Optimizing “Sleeping Reservoir” The Low-Quality Reservoir (LQR) of “BE_1” Sand at “Semangat” Field: Outstanding Performances, Further Opportunities, and Challenges

Abstract

“Semangat” field is one of primary field located at Wilayah Kerja (WK) Rokan, PT. Pertamina Hulu Rokan. First oil flowed in 1972 and reached peak production in 1974 with 28,865 BO. The production wells produce multiple reservoirs with simple ESP completions. Cumulative oil production was 92.4 MMSTB with current recovery factor is ~ 54%.

“Semangat” field has 4 major formations with distributed across the field. Over time, “D” and “M” Formation were the high-quality reservoirs and contributed the most oil production while “BE” and “BA” Formation where low quality reservoir with mostly produce with medium to low rates.

Lookback has been conducted with resulted low quality reservoir performance showed less production contribution when comingle with high-rate reservoirs. SM#007 was chosen as pilot well to produced single “BE_1” Low Quality Reservoirs (LQR) due to latest swab still shown 21 BPH/50% (2016). Surprisingly, SM#007 delivered excellent result by 564 BFPD/23 BOPD/96% WC although located at flank area.

This result was triggered to accelerate produce “BE_1” LQR Sand at attic position. SM#046 was the next pilot well to produce single “BE_1” and the result shown outstanding performance with initial production 456 BFPD/257 BOPD/44% WC. By this excellent result concluded “BE_1” was still has big opportunity to be developed.

The workflow process to developed “BE_1” LQR Sands was done by conducted integrated subsurface and engineering analysis such as: high resolution stratigraphic analysis, re-calculation petrophysics, fluid contact OWC analysis, and validated with production data. The final output is to identify sweet spot to optimized “BE_1” LQR Sands.

Outstanding performances was delivered by “BE_1” LQR Sands from 7 wells executed with deliver ~ 400 BOPD incremental oil, achieve > 70% success rate workover and well intervention job, and reducing fluid. Those result increasingly convincing “BE_1” LQR Sand was “sleeping reservoir” with huge oil potential. The probable estimation size of prize from “BE_1” LQR Sands reach > 1 MMBO and identify more than 10 wells could produce this big opportunity by revisit interval and add new perforation of the “BE_1” LQR Sand.

By having integrated and creative deep review and analysis can provide excellent result by deliver an opportunity to unlock Low Quality Reservoirs in “BE_1” Sand. Additional data such as surveillance log (CO Log) and additional new wells can increase the technical confident level to optimize the LQR Sands.