PDF《John W. Buza1》

An Overview of Heavy Oil Carbonate Reservoirs in the Middle East* John W.

Buza1 Search and Discovery Article #10277 (2010) Posted November 22,

2010 *Adapted from oral presentation at AAPG Convention, New Orleans, Louisiana, April 11-14,

2010 1 Chevron Corporation, Houston, TX ([email protected]) Abstract Global heavy oil resources in carbonate rocks have been estimated to be on the order of 1.6 trillion barrels, of which about one\third may occur in the Middle East. Owing to its vast light oil reserves, documentation in the public domain on Middle Eastern heavy oil accumulations is not complete, but enough information is available to assemble a reasonable picture of the geological setting, reservoir and oil quality issues and the status of cold and EOR production in the region. Productive heavy oil carbonate fields can be grouped into two categories: 1) low matrix permeability, fracture dependent, and 2) matrix permeability dependent production. Fracture enhanced, low matrix permeability production is dominant and occurs in Oman, Iran, Iraq, Syria, Turkey and Egypt and includes producing fields such as Qarn Alam in Oman and Issaran and Bakr\Amer in Egypt. In Iran, several fractured carbonate fields have successfully cold tested oil qualities on the order of

10 degree API. Wafra, located in the Partitioned Neutral Zone (PNZ) of Kuwait and Saudi Arabia, is the most notable example of an accumulation that has ample matrix permeability to allow economic cold production without significant fracture enhancement. Ultimate recovery from these fields is heavily dependent on oil viscosity and the ability to lower it. EOR implemented in the region include a CO2 flood at Bati\Raman in Turkey, a full\field crestal steam injection project that is underway at Qarn Alam, and an ongoing pilot steam flood at Wafra that commenced in February 2006. These three fields, along with Issaran, where a CSS project began in 2006, constitute the bulk of carbonate heavy oil activity in the Middle East. Current carbonate heavy oil production is on the order of 100\150 TBD (0.5% of Middle East production) and will likely stay at that level until Wafra production is increased or fields with large potential, such as Ferdows in Iran, are brought onstream. References Meyer, R.F., E.D. Attanasi, and P.A. Freeman, 2007, Heavy oil and natural bitumen resources in geological basins of the world: U.S. Geological Survey Open-File Report 2007-1084, Web accessed October 15, 2010, http://pubs.usgs.gov/of/2007/1084/ Penney, R., R. Moosa, G. Shahin, F. Hadhrami, A. Kok, G. Egnen, O. van Ravestejin, K. Rawnsley, and B. Kharusi, 2005, Steam Injection in Fractured Carbonate Reservoirs: Starting a New Trend in Enhanced Oil Recovery (EOR): International Petroleum Technology Conference 21-23 November 2005, Doha, Qatar, SPE Paper No. 10727, Web accessed

9 November 2010, http://www.onepetro.org/mslib/servlet/onepetropreview?id=IPTC-10727-MS&soc=IPTC ? Chevron

2005 5An Overview of Heavy and Extra Heavy Oil Carbonate Reservoirs in the Middle East 3553-63-48-B April

2010 John W. Buza ? Chevron

2005 Middle East HO Carbonate Reservoirs Summary ? Difficult to obtain uniformly reliable data but can get "picture" Published STOOIP of 500-971 BBO vs.

130 BBO in published fields STOOIP estimates include all rock types but ME dominated by carbonates ? No demonstrated supergiants in inventory, Ferdows (Iran) and Wafra (PZ) possible ? Production of 125-200 TBD for foreseeable future (0.5% ME) Dominated by Wafra with small future increases in Oman & Egypt ? Rock Fabric is a key element for cold production Fractures required in low matrix perm, extra heavy oil reservoirs Good poro-perm overcomes need for fracture network (Wafra) ? Recovery factor most dependent on oil viscosity ? EOR underway includes CSS, Steamflood, TAGOGD & CO2 ? Chevron