大王北洼陷湖相滩坝砂体风暴沉积特征

THE CHARACTERS RESEARCH AND ANALYSIS ON TEMPESTITE DEPOSITS OF SANDY BEACH –BAR SEDIMENTS IN DAWANGBEI SAG

通过对大王北洼陷钻井岩心精细观察,及对洼陷资料重新分析,发现大王北洼陷沙二段为盆地断坳期,盆地呈"碟"状,地势平缓,广泛发育浅水漫湖砂质滩坝沉积.浅水环境下原有的正常砂质滩坝沉积极易受风暴流作用,接受风暴搬运的沉积物,并受风暴流后期改造,形成风暴沉积.大王北洼陷沙二段整体呈细质沉积的滩坝砂体中粗粒泥质沉积,是由风暴沉积作用形成的,这一认识为解释滩坝砂体沉积成因提供了新线索,对该区岩相古地理恢复和油气勘探具重要意义.

In this paper,we study the works of other researchers,and analyse the core of oil well and other data of Dawangbei sag.Base on these works,the result indicate that taphrogeny or depression is the main tectonism in different period,but the taphrogeny is weak in the whole period.The whole structural relief is acetabuliform.And the sag is an classical shallow water over-lake in the Shahejie 2nd formation fault-depressed period.Sandy beach-bar is the main sedimentary sandy body.Because the water is very shallow,the beach and bar easily was affected by the windstorm wave.Primary sandy beach-bar was reformed and accept the tempestiti sediments.Mud gravel that continually appear in the beach-bar is the production of srorm.This conclusion is new evidence of the sandy beach-bar forming.And the discovery and analysis of tempestites is very important for reconstructing the palaeogeography and further oil and gas exploitation.