Half quantitative analysis of filling degree in caved type reservoir of fractured-vuggy reservoirs in Tahe oilfield

The caved type reservoir was a main reservoir space type of Ordovician fractured-vuggy carbonate rocks in Tahe-10 area,well production in the case of this type was very high,therefore,the identification of its filling degree was the key to determine the effectiveness of the caved type reservoir.The filling degree could be divided into three types:complete filling,half filling and no filling.By using drilling and logging,conventional logging and electric imaging logging,the intersection graph method was used to determine the reservoir filling degree.According to sensitivity characteristics of Th(radioactive thorium)to the cave filling reaction,the intersection graph between K(potassium)and Th was established,the value range of the intersection graph under different filling degrees was analyzed,and then the well logging response characteristics under different filling degrees were obtained.Through concrete well examples,the application results indicated the intersection graph between K and Th can effectively reflect the filling degree of caved type reservoir.