Estimation of the New Gas-cap to the Performance of the Reservoir of the Oil Field Libwa, Offshore of the Democratic Republic of Congo

Abstract

The quantity of hydrocarbons initially in place and the technique of exploitation employed in the reservoir determine the period of an oilfield. But the quantity of hydrocarbons in a reservoir defines as a preliminary the type of mechanism drainage which governs the pressure of the oilfield. And this pressure is the key parameter of the oil production. Thus, the mechanism of drainage is a motive element which shows the performance of an oil reservoir during the production. During the oil production in the Upper Pinda reservoir of the Libwa field, the mechanism of drainage used was that of gases in solution. It was noticed that during the production, an abrupt drop of the pressure of 2670 psia with 1567 psia and a cumulated production of oil of 239805 Stb at the end of the year 2018. However, certain studies undertaken in this field revealed the presence of a gas cap which could compensate for the mechanism with dissolved gas but which seemed to be ineffective during the drop pressure. Thus through our study, we put in evidence the existing quantity of gas in the primary gas cap which are worth 1.09414 MMscf under the basic conditions and with the factor of the primary gas cap (m) with 0.0018 who is scarcely and the new gas cap which is created starting from the addition of a quantity of dissolved gas released during the production of which the quantity of this gas is estimated at 1.86329 MMscf under the basic conditions and, the new factor of the gas cap (m) is worth 0.0059 and the value of this new factor of the gas cap (m) is almost null too. Taking into consideration these result, it is shown that this new gas cap will be always ineffective with the performance of the reservoir. On this it is necessary that the factor of the gas cap reaches a value at least equal to 10 to completely replace the mechanism with gas dissolved in the Upper Pinda reservoir in the Libwa field.