Kuwait Oil Company (KOC) is developing its shallow heavy oil field using thermal method. Top risk of this project is the cap rock failure. If failure occur, it may lead to the steam leakage, overlying aquifer contamination, ground heave or subsidence and surface collapse. For the monitoring ground deformation caused by cyclic steam stimulation (CSS) and steam flooding (SF) thermal operation in Kuwait, InSAR technology is being considered. Interferometric Synthetic Aperture Radar (InSAR) is a remote sensing technique to measure surface heave and subsidence.
First stage of heavy oil thermal development in North Kuwait comprises production from shallow Miocene reservoirs covering an area of roughly 30 square kilometers, by two or three cyclic steam stimulation (CSS) process followed by steam flooding (SF) process. Main reservoirs are the shallow Tertiary un-consolidated sandstone within the measured depth of 650 to 750 feet, sealed off by Up Shale layer that is about 30 FT thick. High pressure and temperature steam will be injected to reservoirs zones, which could result in cap rock breach causing surface heave or subsidence. High-precision and frequent measurements of surface deformation is very important for the study of cap rock integrity.
With the advancement of InSAR technology, millimetric precision of ground deformation measurement is possible. The important factors affecting measurement accuracy of ground deformation is Radar microwave length. The most common of microwave is the L band with 24 cm wavelength, the C band with 4-8 cm wavelength and the X band with 2.5-4 cm wavelength. The choice of wavelength influences the precision. However, there are some other factors which have impact on measurement quality such as spatial density of the measurement points, climatic condition, distance between the measurement points and reference points, number and temporal distribution of acquisitions.
InSAR technology is expected to provide regular surface deformation maps during heavy oil production to monitor the cap rock integrity and to optimize wells and reservoir management. This technology has many benefits, such as reliability, simplicity, low cost, weather independent, minimal field intervention and ability to acquire at night. The absence of vegetation growth in our field area makes this technology very effective. To increase the frequency of data collection and to improve the accuracy of the deformation maps, satellite ascending and descending images are also used. Use of ascending and decending images helps in calculating the vertical and horizontal deformations from the Line of Sight (LOS) measurmemnts.