乐东—陵水凹陷黄流组峡谷水道储层特征及影响因素

峡谷水道沉积储层是深水区重要的油气储集层,琼东南盆地乐东一陵水凹陷中新统黄流组发育多期重力流峡谷水道,目前已在陵水区发现储量超1000×10~8m~3的大气田。为深入认识峡谷水道沉积优质储层形成机制,为下一步勘探部署提供依据,根据岩心与井壁取心资料,以及岩石薄片观察鉴定、扫描电镜、激光粒度、重矿物、X射线衍射等分析资料,研究了该区黄流组峡谷水道储层特征,并明确不同期次水道的差异(包括岩石组分、岩石结构、成岩作用与储集性等),进而分析储层岩相特征对沉积环境的指示,以及储层岩石学、成岩作用特征对优质储层发育的影响。结果表明:①研究区黄流组峡谷水道储层岩石类型以岩屑石英砂岩和长石岩屑砂岩为主,母岩类型以沉积岩、岩浆岩为主,部分为变质岩;②沉积水动力条件以重力流沉积为主,局部发育牵引流特征,其造成的储集岩粒度、分选性控制着研究区内优质储层的发育,伴随着牵引流改造的地区其优质储层更加发育;③弱一近强压实、局部碳酸盐胶结与异常超压是优质储层发育的重要控制因素。

Reservoir characteristics and influential factors of the Huangliu Formation canyon channel in the Ledong-Lingshui sag,Qiongdongnan Basin

Canyon channel is a kind of important hydrocarbon reservoir in deep water area. Multi-phase gravity flow canyon channels are developed in Miocene Huangliu Formation in the Ledong-Lingshui sag, Qiongdongnan Basin, and a large gas field with reserves of 100 billion m³ has been discovered in the Lingshui area. For a thorough understanding of the formation mechanism of high quality channel deposition reservoir to provide a basis for future exploration there, based on core and sidewall core data, as well as lab test data like rock slice observation and identification, scanning electron microscope (SEM), laser size, heavy mineral and X-ray diffraction, the reservoir characteristics of Huangliu Formation canyon channel were identified, and the differences (inclusive of rock constituents, rock texture, diagenesis and reservoir property) of channels in different episodes were ascertained. Furthermore, the indication of reservoir lithofacies features to sedimentary environment and the effects of reservoir petrology and diagenesis features on the development of high quality reservoirs were analyzed. The following results are obtained. First, the Huangliu Formation canyon channel reservoir is dominated by lithic quartz sandstones and feldspathic litharenites, whereas their parent rocks are dominated by sedimentary and magmatic rocks, followed by some metamorphic rocks. Second, the sedimentary hydrodynamic condition is dominated by gravity flow deposition, followed by traction current deposition locally; the resulted reservoir rock size and sorting property control the development of high quality reservoirs in the study area, whereas in the area accompanied by traction current transformation, the high quality reservoirs are more developed. Third, the weak & approximately strong compaction, local carbonate cementation and abnormal overpressure are the important factors controlling the development of high quality reservoirs.