Influence of the created drawdowns during wells operation on the productivity coefficient change in carbonate reservoirs
A considerable part of oil world reserves belongs to fields with fractured collectors. The main objective of the oil-producing industry is increase of production wells flow-rates. When developing the Ardalinsky group of oil fields of the Timano-Pechorsky province in carbonate collectors, productivity coefficient decrease with liquid withdrawals increase has been revealed for a long period of the fields’ operation. The wells fund of the fields is operated by electric-centrifugal submersible pumps (ESP). ESP operational capacity varies over a wide range. Selection of an optimum drawdown that provides wells operation in similar reservoirs allows to reach the most profitable flow-rates of wells. The paper presents the results and the analysis of the created drawdowns effect during wells operation on the productivity coefficient of a group of fields in carbonate reservoirs. The fields that were subjected to the analysis, are briefly described. The change of reservoir pressure dynamics is given. Graphical dependences of productivity coefficient on drawdown are given. Based on the results processing, some equations of inflow calculation when choosing the submersible pumping equipment are proposed.