More Oil from the Well: Foam Increases Yield

Siemens researchers collaborating with the Russian oil companyRosneft have developed a process for boosting extraction of oilfrom wells. At present it is possible to extract only roughly between30 and 40 percent of the oil in a well, on average; the restremains in the deposit. Oil producers around the globe are workingto improve this yield. The new process from Siemens uses anacid-bearing foam to clean oil wells very efficiently. This frees thereservoir rock from substances that block the movement of oil,which can then flow more readily to the borehole. Rosneft wasable to significantly increase the flow at several wells using themethod.

The earth does not give up its black gold willingly: On average,only about ten percent of the oil bubbles up on its own out of thethree to six kilometer-deep boreholes. Several tricks can be usedto increase the yield. Injected water, gas, or steam increases thepressure in the well. Hot steam and gases such as carbon dioxidealso lower the viscosity of the oil. The new method is based on along-used means of cleaning oil wells that involves use of an acidsolution to dissolve unwanted impurities including calcium, gypsum,and barium sulfates in the oil-bearing sediments. Theseimpurities block the flow of the oil to the borehole. This treatmentis generally performed every two to five years. A large shareof the solution seeps into the porous rock, however.

Researchers from Siemens Corporate Technology in Russia begantheir efforts to gain higher yields by analyzing the oil wells incomputer simulations and developing a model for a new foamacidtreatment. Rosneft provided a wealth of data on the individualwells, including borehole depth, permeability, pressure ratios,and flow rates, thus enabling the researchers to assess the treatment'seffect.

Rosneft is now using the method to increase extraction. Thechemical foam seals porous areas in the rock, and the acid mixturesubsequently introduced into the well flows to points whereobstructions are waiting to be dissolved. Rosneft tested the procedureat 27 oil wells and succeeded in increasing the flow by anaverage of 17 tons per day. Without the foam, the wells producedonly 8.6 additional tons.

Use of the sealant also reduces the amounts of chemicals requiredfor the cleaning process. This saves money and lessens theimpact on the environment. Siemens now wants to work withRosneft on projects for the extraction of oil from oil shale. A correspondingfeasibility study is now in progress.

Photo: http://www.siemens.com/ct-pictures/in20090703