Quantitative Characterization of Tidal Couplets in Oil Sands Reservoir, the Upper McMurray Formation, Northeastern Alberta, Canada

Zhiquan Nie,Hao Chen,Jixin Huang,Xiaoxing Shi,Zhongwei Wu,Jiuning Zhou,Zhaohui Xia

doi:10.2113/2021/2993537

Abstract

AbstractThe McMurray Formation, NE Alberta, Canada, is one of the most significant bitumen bearing deposits worldwide. This formation deposited and reworked in fluvial, tidal, or estuarine environments results in a huge number of tidal couplets (TCs) which is consisted of mm-cm scale sandy and muddy interlayers. These couplets not only increase the geologic heterogeneity of the oil sand reservoir but also make it hard to predict the performance of in situ thermal processes. In this paper, based on literatures, lab analysis, core photos, logging, and drilling data, a quantitative characterization procedure for mm-cm scale tidal couplets was proposed. This procedure, which includes identification, classification, quantitative description, and spatial distribution prediction, was presented. Five parameters, thickness, mud volume, laminae frequency, spatial scale, and effective petrophysical properties, were selected to describe the TCs quantitatively. To show the procedure practically, TCs in the oil sand reservoir of McMurray Formation, Mackay River Project, and CNPC, were selected to demonstrate this procedure. The results indicate that the TCs are in mm-cm thickness, densely clustered, and in a variety of geometries. Based on geologic origins, these couplets were divided into four types: tidal bar couplets (TBCs), sand bar couplets (SBCs), mix flat couplets (MFCs), and tidal channel couplets (TCCs). The thickness, mud volume, and frequency were calculated by mathematical morphological processed core photos. The spatial scale of TCs was estimated by high-density well correlations. The effective petrophysical properties were estimated by bedding scale modeling and property modeling via REV. Finally, the spatial distribution of TCs was predicted by object-based modeling.

Highlights

The oil sands or tar sands, which play an important role in the world energy market, are one typical unconventional hydrocarbon resource [1, 2]
Lab analysis, logging, and drilling data, the identification, classification, characterization, and distribution prediction of tidal couplets (TCs) were done through mathematic morphology process, bedding-scale modeling, representative elementary volume (REV), and object-based modeling
TCs offer the following characteristics: (1) they are in mm-cm scale thickness with great variation

Summary

Introduction

The oil sands or tar sands, which play an important role in the world energy market, are one typical unconventional hydrocarbon resource [1, 2]. Large amount of oil sand reservoirs is found and in production in Athabasca, Cold Lake, and Peace River, northeastern Alberta, Canada [3, 4]. The bitumen in these reservoirs below 75 m only can be extracted commercially by in situ thermal methods, steam drive, and steam-assisted gravity drainage (SAGD) etc. The upper well is used to inject steam in the reservoir zone, thereby slowly heating and mobilizing the bitumen. The heated bitumen, liquid, flows via gravity down the margins of the developing steam chamber and into the production well below [7]. The recovery ratio of SAGD is high, it is badly influenced by strong reservoir heterogeneity, especially in the McMurray Formation which bears plenty of tidal couplets [8, 9]

Objectives

Methods

Results

Conclusion