Artificial lift methods are used to extend the lifetime of brownfields. Gas lift is widely used worldwide, since natural gas is available and relatively inexpensive in many situations. Gas lift injection can be continuous or intermittent towards the final production period. The application of foamer is an innovative way to improve the efficiency of gas lift, reducing the weight of the liquid column in the tubing and reduces flow instability, given by the slug flow pattern.
Chemical injection via gas lift system presents many challenges, associated to the chemical formulation and the field application.
The chemical formulation shall be specifically designed in a laboratory phase, to address to the requirements of product stability and injectivity. The paper will go through the specific tests needed to make sure that the foamer will not cause gunking in the annulus and will be able to reach the gas lift valve where it's actually injected into the tubing.
The field application requires an appropriate operative procedure to ensure that the injection via the gas lift stream will be safe and effective. Nonetheless some unexpected challenges came out during the field trials, that required further analysis and improvement of the procedure.
During the application of foamer via gas lift, it has been observed a stabilization in the flow pattern of the production throughput from slug to continuous, this gives the possibility to evaluate the well performance analysis in a new way, therefore optimization of the application is ongoing.
Preliminary field applications gave successful results showing consistent foaming and the relative change of the flow characteristics.
Combination of foamer with gas lift has been proven to give an enhanced artificial lift capacity to gas lifted oil wells in brownfields.
Gas lift is an artificial lift method used in mature oilfields where a source of gas is easily available, for example in reservoirs producing with high GOR (Gas Oil Ratio). In this case gas compressors are always installed to manage associated gas and can be designed to match the injection pressure required for gas lift. The flexibility of gas lift can hardly be matched by other methods of artificial lift if adequate gas pressure and volumes are available (petrowiki.org).
