Researchers at StatoilHydro have developed a mild chemical treatment which gently strengthens weak reservoir rock without impeding oil flow.
Although weakly consolidated reservoir rocks usually have the desirable properties of high porosity and permeability, they can often cause problems because small particles and sand grains are dislodged and carried along with the flow of water and oil.
This sand production phenomenon may erode flow lines and other equipment.
Remedial measures include reducing (choking back) the flow rate or injecting chemicals into the formations to strengthen them artificially.
Unfortunately, both methods reduce the production capacity of a well. Standard chemical treatments for sand consolidation often transform weak sandstones into solid, impervious rock.
By contrast, StatoilHydro’s new mild chemical technique imparts sufficient strength to a friable producing formation to withstand the forces generated by the flow.
Small incremental increases in strength improve the visco-elastic binding between sand grains without detrimentally blocking the pore system.
This newly patented treatment has been successfully applied to several wells on the Norne field operated by StatoilHydro in the Norwegian Sea.
One of these, on template B, is producing about 12,500 barrels of additional oil per day compared with the pre-treatment flow.
The cost of the treatment will also be recouped within hours.
Operational disruption is minimal because the chemical is pumped directly into the formation while the subject well is shut down. Oil production is then slowly resumed some six to nine hours later.
The method is being considered for use on the Heidrun field operated by StatoilHydro to the south of Norne, and has recently been licensed to a service company.
