Prediction of new perforation intervals in a depleted reservoir to achieve the maximum productivity: A case study of PNN logging in a cased-well of an Iranian oil reservoir

Abstract

Pulsed neutron-neutron (PNN) logging is based on emitting neutrons into the near-wellbore zone and computing the neutron count decay due to scattering and capturing. The main application of this logging tool is to determine the current oil saturation and to detect channeling in perforated and non-perforated intervals behind the casing. Correct interpretation of the results obtained from PNN logging enables engineers to predict new perforation intervals in depleted reservoirs. This study examines the application of PNN logging in a well located in one of Iranian oil reservoirs. The interpretation procedure is described step by step. The principle of the PNN logging and the specifications of the tool are discussed and the applications of PNN logging in evaluation of oil saturation, identification of water flooded zones and prediction of potential perforating zones are described. Channeling is also investigated between all layers, good and poor oil zones are characterized based on the calculated oil saturations and new perforation intervals are suggested with the aim to boost oil production from the reservoir. The results of this study show that zones 1 to 5 having low oil saturations, are interpreted as depleted oil zones. Zones 6 to 8 are interpreted as good oil zones having high potential to produce oil. Zone 9 is interpreted as a water zone.

Keywords

Pulse neutron-neutron (PNN) logging / Sigma value / Remaining oil saturation / Conventional logging / Perforation intervals / Depleted reservoir

References

[1] Answers PMFQa, Hotwell Company, 2016, pp. 1-38.

[2] W.-j. Fang, Y.-r. FAN, F. Zhang, Study of thermal neutron time-spectrum of PNN logging based on multiscale filtering, Nucl. Electron. Detect. Technol. 3 (2010) 021.

[3] D.-X. Li, et al., Study on pulse neutron neutron (PNN) log and interpretation and its application in QingHai oilfield, Inn. Mong. Petrochem. Ind. 1 (2012) 056.

[4] L.-z. YOU, et al., Application of pulsed neutron neutron logging (PNN) in Dagang oilfield, Well Logging Technol. 6 (2007) 031.

[5] Z. Yusheng, Tuha operating department of logging limited, CNPC, Determination of Remained Oil Saturation by Pnn Log Data. World Well Logging Technology vol. 2, (2004).

[6] Dimon C.A., Use of Pulsed Neutron Logging to Evaluate Perforation Washing. 1984, Google Patents.

[7] F. TIAN, et al., PNN well log interpretation method and application, J. Jianghan Pet. Univ. Staff Workers 2 (2011) 011.

[8] A.A. Arbuzov, Memory pulsed neutron-neutron logging, SPE Russian Oil and Gas Exploration and Production Technical Conference and Exhibition, Society of Petroleum Engineers, 2012.

[9] H. Z.L.J.M. Huanying, L. Kun, An improvement of PNN logging interpretation and its application, China Offshore Oil Gas 2 (2009) 005.

[10] M. Li, Z.-l. Dai, Y. Xue, Application of PNN logging in water-out reservoir interpretation of Qinghai oilfield, J. Oil Gas Technol. (J. Jianghan Petroleum Inst.) 6 (2010) 064.

[11] R. Reischman, et al., Horizontal Cased Hole Evaluation Using a New Pulsed Neutron Spectroscopy Tool and Dipole Sonic, Unconventional Resources Technology Conference (URTEC), 2017.

[12] B. Raeesi, et al., Expanding application of multi-detector pulsed neutron instrumentation for quantitative gas saturation monitoring in gas-filled boreholes, SPWLA 58th Annual Logging Symposium, Society of Petrophysicists and Well-Log Analysts, 2017.

[13] Y. Kim, et al., Innovative triangulation technique enables simultaneous determination of three-phase formation fluid saturations using pulsed neutron logging, SPWLA 58th Annual Logging Symposium, Society of Petrophysicists and Well-Log Analysts, 2017.

[14] J. Liu, et al., Methods for evaluating elemental concentration and gas saturation by a three-detector pulsed-neutron well-logging tool, SPWLA 58th Annual Logging Symposium, Society of Petrophysicists and Well-Log Analysts, 2017.

[15] P. Bartelucci, et al., Pressure depletion evaluation behind casing using pulsed neutron technology: an application in a multi-layer gas reservoir in Eastern “pianura padana” basin, Offshore Mediterranean Conference and Exhibition, 2017 Offshore Mediterranean Conference.