东爪哇盆地抱球虫灰岩遗迹化石及其沉积环境分析

抱球虫灰岩是印尼东爪哇盆地已发现油气藏的主要储层岩性之一,是该盆地重要的勘探目的层.该套发育于上新世的抱球虫灰岩,其储层性质优,为高孔中高渗型性储层.但对该类灰岩储层的形成条件、沉积环境因缺乏可靠的相标志而认识不一,从而影响了对该类储层的油气勘探.通过对该套灰岩发育的遗迹化石研究,共识别出Ophiomorpha,Ast...

Ichnofossils in Globigerinid Limestone and Their Sedimentary Environments,East Java Basin

Globigerinid limestone is one of the main reservoirs in oil?gas reservoirs discovered in the East Java Basin， and also one of the main exploration targets. Developed in the Pliocene， Globigerinid limestone reservoirs are characterized by high porosity and medium?high permeability. However， the formation conditions and sedimentary environment of this kind of limestone reservoir are not well understood due to the lack of reliable facies markers， which affects the exploration for this kind of reservoir. Based on trace fossils preserved in the formation， a total of eight ichnogenera were identified: Ophiomorpha， Asterosoma， Palaeophycus， Thalassinoides， Phycosiphon， Zoophycos， Teichichnus and Terebellina. According to their ethological and morphological features together with the lithological characteristics of the host rock， three ichnoassemblages were established: （1） Ophiomorpha?Asterosoma ichnoassemblage， which developed in Globigerinid grainstone and packstone， represents grain beach deposition in the lower shoreface environment with medium?low hydrodynamic energy； （2） Ophiomorpha?Palaeophycus ichnoassemblage， which developed in Globigerinid packstone and wackestone， occurs in inner shelf lowland or offshore environments with normal marine and storm?induced depositions； （3） Zoophycos?Phycosiphon ichnoassemblage， which developed in wackestone and mudstone， represents an outer?shelf environment. Combining the paleosedimentary environment with the ichnogenera and ichnoassemblages， it is proposed that Globigerinid limestone was deposited in lower shoreface to outer?shelf environments， and its sedimentary model was also established. For the Globigerinid limestone in the study area， these conclusions have great significance， not only regarding its depositional genesis， controlling factors and distribution， but also for oil and gas exploration in this type of reservoir.