4D seismic assisted history matching Using ensemble-based methods

Introduction

4D seismic data sets can provide valuable insights when characterizing a reservoir. However, assimilating these datasets into reservoir models is challenging due to their size and lack of flexibility. Choosing parameters that will enable history matching while remaining geologically plausible given other data can also be problematic.

Conditioning to 4D seismic data

The ResX 4D module enables a 4D seismic data history matching workflow. Developed in 2018-2019 through a joint venture involving four operators and two service companies, the ResX 4D module is uniquely flexible, adapting to the specifics of each project and open to third-party components. This module enhances the use of 4D data for reservoir characterization, providing users with a better understanding of reservoir connectivity, flow barriers, and bypassed hydrocarbons.

Flexibility

The ability to select the response allows users to adopt the matching data best suited to the project’s objectives. Similarly, the choice of domain offers flexibility (Figure 1). For example, it is generally quicker to move an interpretation of measured data into the simulation space for comparisons, but if time and resources permit, simulator results can be processed and made available for comparison in the seismic domain.

Figure 1: ResX provides the ability to adopt the matching data and model domain best adapted to the project’s objectives.

Quantitative use of 4D seismic data

In the ResX objective function, 4D seismic data is represented as a 2D surface. Multiple surfaces can be included, such as one per extraction window and one per time-lapse interval. In an ensemble-based study, the 4D workflow outputs an ensemble of reservoir models consistent with static, production, and 4D seismic data, while capturing uncertainty. This enhances decision-making for assets using 4D seismic data and helps operators position themselves to increase ultimate recovery.

Qualitative use of 4D seismic data

A vital part of the ResX 4D module is the qualitative ensemble analysis visualization and the available QC tools. Perform statistical analysis of the objective function and visually analyze 2D surfaces and 3D properties to quickly identify areas of interest (Figure 2). Use interactive filters to pinpoint areas where prior model assumptions need revisiting.

Figure 2: ResX 4D Seismic can help to quickly identify areas of interest by performing statistical and visual analysis.

Summary

The ResX 4D Seismic supports a 4D seismic data history matching workflow and offers maximum flexibility in selecting the response and domain for comparing simulation results with the 4D signal.

By increasing the use of 4D seismic data for reservoir characterization, users can generate more comprehensive ensemble models. This leads to a better understanding of reservoir connectivity, the location and nature of flow barriers, and the volumes of bypassed hydrocarbons.

References

Wojnar, K. et al., 2020. Quantitative 4D Seismic Assisted History Matching Using Ensemble-Based Methods on the Vilje Field. Paper presented at the SPE Annual Technical Conference and Exhibition, Virtual, October 2020. Paper Number: SPE-201750-MS