Overview: Artificial Lift (May 2006)

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For the past several decades, artificial lift has referred to the traditional technologies of downhole pumping (e.g., sucker rod, electrical submersible, progressing cavity, and others) and gas lift. Today, a broader definition is emerging, a definition that can encompass the fundamental changes occurring in our industry. Today, artificial lift is no longer limited to methods applied in the wellbore, but instead must include methods used throughout the production system to "lift" the produced fluids to their final destination. For example, gas and heavy oil constitute a much larger portion of today's energy mix, driving significant changes in development philosophies. Today's heavy-oil developments make extensive use of multiphase production with long multiphase flowlines to tie wellsite production back to centralized processing facilities. Pressure losses in the surface multiphase gathering system can be significant, and a combination of downhole pumps and surface multiphase pumps often is required to effectively "lift" the fluids to the processing facility. Key issues for heavy-oil artificial lift include handling produced sand, increasing volumes of gas, and the high temperatures associated with thermal recovery projects. The booming natural-gas business has focused attention on artificial lift in gas and wet-gas developments. At the surface, wet-gas gathering systems have been found to provide advantages in terms of reduced capital expenditures and complexity. In this case, an important component of artificial lift is the boosting of the wet-gas stream through surface flowlines, which in the future may take the form of multiphase pumps and wet-gas compressors. In the wellbore, problems associated with lifting liquids from gas wells are well known. Today, several newer methods are being applied, such as the combination of flow-enhancement chemicals (e.g., surfactants) with downhole flow-enhancement tools. Deep water, ultradeep water, and other remote resources also have forced a broader definition of artificial lift. For deepwater and ultradeepwater developments, flow in risers and long subsea flowlines represents an important component of the production system. Intervention issues associated with subsea wells severely limit application of wellbore artificial-lift methods. Therefore, artificial lift is increasingly taking the form of seafloor multiphase-pumping and riser-lift methods. When searching for an artificial-lift solution, a wide variety of methods now must be placed "on the table" alongside the traditional methods we have used for decades. Artificial Lift additional reading available at the SPE eLibrary: www.spe.org SPE 95620 "ESP Model Implementation and Result Analysis Under Gas/Liquid Flow Conditions," by D. Sun, SPE, Baker Atlas, et al. SPE 97275 "Effect of Operating-Valve Performance on Stability of Gas Lift Wells," by Y.V. Fairuzov, SPE, Natl. Autonomous U. of Mexico, et al. SPE 93594 "Electrical Submersible Progressing-Cavity-Pump Application in Kulin Horizontal Wells," by M. Taufan, SPE, P.T. Caltex Pacific Indonesia, et al.