In the Ecuadorian Northeast Area, sand production has been associated with high porosity. Certain zones where the M-1 Sandstone has porosity above 25 % have experienced a lot of sand production. High rate gravel packs have been successful and more than 30 jobs have been successfully performed. As a rule on new wells with porosity above 25% a gravel pack system is installed on the initial completion.
One important fact is the wellbore cleaning process. On the first jobs, several products were pumped to avoid severe losses to the formation; but due to the high permeability (above 3,000 mD) and low reservoir pressure it was not possible to control that. Therefore to minimize production impairment attributed by invasion of contaminants into the gravel pack and formation, a well bore clean out procedure with a non-acid formulation was implemented to remove potentially damaging solids, including filtering all the water to 2 microns.
After the gravel pack, a phosphonic / HF acid treatment is pumped to both clean the gravel from any debris coming on the pumping and placement process and stimulate the producing zone. This treatment has shown excellent results on production and has diminished the effect of the additional restriction created by the gravel pack.