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AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain

Comprehensive History Matching a Complex Carbonate Reservoir (Maydan Mahzam Field, Offshore Qatar)

Ahmad Al-Ahmed2; Vance Fryer2; Mohammed Javed2; Abdulmalik Al-Abdulmalik2; Patrick Léandri3; Jean-Marc Chautu3; Romain Bohbote3; Marielle Inizan1; Christian Fraisse1

(1) Total, Paris, France.

(2) Qatar Petroleum, Doha, Qatar.

(3) Beicip-Franlab, Rueil-Malmaison, France.

The Maydan Mahzam field in offshore Qatar is a complex carbonate oil reservoir of the Late Jurassic Arab formation. It was brought on production in 1965, with a short period of natural depletion before starting water injection through dump-flooders located on the flanks of the reservoir. An integrated study has been launched by Qatar Petroleum in order to optimize the future development of the field and maximize the future recovery of the remaining oil in place. In this context the understanding of the main producing mechanisms of the past forty years is of major value. This requires reservoir modeling with extensive and detailed history matching.

This paper discusses the comprehensive methodology used to obtain a detailed and reliable history match of the Maydan Mahzam field. A high quality 3D reservoir model has been generated to properly represent the underlying geological concepts describing this multi-layer carbonate reservoir. Moreover, the reservoir presents a complex structural history, with a large number of faults of high throw, generating possible communications between the 4 main layers of the reservoir that are accounted for.

The following process has been applied to achieve history matching: the pressure response of the model was first analyzed and compared to the existing measured data, in order to qualify the pressure balance between the different regions of the model (crestal part vs. flooded flanks, faulted blocks). At the same time, the sweep efficiency of the dump-flooders as well as the aquifer was investigated for a better understanding of the production mechanisms involved in each part of the field. The main parameters affecting the model and its response compared to real production data were identified; their possible range was determined based on existing field data or analogs, in order to ensure the reliability of the final history match. To explore the possible combinations of these parameters in a systematic and efficient way, experimental design techniques were used, enabling quantification of the impact of each parameter on the model results, thus enhancing significatively the history match process. At this stage, a well by well analysis was carried out in order to correctly reproduce the water displacement within the reservoir at a detailed scale.

Finally, a comprehensive history match of the Maydan Mahzam reservoir was obtained: pressure history, water breakthrough and water cut history are reproduced in most of the 120 oil producers of the field. Also, the sweep efficiency within the reservoir is better understood. Based on this history matched model, reliable predictions can be made to optimize the production of the remaining reserves, and evaluate the feasibility of using enhanced recovery techniques on the field.