The Formation Of Neogene Reservoir In Oikou Depression

In this paper,the requirements of oil-bearing rock,reservoir and caprock,which formed the Neogene reservoir in Qikou depression are analyzed. The geological actions and process which are imperative and indispensable to form the reservoir in Neogene, are systematicly studied. The regularity of accumulation distribution is ascertained and directs the exploration orientation.the main results obtained in this paper are:1.The analyses of hydrocarbon-bearing rock,reservoir,caprock and oil & gas reservoir indicate the source of oil&gas,the space for reservoir,requirement for preservation,reservoir type and its basic characters.2.It is realized by the analyses of sealing up capability of caprock and faults,and fault'slatter stability from microcosmic and macroscopic that the wide-spread regional caprock of Nm T prevented oil&gas of Neogene from diffusing fault movement in Neogene less violated and fault displacement decreased,which are advantageous for the preservation of oil&gas reservoir.And latter structure movement usually formed the accunulation of oil & gas in Neogene.3.The research of history of hydrocarbon generation and expulsion of main hydrocarbon-bearing rock in Qikou depression reveals the threshold depth and the fime of hydrocarbon generation and expulsion. The main process of hydrocarbon generation and expulsion in Es3 hydrocarbon-bearing rock began in the late of Ed epoch and ended in Ng epoch(equals to 30-12Ma).The generation and expulsion of oil of Es1 epoch began in Nm ?epoch and ended by the deposition of Quaternary system(equals to 10-5Ma) and reached its peak after the deposition of Nm epoch.4.The types of of oil&gas are systematicly summarized.There are three basic type:First: Lateral migration along layers with medium distance formed self-producing oil reservoir of Neogene.Second:Migration along fault with short distance formed shallow oil reservoir.Third: Lateral migration along interlayer and unconformity with long distance.Meanwhile,the function of fault which palyed in the secong migration of oil&gas are discussed and indicated that time of fault movement,combination type of fault and fault movement caused the difference of layer's attitude between the two fault walls and face to face lithologic relationship greatly influenced the orientation and scales of oil & gas second-migration.5.By summarizing the distribution regularity of existing oil&gas fields,it is found that all kinds of oil&gas reservoirs are distributed around the Qikou depression like rings,which are divided into inner ring oil-bearing belt,infer ring oil-bearing belt and outer ring.The inner ring is central of oil-bearing region in Qikou depression,which is controlled by HaiHe faults andQidong faults.The inter ring is in regions which are prospect for oil and regions with paleogeographic background of low-gradient slogze.The outer ring is regions.which are outside the oil-bearing region and inside the oil & gas migration region,with paleogeographic background of buried-hill and faults controlling the basin,ect.6.The forming regularity of oil & gas reservoir of Neogene in shallow ocean regions which are less explored in Qikou depression are studied and are summaried into two models:one term+episodic type and ladder type.7.It is indicated the prospects for exploration are BeiDagang bueried-hill-drape-lik fold oil accumulation belt,Baidong Structure belt and Chengbei fault step oil accumulation belt,which directs the explorations of Neogene in Qikou depression.