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Overview of 4-D Seismic Feasibility Studies in Oman

Al-Busaidi, Said S.*1; Maskari, Yahya A.2
(1) Geophysics, Petroleum Development of Oman, Muscat, Oman. (2) Geophysics, Petroleum Development of Oman, Muscat, Oman.

The decline in oil production in the matured fields, coupled with the increase in demand for hydrocarbon and the rise of oil prices, drives oil companies to enhance oil production from existing fields. Petroleum Development of Oman (PDO) is currently deploying several different Enhance Oil Recovery (EOR) techniques such as steam/hot water injection, water flood, miscible gas injection and polymer.

One of the key factors for the success of any EOR project is the early monitoring of the injected fluid and identification of any bypassed or upswept oil. Time lapse seismic has proven to be of value in monitoring field activities such as steam injection, water flood and CO2 injection.

Before acquiring dedicated base and monitor surveys, a time lapse seismic feasibility study is carried out to assess the expected acoustic impedance change and appropriate timing to acquire a monitor survey. The feasibility study uses the measured and modelled data to represent the conditions and rock properties for different EOR techniques. In this paper the focus is on assessing the technical Probability Of Success (POS) of being able to observe changes in rock properties that can be detected by seismic for different EOR methods. We use the reservoir scorecard presented in Lumley et al (1997) to rank different PDO fields (clastic and carbonate rocks) for different EOR methods.

We will present the results of the feasibility studies which will show, that shallow clastic fields undergo thermal EOR have the highest POS, whereas very deep carbonate reservoirs showed the lowest POS to observe any 4D seismic signal. This reflects the change in intrinsic properties of rock, or lack of it, for a given EOR method. It has been concluded that not all EOR methods are feasible for 4D seismic surveillance.

 

AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain