Tense economic situations push the demand for low-cost oil production,which is especially challenging for production in mature oilfields.Therefore,an increase in the life time between failures and limitation of equipment damage are essential.A significant number of wells in mature fields are suffering from sand by-production.The objective of this article is to show the development process and the testing procedure of an in-house built,effective downhole desander for sucker rod pumps,based on a sophisticated analytical design model.In weak reservoir zones,often the strategy to prevent equipment damage due to sand by-production is the sand exclusion method using a gravel pack.Nevertheless,a certain amount of small sand grains still enter the wellbore and may damage the sucker rod pumping system over time.In early 2018,various types and sizes of downho-le desander configurations were tested at the Pump Testing Facility (PTF) at the Montanuni-versitat Leoben.In a period of about four months,testing took place under near field conditions to find the optimum and most efficient design.The design optimization was focused on the geometry of the swirl vanes and the sand separation distance at the sucker rod pump intake.An analytical model provided the basis for geometric optimization.Concurrent field tests of the in-house downhole desander were performed in the Vienna Basin,which confirmed the findings of the tests at the PTF.The test results have shown that the system design and the pumping speed are the main parameters contributing to sand separation efficiency.Poor design in combination with badly selected pumping speed can reduce the sand separation efficiency to lower than 50%,while if all parameters are chosen correctly,the sand separation efficiency can be 95% or higher.The grain size distribution is an additional parameter that enables a decision and ranks the performance.The sensitivity analysis,performed for several downhole desander types,has shown the high dependency of the sand separation efficiency on the major desander design parameters.Proper selection of the components and operating parameters will contribute to an increase in the average time between failures.This article will present the testing configurations,the development of the high-efficiency in-house downhole desander,and the sensitivity analysis performed on the design.By C.LANGBAUER,M.HARTL,S.GALL,L.VOLKER,C.DECKER,L.KOLLER and S.HONIG*
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