明确了走滑断裂对油气藏的控制作用,进而提出了该类型油气藏的井位部署思路。研究结果表明:①该盆地北部坳陷发育晚加里东期、晚海西期、燕山期走滑断裂,形成了3层构造样式;②北部坳陷断控碳酸盐岩储集层主要分布在奥陶系一间房组—鹰山组,储集空间主要为溶蚀及构造破裂作用形成的孔、洞与裂缝,沿断层储层改造十分强烈,溶洞、洞穴发育,发育洞穴封闭型、洞穴洞缘型和裂缝孔洞型3种类型的断控溶蚀型储层;③深大走滑断裂具有明显的“控储、控藏、控富集”作用,北东向断裂优势控藏;④总结出“主干油源走滑断裂+正地貌+多相位串珠状反射”的高效井特征,形成定区、定段、定井、定型的“四定”断控油气藏整体井位部署方法。结论认为,新的井位部署思路提高了钻井成功率和高效井比例,实现了塔里木盆地断控油气藏的高效开发,对同类油气藏的开发部署具有借鉴意义。

Carbonate oil and gas reservoirs in the Tarim Basin are one of the important fields of deep oil and gas exploration and development in China.In recent years,the exploration targets in this basin have gradually shifted to the northern depression which is mainly controlled by faults.However,the efficient development of oil and gas in this area is hampered by the unclear mechanisms of fault controlled reservoirs and hydrocarbon accumulation,great reservoir depth and high development costs.After investigating the regional geological situations in the northern depression of the Tarim basin,this paper systematically analyzes the characteristics of fault controlled carbonate oil and gas reservoirs and their reservoirs and clarified the control effect of strike-slip faults on oil and gas reservoirs.On this basis,the ideas on the well placement in this type of reservoirs were put forward.And the following research results were obtained.First,the strikeslip faults of Late Caledonian,Late Hercynian and Yanshan period are developed in the northern depression of the Tarim Basin,which form a three-layer structural style.Second,the carbonate reservoirs in the northern depression are mainly distributed in Ordovician Yijianfang Formation–Yingshan Formation.The reservoir space mainly includes pores,vugs and fractures which are formed by dissolution and tectonic rupture.The reservoirs are reworked strongly along the faults,and dissolved caverns and cavities are well developed.And thus,three types of fault controlled dissolved reservoirs are developed,i.e.,cavern sealing type,cavern edge type and fracture-vug type.Third,discordogenic strike-slip faults have an obvious effect of"reservoir control,hydrocarbon accumulation control and enrichment control",and the NE trending fault is dominant in controlling hydrocarbon accumulation.Fourth,the high-efficiency well characteristics of"strike-slip fault+positive geomorphology+multi-phase bead reflection"in the main oil source are summarized,and the well location deployment method of"four determinations"is put forward,including zone determination,stage determination,well determination and trajectory determination.In conclusion,the new well location deployment idea improves the drilling success rate and the efficient well ratio,realizes the efficient development of fault controlled reservoirs in the Tarim Basin and is of referential significance to the development deployment of similar oil and gas reservoirs.