Target reservoir and production characterization study was carried out in Pematang Lantih field, Jambi, Indonesia. The Talang Akar Formation has 10 underlying reservoirs from 600 m to 900m TVDSS. This multi-layers sandstone structure is driven by regional tectonic stress and complicated by several faults. Sharp oil well production decline was observed during 3 years period since initial production in 2015, with GOR increase. Arresting production decline was the key objective for efficiency increase, hence improved reservoir characterization was needed, as cross-well reservoir properties/interference were unclear. Multiwell Retrospective Test (MRT) is a recent development used to study reservoirs by carrying out automatic matching of historical production rates and bottom hole. It provides practical, fast yet robust analysis for reservoir evaluation. It can quantify inter-well pressure interference and evaluate cross-well reservoir properties. The main goal of this study was to get better reservoir understanding and evaluate ability of this technique to deliver additional value at current reservoir conditions, considering initial data availability/quality.

The key technology element used is multi-well pressure deconvolution, which is a highly parallelizable decoding algorithm running on multi-core workstation. The analysis is carried out on historical well pressure and production data. Hence no field operation is needed and there is no production deferment since it does not require additional field data acquisition. The technique delivers formation pressure history and productivity index history in tested well reconstruction. It is also proficient to reconstruct cross-well interference and estimate cross-well transmissibility from offset wells towards the tested well. Another result is evaluation of formation pressure decline impact on oil production of the existing wells.

The study area has reservoir pressure that dropped below bubble point and continues declining. Historical data over 3 years, from a cell consisting of 4 producers was analyzed using this technique. The analysis found uniform formation transmissibility between the analyzed wells at Pematang Lantih field. Transmissibility was estimated by analyzing cross-well transient responses (CTR) calculated with multi-well deconvolution. CTR is a function representing BHP response to neighbor well single rate production. CTR is interpreted with interference test technique thus estimating transmissibility values.

The analysis result confirmed that all 3 offset wells have a pressure impact towards the pressure-tested well (PLT-X) with quantified values. Connectivity analysis showed the expectation of rapid production decline if there was no pressure maintenance system. The recommendation was to estimate the economics of pressure maintenance system implementation in order to improve production performance.

By using multi-well deconvolution analysis, the entire 3-years cell production history was converted into a single unit-rate pressure transient that enabled deep reservoir investigation and calculation of field reserves undisturbed by dynamic well boundaries.

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