ANALYSIS OF THE PERFORMANCE OF THE TSHIENDE OIL FIELD DURING WATER INJECTION

We analysed the efficiency of the production technique used by Perenco in the Tshiende oil field in the Democratic Republic of Congo. Initially, this field produced oil by natural drainage, based on the mechanisms of fluid expansion and rock compressibility. However, in 1986, a drop in reservoir pressure led to a reduction in production, making it necessary to adopt water injection to compensate for this loss and optimize hydrocarbon recovery. This research responds to the imperative of satisfying growing energy demand while preventing the early abandonment of fields. We used a data storage unit, a computer system and specialized software to process and analyses the data collected. The results show that water injection has considerably improved field performance. Oil production increased and the average reservoir pressure remained above the bubble pressure (927). In addition, the volume of water produced (128907050 m3) gradually exceeded the volume of water injected (107348149 m3), demonstrating the effectiveness of the reservoir sweep. However, variations in the injection rate created imbalances between injection and withdrawal. In 2014, the Voidage Replacement Ratio (VRR) was equal to 1, indicating a temporary equilibrium. The relationship between oil production and VRR confirms that the production rate is directly dependent on the amount of water injected, signalling inactivity in the aquifer. Between 1986 and 1991, the production of oil and water was almost equivalent, but currently, the production of water exceeds that of oil, indicating that the water produced is greater than the water injected. Thanks to the injection of water, the recovery rate for the Tshiende field has increased significantly, from 2.6% to 39.8%, due to the improved efficiency with which the oil is displaced. A volume of water corresponding to that of the pores occupied by the hydrocarbons exceeds 0.90, showing that water saturation is greater than that of the oil. In conclusion, water injection has proved to be an effective solution for extending the productive life of the Tshiende field and improving its recovery rate. We recommend that the company continue to investigate the existence of an aquifer in the field and explore other development campaigns, particularly in the Pinda reservoir, where the results promise new production opportunities.