Известия Томского политехнического университета: Инжиниринг георесурсов (Sep 2019)
TECHNICAL SOLUTIONS FOR ESTIMATING WATER-CUT OF OIL WELL PRODUCTS
Abstract
The relevance of the research is defined by the need for standardization of oil products water-cut determining methods and techniques. The aim of the research is to assess the causes and conditions for occurrence of a systematic error in well products composition determining, to minimize errors in water-cut measurements by creating new technologies. The objects of the research are oil producing wells and the processes that occur during the movement of formation products from the bottom of the well to the standard sampler on the outflow line of the wellhead armature. The methods are based on selection of wellhead samples of well products before and after fluid homogenization in the flow line of the well. By the volumetric fluid samples selection technology the oil layer thickness above water was estimated using the developed device in which a fixed oil volume is transferred to a separating funnel by pressure reducing and adding an organic solvent to the oil. As the result of the research it was observed that in high-watered wells borehole fluid separates under the influence of gravity into layers with different contents of oil and water. Therefore the liquid, which flows into the sampling container, does not correspond to the composition of well products. The possible solutions of the existing sampling problem are considered in the article: the well flow must be homogenized before the standard sampler or the volumetric samples should be taken for a long period of time. The relative error in measuring the proportion of oil and water in volumetric samples using the developed device does not exceed 0,1 % for high-watered wells. The paper considers the alternative method for estimating the well products water-cut, based on using of two pressure sensors in a column of lift pipes above the electric centrifugal pump. The method meets the representativeness requirements of the estimated discrete borehole fluid samples.
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