Study On Logging-based Fiuld Identification Of Carbonate Reservoirs

Fluid identification using well logging in carbonate formation is an important and difficult problem in logging data processing and interpretation. This paper summarizes carbonate fracture-cave reservoir, cave reservoir logging response characteristics, research logging fluid identification methods and the fluid identification method of the two-phase medium theory, summing up the effective fluid identification methods to this region.Firstly, information was collected, and fracture-cave, cave reservoir logging response characteristics of different fluid types were carried out. Next, sorts of fluid identification methods were studied, including RD and porosity, CNL and AC/DEN, GR and RD, RD and RD/RS intersection method, Pickett diagram method, P1/2 method and multi-parameter distinguishing method, by analyzing the conventional well logs in study area. Then, two-phase medium theory was studied in detail, and the procedure of fluid substitution based on logging data was formed, and the results were qualitatively analyzed. Finally, the application effect of all methods above was given in study area.Some results and progress were achieved. This paper summarizes the logging fluid identification characteristics of the different types of reservoirs, based on the cross plot was constructed fluid identification standards, especially, CNL and AC、DEN cross plot distinguishes between the oil and water layer has a good effect. Pickett templates and P1/2 processing module standard are constructed for the study area. Data mining method results show out the sensitive logging series of the fracture-cave reservoir and cavernous reservoir. Six identify indicators in the multi-parameter discrimination are summed up, and a multi-parameter determination module based on Forward software is formed. The result shows that oil saturation index, reservoir production rate indicators, relative water content percentage of indicators, apparent resistively of formation water index have high accuracy. Logging fluid substitution method is studied, this method was carried out in full of water, full of gas and oil fluid substitution, According to the changes of petrophysical parameters, through fluid substitution, such as density, velocity, and bulk modulus, carbonate fluid identification is achieved.