The Application of Rate Transient Analysis for the Production Performance Evaluation of the Temane Gas Field–Mozambique: The Use of the Per-Well Basis Approach

The Temane gas field, the first producing natural gas field in Mozambique, remains a key supplier to southern Mozambique and the South African market. In recent years, however, the field has experienced an accelerated production decline, raising concerns regarding its long-term supply sustainability. Between 2020 and 2024, gas production decreased by approximately 25%, motivating a comprehensive reserve assessment to quantify the remaining potential and support informed reservoir management. This study applied three modern rate transient analysis (RTA) methods (Blasingame, normalized rate–cumulative, and flowing material balance) to twenty years of daily production data from thirteen producing wells across three reservoirs (G-9A, G-9B, and TEast) on a per-well basis. The RTA methods yielded consistent estimates, indicating an original gas-in-place value of 1576.38 Bscf, a remaining gas-in-place value of 503.37 Bscf, an estimated ultimate recovery of 1405.25 Bscf, and a field-average recovery factor of 76.35%. Reservoir-level recovery factors are estimated at 79% for G-9A, 74.92% for G-9B, and 58.01% for TEast. Despite the high depletion level, the magnitude of the observed production decline is not fully explained by reservoir exhaustion alone, suggesting that the field retains significant remaining recovery potential.