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La Cira-Infantas (LCI) is Colombia's oldest oil field whose production started on April 18th, 1918. Since it is a mature field and is undergoing secondary recovery most of its wells have low flow rates (< 1000 BFPD). The wells require an artificial lifting system with low-cost installation and maintenance. For low flow and gassy wells in sandstone reservoirs, the Progressive Cavity Pump (PCP) system has been used since 2006. It has been observed that the smallest percentage of PCP failures is due to the pump. When a pump fails, it is necessary to determine if a component should be reused. Currently, when any work is performed on a well, the pump is inspected with a borescope. When the results show that the pump efficiency is 50% or higher, it is considered reusable. In addition, corrosion, scale formation, wear and abrasion from reservoir fluids should be identified to determine if the pump can be reused. A database was constructed of the history of the PCP in LCI. Each well had its run life, type of installed pump and the cause for any intervention. Thus, every pump model was classified, identifying all the interventions as pump failure or no-failure using failure codes. This data was used to obtain the Mean Time Between Failure (MTBF) calculation and its corresponding probability of survival, obtaining the initial criteria to reuse the pumps according to what was calculated and the experience and knowledge of the conditions in the field. This history, combined with the test bench efficiency analysis, assisted in determining if the pump was in good condition and a candidate for reinstallation. Today, when a pump is pulled out and successfully passes testing, its information is compared against every pump in the database. This enables a prediction of how much longer the PCP will last. After the estimate of reliability is calculated, the decision is made whether to reuse it or to reject it. |
