Publications

Pertamina Hulu Energi Offshore Northwest Java (PHE ONWJ), as the operator of ONWJ Production Sharing Contract (PSC) is a part of Pertamina EP that has an important role in supporting national oil and gas production. It is very important for the PHE ONWJ to keep finding significant and economic resources despite the concession is classified as the brown field (mature). Therefore, the team has proactively been focusing on the new and / or under-explored plays other than the exhausted-classical play that usually relies on the structural closure. The recent GQX-1 discovery well just 17 km north of the Mike-Mike Field had proven that stratigraphic play remains attractive to provide large-sized hydrocarbon resources. Interestingly, this successful stratigraphic play was characterized by low-resistivity pay (LRP) of the Middle Miocene's Main and Massive intervals or known as Upper Cibulakan (UCB) Formation. Generally, the UCB Formation consists of interbedded shallow-marine sandstones, shales, and limestones with tidal influence. The GQX-1 well penetrated series of shale interbeds with unconsolidated, fine grained laminated sandstones with very poor visible porosity and low permeability. Based on X-ray Diffraction (XRD) analysis, the sandstone is dominated by clay minerals of 36 - 49 weight%, similar with the ones at Bravo, Echo, and Lima Fields, which successfully develop the LRP reservoirs. Dealing with the LRP reservoirs have many times been quite challenging, likewise the ones in the GQX-1 well are exacerbated by the presence of high-GR reading that makes the top of the reservoirs difficult to identify. Utilizing regional lithology markers close to the top of the LRP reservoirs and recognized its log characters when assessing well-to-well correlations. Pay-zone identification in the LRP reservoirs is to combine sets of petrophysical analyses such as RT-RO (resistivity log), DTS-DTC (sonic log), and Buckles plot. These analyses are combined with gas chromatograph analysis and neutron count rates in order to identify its reservoir content. Based on the petrophysical analysis there is about 40-ft oil and gas bearing reservoirs including potential tight zones, especially in the oil-filled interval. In order to flow oil to the surface most of the DST intervals are located at the bottom of oil column, while only few DSTs were positioned at the top of gas column. This technique allowed the gas column being the natural gas lift to avoid gas-locking phenomenon, which could impede the oil flow. As a result the DST had successfully been flowing 3.3 MMSCFD, 42 BOPD (oil just sprayed), 0 BWPD, and with SG of gas: 0.667, and oil API of 27.4. This rate will still be maximized using another suitable reservoir stimulation such as fracturing.