Integration of 3D-seismic and petrophysical analysis with rock physics analysis in the characterization of SOKAB field, Niger delta, Nigeria

S S Bodunde,P A Enikanselu

doi:10.1007/s13202-018-0559-8

Abstract

Compartmentalization of reservoirs and technical failures experienced in data acquisition, processing and interpretation, without doubt, hinder the effective characterization of reservoirs. In this research, to ensure accuracy, three methods were integrated to characterize reservoirs in SOKAB field. Petrophysical analysis, seismic interpretation, and modeling, and rock physics analysis were utilized. Its objectives were: to develop a template to facilitate improvements in future reservoir characterization research works and producibility determination; to utilize rock physics models to quality check the seismic results and to properly define the pore connectivity of the reservoirs, and to locate the best productive zones for future wells in the field. Forty-three faults were mapped and this included five major faults. Two hydrocarbon bearing sand units (A & B) were correlated across five wells. Structural maps were generated for both reservoirs from which majorly fault assisted and dependent closures were observed. The petrophysical analysis indicated that the reservoirs have good pore interconnectivity (Average Фeffective = 23% & 22% and Kaverage = 1754md & 2295md). The seismic interpretation and modeling alongside the petrophysical analysis were then quality checked via qualitative rock physics analysis. From the Kdry/Porosity plot, the sands were generally observed to lie within the lower Reuss and upper Voigt bound which indicates a low level of compaction. From the velocity–porosity cross plot, it was revealed that the lower portions of the reservoirs were poorly cemented and this could hinder their producibility.

Highlights

In economically unstable times as this in the oil industry when work-over operations in low producing and abandoned wells are more common than new prospects, the best methods must be utilized together to ensure that by-passed and lowly producing reservoirs are restored to a state of productivity that yields maximum profit.According to Ailin and Dongbo (2012), it is common knowledge amongst industry experts that reservoir flow properties control the amount of producible hydrocarbon from reservoirs and as such these factors (such as porosity,1 3 Vol.:(0123456789)Journal of Petroleum Exploration and Production Technology (2019) 9:899–909 as acoustic impedance and velocity, rock physics should be used alongside Seismic models and measured reservoir properties (Mavko et al 2009)
The observed seismic properties were cross-plotted against the calculated petrophysical parameters to quality check the results of the petrophysical analysis and to further define the connectivity of the reservoirs
The results from the petrophysical analysis, seismic interpretation, and rock physics cross-plot analysis are displayed below: The qualitative petrophysical analysis resulted in the identification of two hydrocarbon bearing sands

Summary

Introduction

In economically unstable times as this in the oil industry when work-over operations in low producing and abandoned wells are more common than new prospects, the best methods must be utilized together to ensure that by-passed and lowly producing reservoirs (either due to failure of technicians or Compartmentalization) are restored to a state of productivity that yields maximum profit.According to Ailin and Dongbo (2012), it is common knowledge amongst industry experts that reservoir flow properties control the amount of producible hydrocarbon from reservoirs and as such these factors (such as porosity,1 3 Vol.:(0123456789)Journal of Petroleum Exploration and Production Technology (2019) 9:899–909 as acoustic impedance and velocity, rock physics should be used alongside Seismic models and measured reservoir properties (Mavko et al 2009). Keywords Reservoir characterization · Lower Reuss · Upper Voigt · Petrophysics · Rock physics · Cross-plots Utilizing only petrophysical analysis and seismic data separately in characterizing and determining producibility of reservoirs gives a fairly conclusive result.

Results

Conclusion