Study On The Evaluation Method Of Typical Carbonate Gas Reservoirs In The Sichuan Basin

On the early development stage of carbonate gas reservoir, producting test data of whole gas reservoir and single wells are limited, and the dynamic data are also relatively short.This article, based on the main classification of specification of carbonate gas reservoirs in Sichuan basin, achives the goal of effective evaluations to early reserves, by using the combination of the material balance method and the investigation radius method with production dynamic data on early development stage, whether the production time is long or not. As the shortage of pressure testing data, the investigation radius method is accessible by geologic parameter, such as interpretive pemerbility, skin factor and so on. Therefore, another method, called the combination of wellhead material balance and wellhead deliverability eqution, is more applicable to reserve evaluation of early development stage.Those methods applicable to single wells, can be introduced to be applicable to the whole gas reserve calculations by using some ways to simplify them.Different from the ordinary sandstone gas reservoir, carbonate gas reservoir has inherently strong heterogeneity, and also should be considerd about the effect of double media.This paper surveys the related literature at home and abroad, combines with the specific gas reservoirs, and makes the research from several aspects as follows:(1) Through the relevant literature research, the characteristics of carbonate gas reservoirs in Sichuan basin will be summarized;(2) Study on calculation methods of bottom hole pressure in gas well;(3) Introduction and limitations of the calculation method for the reserves of ordinary single well;(4) The descriptions of calculation methods of single well reserves and total gas reserves in carbonate reservoirs;(5) Example calculation of carbonate gas reservoirs;(6) The design and implementation of the method of reserves evaluation.Finally, the study draws the following conclusions:the carbonate gas reservoirs in Sichuan basin were dominated on fracture-porosity reservoirs;based on ordinary single well reserves calculation methods, we get two carbonate early evaluation methods which are sutiable for the evaluation of Longgang and Longwangmiao carbonate gas reservoirs in Sichuan Basin;only on the condition that gas reservoir is with good connectivity, can we use gas reservoir equivalent method to realize the early reserves evalution of carbonate gas reservoir; if the gas reservoir connectivity is not good, the evaluation of the whole gas reservoir needs to be realized by the way of superposition of each single well in the reservoir.