Carbonate bitumen

Introduction

It has become increasingly attractive for the oil industry to turn its attention to developing effective exploitation and production techniques for known heavy oil deposits, due to the current decline of conventional oil reserves and strong commodity prices. Advances in heavy oil recovery technology and production methods in Western Canada have been targeted towards Basal Cretaceous sand reservoirs, due to the enormity of these deposits, which are estimated to contain 1.7 trillion barrels Original Oil in Place (OOIP). Heavy oil is being produced from Carbonates in the Bashkir Romashkino oil field in Tatarstan using a microbial improved oil recovery.

Discussion

Carbonate Triangle

Considerable attention is currently focused on the large heavy oil deposits in the "Carbonate Triangle" of northeastern Alberta as displayed on the map to the right. The Upper Devonian aged Grosmont formation has been the main focus of interest because of its enormous heavy oil reserves, estimated in the range of 300+ billion barrels OOIP. It is anticipated the Grosmont will be a particularly challenging reservoir because of its complex heterogeneity, caused by faulting and karstification. Extensive research is being directed towards new solutions to recover heavy oil and bitumen from carbonate rocks, which has shown considerable promise in similar reservoirs through other parts of the world. Effective new solutions are rapidly emerging at a markedly accelerated pace, as compared to efforts in oil sands recovery technology developed over the last two decades.

The figure shown below illustrates that Western Canadian bitumen reserves represent about 45% of the world total. Although the large majority of these heavy oil reserves are in Cretaceous sands, considerable reserves are also hosted within carbonate rocks (limestones). Alberta is destined to become the largest heavy oil production and development center in the world.

In global markets of high energy pricing and demands, industry is focused on innovative solutions to address effective exploitation of heavy oil from carbonate reservoirs, as was successfully accomplished with heavy oil sands. Recently developed in situ bitumen extraction techniques will allow industry to leap-frog through this challenge.

Carbonate Heavy Oil Production in the Global Arena

In the late 1990's, Scimitar Hydrocarbons began efforts to develop the Issaran Heavy Oil Carbonates in Egypt by in-situ application of heat and steam. This project was initially viewed with considerable cynicism, but was ultimately a highly successful venture for Scimitar's successor Rally Energy who sold their interest in the field back to the Egyptian Government last year for $900,000,000. Heavy oil is being produced from Carbonates in the Bashkir Romashkino oil field in Tatarstan using a microbial improved oil recovery (ref: 8) from fractured porous carbonate reservoirs by the application of molasses and bacteria. This application appears to be more effective in carbonates than with sand reservoirs since carbonates neutralize generated organic acids, which intensifies the formation of microbial bacteria, and therefore increasing permeability.

In May 2007, Petroleum Development Oman awarded two major engineering, procurement and construction contracts for the Qarn Alam (16 API) steam-injection project. This project includes drilling some 150 wells and installing facilities to treat ...