CHARACTERIZATION OF SALDANADI GAS RESERVOIR BY WELL LOG INTERPRETATION

Abstract

In this study, we have compared several petrophysical parameters such as facies, porosity, and shale volume for the various zones of the Saldanadi Gas Field (SGF), Bangladesh, using 2D seismic and logging data. The SGF is a part of the greater Rukhia structure. It is located in Kasba Thana of the Brahmanbaria district in Bangladesh, adjacent to the border with Tripura, India, and about 50 kilometers southeast of Brahmanbaria town. We have used seismic and logging data as input, along with a combination of Petrel Software (2009.1.1) algorithms, to simulate the potential zones of this field. Also, log data is used to correlate Gas Sand Zones among the four wells which are drilled yet, those are: Saldanadi (SD)-1, SD-2, SD-3, and SD 4. The goal of this study is to determine the possible gas sand zones of the Saldanadi gas reservoir for each individual well based on the input data. Gamma-ray logs have been used to determine the lithology for each well. Based on the SD-1 facies model four possible gas sand zones have been determined and they are namely New Gas Sand-2 (NGS-2), New Gas Sand-1 (NGS-1), Upper Gas Sand (UGS), and Lower Gas Sand (LGS) respectively from the top. For the wells SD-1, SD-2, SD-3, and SD-4, the Measured Depth (MD) of NGS-2 is 1866–1913 m, 1940–2010 m, 964 –1014 m, and 2154–2272 m, respectively. For the SD-1, SD-2, SD-3, and SD-4 wells, the depth of NGS-1 is 1999m–2012m, 2225m–2260m, 1052m–1230m, and 2402m–2423m, respectively. The UGS depths for the SD-1, SD-2, SD-3, and SD-4 wells are 2206–2259 m, 2323–2330m, 1388–1410 m, and 2618–2633m, respectively. For the SD-1, SD 2, SD-3, and SD-4 wells, the LGS depths are respectively 2304m to 2369m, 2417m–2439m, 2184m–2224m, and 2673m–2710m. In SD-01, the porosity has been found 16.61% for NGS 2, 18.81% for NGS-1, 16.11% for UGS, and 13.83% for LGS. In SD-2, the porosity is 12.73%, 13.24%, 9.61% and 10.65% for NGS-2, NGS-1, UGS and LGS. In SD-3, the porosity for NGS 1, UGS and LGS are 13.5%, 9.5% and 9% respectively. On the other hand, the shale volume is found 18.5%, 0.27%, 2.28%, and 0.72% for NGS-2, NGS-1, UGS, and LGS zones respectively in SD-1. The shale determined for SD-2 are 0.27%, 10.61% and 19.42% respectively for NGS-1,UGS and LGS. The SD-3 has a the shale volume of 0.44%, 16.03% 3 and 21.7% for NGS-1, UGS and LGS respectively.The NGS-1 has a shale volume of 7.26%, UGS 6.596% and LGS 1.2% in SD-4.