Before 1990 the most important criterion for the development of a reservoir was to produce it, the economic considerations playing a secondary role.
Initial oil in place estimation was based on geological and/or engineering available data, but great errors were introduced in measuring and registering those data due to the low technology level. Usually the reserves were overestimated, the production level being established depending on the available technology without any reason for efficiency.
Therefore it was necessary for the Romanian petroleum industry not only to improve terminology but to review the methodology of reserve's evaluation, mainly in conception, by changing the reserve's classification to the international standards.
The paper presents an analysis of the impact of the new economical conception in Romanian reserves reevaluation regarding the efforts, the effects and the risks that are implied by this goal.
There are presented the results of this analysis concerning the exploration, development and production activity, including the production level efficiency with respect to a reference date.
The results of a feasibility study presented in this paper put in evidence the impact of the new criterion involved in reserve reevaluation and the risks implied by this activity.
The reserve classification still in use in Romania is similar to that used in the Former Soviet Union (FSU). An analysis of the reserve classification systems used in the FSU and in the United States (U.S.) with respect to the World Petroleum Congress (WPC) and SPE definitions is made by Grace, Caldwell and Heather'.
The transition period to a free market economy imposed the translation of Romanian reserve from the old classification to a new one corresponding to the international standards. In this context it was decided to analyse what are the implications for reevaluation of reserve and resources. At first sight it seems that the translation process is quite easy to fulfill, but the experience from the last three years showed many more difficulties than we expected.
First of all it was realized that neither one of the classification is perfect. Second, 'reserve definitions have evolved in response to specific goals" and will be evolving in this manner. Third, a tremendous work had to be done because all the known reservoirs from Romania had to be analyzed for their whole production life and checking for each case the specific parameters to upgrade the reserves to the new system. However we managed to obtain some very interesting results that make us more confident in continuing our efforts to integrate Romanian reserves in the new standard.
The paper presents the results obtained in the process of reevaluating the reserves from all major geological units of Romania.