Research and application of evaluation method of interlayer pressure variation coefficient in multi-layer reservoirs
Author of the article:CAI Hui, SHI Hongfu
Author's Workplace：Bohai Petroleum Research Institute, CNOOC China Ltd., Tianjin Branch, Tianjin, 300459, China
Key Words：Multi-layer reservoirs; Pressure difference; Lorentz curve; Normalization; Quantitative characterization
Abstract：Pressure
is one of the core contents in oil reservoir development. At present, material
balance, pressure measurement, and well test analysis methods are used for the
evaluation of oil reservoir pressure. The original formation pressure and
bubble point pressure are used as the limit values to examine the overall
formation pressure maintenance in the field. Currently, this evaluation method
is too general and lacks the investigation and evaluation of the degree of
pressure difference between small layers in the vertical direction. In fact, in
the development process of heterogeneous reservoirs, the pressure difference
between layers objectively exists and will gradually aggravate to restrict the
improvement of oilfield development effects. The interlayer pressure difference
degree has a great influence on the water flooding status and safety production
of the vertical layers. In this paper, a method of evaluating reservoir
interlayer pressure varia based on Lorentz curve is proposed by referring to
economic Gini calculation method. Firstly, the test layers were standardized,
then the pressure values were accumulated and summed, then the Lorentz curve of
pressure difference degree was drawn. Finally, the pressure difference
coefficient was calculated. This method can not only process big data, but also
realize the normalized(0～1)
quantitative characterization of the reservoir interlayer pressure variation
coefficient, so as to provide intuitive support for the decisionmaking
of injection and production optimization in oil field.