Substance balance method for predicting carbon dioxide flooding oil reservoir indexes

Abstract

The invention provides a substance balance method for predicting carbon dioxide flooding oil reservoir indexes. The substance balance method for predicting the carbon dioxide flooding oil reservoir indexes comprises the following steps of: 1, giving application conditions of a carbon dioxide flooding substance balance equation; 2, building a substance balance equation applicable to the carbon dioxide flooding; 3, storing oil reservoir parameters and determining a calculation parameter; 4, calculating the parameters of the corresponding time period, wherein the parameters of the corresponding time period include the oil yield and the gas injection volume; and 5, using the parameters obtained through the calculation in the fourth step to determine the carbon dioxide flooding oil reservoir indexes such as the injection-production ratio and the recovery percent. The substance balance method for predicting carbon dioxide flooding oil reservoir indexes has the advantages that the substance balance equation which considers the compressibility of the oil reservoir rock fluid and is applicable to the carbon dioxide flooding is built; an application method of the substance balance equation is given; and an effective method is provided for predicting the carbon dioxide flooding oil reservoir indexes.

Description

technical field [0001] The invention relates to the technical field of petroleum development, in particular to a material balance method for predicting carbon dioxide flooding reservoir indexes. Background technique [0002] Carbon dioxide flooding plays an important role in enhanced oil recovery (EOR). In 2012, the EOR production of carbon dioxide flooding in foreign countries accounted for 24% of the total EOR production; domestic carbon dioxide flooding has also gradually received attention, and it has begun to be applied in Shengli, Jilin, Zhongyuan and other oilfields. Therefore, it is necessary to predict the engineering indicators of carbon dioxide flooding reservoirs (production degree, injection-production ratio, etc.) to guide the rational and efficient development of carbon dioxide flooding reservoirs. [0003] At present, the reservoir development index prediction methods mainly include production dynamic methods, numerical simulation methods, and material balan...

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Problems solved by technology

[0003] At present, the reservoir development index prediction methods mainly include production dynamic methods, numerical simulation methods, and material balance methods; the production dynamic methods mainly combine oilfield production data to draw water flooding curves or decline curves to predict reservoir development indicators. This method has certain accuracy , but a large amount of oilfield production data is required. For blocks with fast development or short development history, the production dynamic method cannot be used; the numerical simulation method can accurately determine the reservoir development indicators by establishing a geological model and fitting the production history. However, this method has high requirements on the geological model, and it is difficult to establish a fine geological model in the early stage of oilfield development. In addition, the application of numerical simulation methods in low-permeability reservoirs with threshold pressure gradients is also limited; The reservoir material balance method is the application of the law of mass conservation in reservoir engineering. The material balance principle is simple and the method is practical. It is widely used in the prediction of various indicators in oil and gas field development.

[0004] The traditional material balance method is only applicable to water flooding reservoirs. At present, there are few reports on the application of the material balance method in the prediction of carbon dioxide flooding reservoir indicators. Some scholars (Xia Hairong, Guo Ping, Liu Bin, et al. and immiscible displacement mass balance equation [J]. Southwest Petroleum Institute, 2005, 27 (2): 61-63) established a mass balance equation considering the mass transfer between oil and gas phases, but it ignored the reservoir rock fluid Compressibility, and there are strict requirements on the acquisition of mine data

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