Analysis On The Features And Causes Of Abnormal Pressure In The Paleogene And Neogene Of Dina 2 Gas Field,Tarim Basin

By analyzing lithology,well-logging,sedimentary and tectonic evolution,burial history of Dina 2 gas field via geology,logging and well-drilling profiles,this paper probes into the feature and major causes of abnormal pressure distribution in Dina 2 gas field's Paleogene and Neogene.This paper focused on the Paleogene and the Neogene strata lithology,hydrocarbon geological characteristics,structural characteristics and the reservoir formation process of Dina 2 gas field;It also expounds the sedimentary characteristics of Kuqa depression on the basis of the tectonic evolution since the Mesozoic in Tarim basin;According to the profiles of field formation pressure testing,well logging,well drilling,and burial evolution history,this paper gives a comprehensive analysis of the abnormal formation pressure and the well logging responses to overpressure in Dina 2 gas field both in horizontally and vertically.Based on nowadays research results,this paper analyses 3 types of probable overpressure formation mechanisms respectively,including the mudstone undercompaction,tectonic compression and fluid filling.The time when the abnormal high pressure was formed primarily is also confirmed approximately.In the last part,this paper takes some real examples of gas field development to discuss the influences brought by abnormal high pressure on well completion,production etc.The result shows that the formation pressure in the field could be divided into 3 different systems,with a normal one on the top,a high overpressure one in the middle,an overpressure one at the bottom,it shows that the gypsolyte exerts huge influences on the overpressure;It also shows that the undercompaction resulted from rapid deposition,tectonic compression and the hydrocarbon filling are the major causes of overpressure.