When gravel packing horizontal wells, operators usually deploy conventional, and commercially available gravel pack proppants in the industry. Several jobs have been successfully completed up to date with no considerable concerns. However, under certain unfavorable conditions, a better option to gravel pack these wells is ultra-lightweight proppants.
Deepwater well, extended reach horizontals, low fracture gradients, washed out zones, and insufficient fluid returns to circulate conventional proppant in place are good examples where lighter weight proppant is needed to assure the complete packing of the open hole.
This paper summarizes the development and application of the ultra-lightweight media and associated technologies for horizontal well gravel packing. Pioneering case histories will also be reviewed from the initial wells treated. The wells were completed on a field in the Campos Basin, offshore Brazil, where the reservoirs are sandstones, highly unconsolidated and therefore require a method of sand control.
The most common proppants used in horizontal gravel packs in Brazil are resieved sands and ceramics. These particles' density (from 2.65 to 2.73 g/cc) leads directly to high degree of difficulty with regards to proppant transport (see Figure 1), hence, increased dune height will happen and premature screen-out might occur at low pump rates. A lesser density would be easier to transport with un-viscosified fluids like completion brines, allowing for reduced pump rates to be used to circulate proppant at the bottom of the screen and successfully gravel pack the entire horizontal open hole.
In this context, the ultra-lightweight proppants can span the pumping window to perform the OHGP's (open hole gravel pack) in an easier and safer way. An ultra-lightweight proppant with a specific gravity of 1.25 g/cc (ULW-1.25) can overcome most of the problems faced with conventional proppants, and mitigate the difficulties with Extended Reach Wells (ERW), low fracture gradient, washout zone packing and fluid loss while pumping.
A flow loop apparatus was used to measure and observe the transport characteristics of ultra-lightweight proppants, and compare to sand and ceramic proppants also. Slurry flow properties and ion of alpha-wave dune height as a function of wellbore and pumping parameters were determined in order to help engineers to design and execute OHGP.
Three case histories will be presented where ULW 1.25 has been successfully used in deepwater offshore injector wells in the Albacore East field, Campos Basin, Brazil.