Shell Egypt and the joint Venture partners Vegas and GDF Suez are currently developing the Karam gas field by drilling 4 new wells, working over two existing wells and installing surface facilities to process and export this new production. The field is operated by Bapetco (a Shell/EGPC Joint Venture) on behalf of the Joint Venture Partners.
The Abu Roash G reservoir is approximately 4400 meters deep and with reservoir pressures and temperatures in excess of 9500 psi and 310 deg Fahrenheit respectively it is technically challenging. The reservoir is over pressured and Calcium Bromide brine was required to kill the wells for the work over activities.
Post-workover well productivity was significantly below expectations with very high well skins observed. The root cause for the productivity loss was believed to be from formation damage due to losses during the workover operations but relative permeability effects (water blocking) was also suspected as a potential productivity damage mechanism. Laboratory tests were carried out which showed the creation of a sever emulsion between the completion fluid used during the workover (CaBr, CaCl, CaCO3) and reservoir fluids.
A novel technical solution, a methanol Channel Fracturing treatment was developed to restore well productivity. This was a world first application of this treatment utilizing the Channel Fracturing treatment technology to reduce the required pump rate/pressure to place the treatment and methanol as the carrying fluid to minimize the water block effect.
The well was tested after the methanol Channel Fracturing stimulation at a constrained rate of 35 MMscf/d and 3000 bpd condensate compared to the pre-stimulation gas rate of 2 MMscf/d.
This paper will discuss planning, execution and production results making recommendations to improve the effectiveness of future Channel Fracturing applications.
Karam-3& 4wells were drilled as part of 4 wells campaign to explore and appraise the gas potential in Karam filed. The wells succeeded to find large gas volumes in Kharita reservoir which has high Co2 percentage. The wells also found sweet gas in Abu Roash G reservoir but with smaller volumes which could be produced through the existing facility.
Abu Roash G reservoir was tested in Karam 3 with an initial rate of 23 MMscf for few days and then the well was shut-in due to an integrity issue in the completion. The other well Karam 4 was tested only on Kharita formation and Abu Roash G formation was not tested due to an integrity issue also in the completion, however from log response it was expected that Abu Roash G in Karam 4 should produces at good initial rate similar to Karam 3 as the sand quality looks similar in both wells from the logging data. Fig.1 shows a correlation panel between Karam 3 & 4 and the sand quality in both wells.
Turkey, Laila (KOC) | Hafez, Karam Mohamed (KOC) | Vigier, Louise (Beicip) | Chimmalgi, Vishvanath Shivappa (Kuwait Oil Company) | Dashti, Hameeda Hussain (Kuwait Oil Company) | Datta, Kalyanbrata (KOC) | Knight, Roger (KOC) | Lefebvre, Christian (Beicip-Franlab) | Bond, Deryck John (Kuwait Oil Company) | Al-qattan, Abrar (KOC) | Al-Jadi, Manayer (Kuwait Oil Company) | De Medeiros, Maitre (Beicip) | Al-Kandari, Ibrahim (Kuwait Oil Company)
A pilot water flood was carried out in the Marrat reservoir in the Magwa Field. The main aim of this pilot was to allow an assessment of the ability to sustain injection, better understand reservoir characteristics. A sector model was built to help with this task.
An evaluation of the injectivity in Magwa Marrat reservoir was performed with particular attention to studying how injectivity varied as injected water quality was changed. This was done using modified Hall Plots, injection logs, flow logs and time lapse temperature logs.
Data acquisition during the course of the pilot was used to better understand reservoir heterogeneity. This included the acquisition of pressure transient and interference data, multiple production and injection logs, temperature logging, monitoring production water chemistry, the use of tracers and a re-evaluation of the log and core data to better understand to role of fractures.
A geological model using detailed reservoir characterization and a 3D discrete fracture network model was constructed. Fracture corridors were derived from fractured lineaments interpreted from different seismic attribute maps:
A sector model of the pilot flood area was then derived and used to integrate the results of the surveillance data. The main output is to develop an understanding of the natural fracture system occurring in the different units of the Marrat reservoir and to characterize their organization and distribution. The lessons learned from this sector modeling work will then be integrated in the Marrat full field study.
The work described here shows how pilot water flood results can be used to reduce risk related to both injectivity and to reservoir heterogeneity in the secondary development of a major reservoir.