North Sea Case Study of an Integrated Sim2Seis Workflow

Tabatabaei, Mohammad (Marathon Oil Company) | Milovac, Jadranka (Marathon Oil Company) | Bastidas, Rodrigo (Marathon Oil Company) | Lau, Ryan (Marathon Oil Company) | Jameson, Eric W. (Marathon Oil Company)

OnePetro 

Abstract

Simulation to Seismic (Sim2Seis) is a forward modeling technique used to predict/generate synthetic seismic response from a static or dynamic reservoir model. There are two key components of a Sim2Seis workflow: reservoir model (geological and/or simulation model) and petro-elastic models (PEMs). PEMs are rock physics functions which relate reservoir properties such as rock types, porosity and fluid saturation to the elastic properties such as compressional and shear velocities, and density. Predicted elastic properties are used to compute reflection coefficients, when convolved with a wavelet generate a synthetic seismic volume (1D or 3D).

There are several applications for Sim2Seis in reservoir characterization. It can be applied to test the consistency of a 3D geological static model, or of a history-matched simulation (dynamic) model with the actual seismic data. It can also be applied to study the impact of saturation change on seismic response (4D effect). A case study from an oil producing Tertiary age field in the North Sea was used to illustrate the applications of Sim2Seis workflow. This case study reveals the value of integrating the static and dynamic data for more accurate reservoir characterization, and consequently building a more reliable reservoir flow model which honors petrophysical and seismic data as well as production data.

Introduction

The Alvheim Field is comprised of several hydrocarbon accumulations, known as Kameleon, East Kameleon, Boa, and Kneler which are located in Norwegian North Sea blocks 24/6 and 25/4 (Fig. 1), bordering the United Kingdom. Alvheim is located in the central part of Viking Graben where deepwater deposits of the Paleocene and Eocene (known as the Rogaland Group) have been the main exploration targets (Fig. 2). The main sediments present in the Rogaland Group (Fig. 3) are siliciclastics with minor coal, tuff, volcaniclastics, marls and reworked carbonate sediments which were sourced from the East Sheldland Platform. Coarser sediments were reworked and redeposited during three major episodes of sea level fall in this period (Brunstad et al., 2009). The main coarse clastic units of the Rogaland Group are Ty, Heimdal and Hermond Sandstones interbedded with Lista and Sele Shales. All producing fields within Alvheim are producing from the Palaeocene Heimdal Sand Member of the Lista Formation.