Comprehensive justification of the errors at hydraulic calculation of the reservoir pressure maintenance system

Abstract

Relevance. The need to determine the permissible errors of hydraulic calculations of surface pipelines of the reservoir pressure maintenance system. This must be done, among other things, due to changes in the properties of produced water. As a result of the transition of most fields to the late stages of development, the water content of the extracted products increases, the composition and properties of reservoir waters change due to the breakthrough of the injected water. These circumstances can lead to significant changes in the mineralization, composition and Ph of water, which must be taken into account in numerical modeling. Aim. Creation of a nomogram for estimating the error in the course of changing the properties of produced water for numerical modeling of the operation of pressure pipelines of the reservoir pressure maintenance system. Methods. Hydraulic calculations in the engineering process simulator software, analysis of the properties of produced water samples in the laboratory, assessment of the density of produced water samples in the PVTSim 20 software product. Results. The studies were carried out on samples of produced water taken from seven wells. The value of salinity in the reservoir pressure maintenance system during the year varies from 247.85 to 327.79 g/dm3. The calculated density varies from 1188 to 1255 kg/m3. To calculate the pressure at the mouth of the injection well during water injection, samples with the highest, average and lowest density were taken. Analyzing the obtained data, a strong effect of water properties on the values of wellhead pressures is noticeable. On the basis of the conducted studies, a nomogram was created to determine the degree of influence of changes in water properties in the course of hydraulic calculation, taking into account the specific-injectivity index of injection wells and the length of pipelines. Conclusion. In the course of numerical modeling, it is quite difficult to take into account all the parameters that affect the accuracy of the calculations obtained. To do this, it is proposed to use the created nomogram, which allows estimating the permissible errors of hydraulic calculation taking into account the variability of the properties of water sent to the reservoir pressure maintenance system.

Keywords

• water properties
• produced water
• pressure losses
• numerical modeling
• reservoir pressure maintenance system