At present, Daqing Oilfield is at the stage of oil production with high watercut. As the watercut of fluid produced from oil production wells is increasing higher, the two profile logging data are also progressively required. Alongside the oil recovery technological applications of polymer flooding and ASP flooding, it is more and more difficult to measure the two profiles. In view of this situation, the logging techniques for measuring fluid injection and production profiles used appropriately at the stage of oil production with high watercut and polymer injection flooding are developed. In this paper, these logging technologies and their applications in Daqing Oilfield are introduced. It is mainly with focus on introducing the through casing-tubing annulus logging techniques.
The fluid injection profile and production profile logging data play an important role in an oilfield development. The two profile logs can provide performance data for the geological analysis and offer the data for hydraulic fracturing, acidizing and chemical water shutting off (WSO) treatments in water injection wells and oil production wells, and therefore, the logging data can be also needed for evaluating the operating effects. The logging can be used to monitor developed areas systematically to study the conditions of producing reserves and watered out conditions for adopting an appropriate injection-production plan for increasing production and oil recovery efficiency.
Due to the specific geological and developed condition in Daqing Oilfield, the two-profile logging calls for higher demands. Daqing Oilfield is a large non-marine sedimentary reservoir with multisand oil zones, and the output of the oil production well is low and watercut is high. Since most oil wells in the oilfield are pumping well, the production logging tools must be run into wells through casing-tubing annulus, very small diameters of the tools makes it very difficult to measure the flowrate and watercut accurately.
In Daqing Oilfield, the oil production is conducted by means of selective injection into individual zones and the injected fluid is flowing into formation behind the water injection mandrels, which makes the conventional contact method can not be used for measuring the water intake profiles at each injection allocation zone. For this reason, the logging technique is difficult to be developed for measuring fluid injection profiles.
Daqing Oilfield development is now at the stage of tertiary oil recovery, polymer flooding, three component (polymer, alkli and surfactant) combination flooding (ASP flooding) and foam flooding will be the main measures for improving the oil recovery efficiency. For the fluid injection wells and oil production wells during tertiary oil recovery period, the fluid in a wellbore has non-Newtonian behavior. The flow in the production well flooded by polymer is an oil, gas, water, and polymer four-phase flow, in which the flow characteristic is very complex. Study of the new monitoring techniques for measuring the two profiles of these wells becomes a new problem.
For the complex problem faced by the two-profile logging, Daqing Oilfield dispatched a lot of research fellow to develop the two profile logging technology. For the fluid injection profile, the radioisotopic water intake profile logging technology, the continuous spinner flowmeter measuring water intake profile logging technology used in generalized water injection wells, and the electromagnetic flowmeter measuring intake profile in polymer injection and water injection wells have been developed. For the oil production profiles logging, various survey techniques, including through tubing-casing-annulus diverter flowmeter, watercut meters and radioactive densimeter were developed for measuring oil/water two-phase flows and oil/gas/water three phase flows. A large-scale multiphase flow experimental facility was constructed which allows carrying out the flow mechanism investigations, logging tool researches and tool calibrations.
