Two-rate drawdown test analysis to determine reservoir characteristics for the well (6J9-E59) in North Gialo field

The North Gialo field was discovered at the beginning of 2002. The first well that yielded commercial quantities of oil is well 6J-1. This paper applies the Russell and Pinson methods to assess reservoir characteristics through a two-rate drawdown test analysis for well 6J9-E59 in the North Gialo field, which was selected for this test due to its unstable production rate. The main objectives include estimating permeability, skin factor, and flow efficiency, as well as determining average reservoir pressure. Results reveal that the estimated value of reservoir permeability is 0.0354 md and the average skin factor is -1.021, indicating that the well has been treated successfully. The well flow efficiency is 133.83%, reflecting the improvement in well performance due to the treatment, and an average reservoir pressure of 9217.56 psi is determined using the Mathews, Bronze, and Hasbrouck (MBH) method. The investigation radius of 21.031 ft obtained from the test duration is relatively shallow, indicating limited influence around the well. This can have several implications: a shallow investigation radius suggests that the well may be encountering a confined area of the reservoir, potentially limiting overall drainage and recovery efficiency. To obtain a more comprehensive understanding of the reservoir, additional testing or longer-duration tests may be needed. This can help in assessing the flow characteristics over a broader area. Test duration of 225,048.9 hours is required to reach the reservoir boundary. Moreover, fluctuations in production rate do influence the accuracy of the study results. Results show favourable conditions for production optimization, with significant flow efficiency and a negative skin factor, have been obtained. These findings will inform future strategies for well completion and reservoir management. Keywords: North Gialo field, Russell and Pinson methods, Reservoir Characteristics, Two-Rate Drawdown Test, MBH Method.