From Feasibility to Processing: A Time-Lapse Seismic Experiment On Al Khalij Field – Offshore Qatar

Time lapse seismic survey (aka 4D seismic) is a geophysical tool used by the industry to guide and maximize field development. It has been proven successful mainly in clastic deposits environment (Gulf of Mexico, Gulf of Guinea, North sea,…) but sparsely tested on carbonate fields because of seismic quality concerns. Total E&P Qatar engaged in 2012 a “proof of concept” 4D pilot study on its operated Al Kahlij field – offshore Qatar- to demonstrate the value of information provided by a 4D seismic in a middle-east carbonate field under development. This study is made of: A feasibility study which aims to quantify the expected 4D effect by using a petro-elastic model and several chosen depletion scenarii. These input data are used to compute a synthetic time-lapse seismic dataset through a massive seismic modeling. A 4D pilot seismic survey shot in summer 2012 (monitor) which was designed to repeat the first seismic survey shot in 1998 (base). A dedicated seismic processing of both base and monitor in Total’s 4D processing dedicated center followed by a specific inversion process (time warping) to extract the awaited 4D signal. The main objective on Al Khalij field is to validate that 4D seismic is able to calibrate the reservoir model and make it more predictive. If successful, the time-lapse seismic survey concept can be envisaged for other carbonates field in Qatar and in the Arabic Gulf area for field development optimization.