Microelement tracer agent used for offshore oilfield and use method thereof

Abstract

The invention provides a microelement tracer agent special for an offshore oilfield. The tracer agent is made from raw materials of a precursor and a post-cursor. The precursor and the post-cursor each contain microelement chloride. A microelement mixture is a praseodymium-molybdenum chloride mixture. The invention further provides a use method of the microelement tracer agent. The use method comprises the step that a prepared precursor solution and a prepared post-cursor solution are sequentially injected into a monitoring well, wherein the volume ratio of the precursor solution to the post-cursor solution is 1:(0.8-1), and the time interval for injection of the precursor solution and injection of the post-cursor solution is 80-120 min. The prepared microelement tracer agent is free of radiation and pollution and good in safety and stability; an HR-ICP-MS instrument is used for detecting, the minimum detection limit can be up to 10-15 (ppq grade) grade; and the microelement tracer agent can be fast disintegrated in water, and evenly diffused and dissolved with the diffusion time no longer than 48 seconds.

Description

Technical field [0001] The invention relates to a tracer and a use method thereof, and more specifically, to a trace element tracer for offshore oil fields and a use method thereof. Background technique [0002] Water injection tracing technology is one of on-site production testing technologies. The principle is to inject the tracer from the injection well, and then take samples from the surrounding production wells according to certain sampling regulations, monitor the production situation, analyze the samples, obtain the tracer production curve, and then perform fitting to reflect the water injection The connection of oil and water wells during development. Master the direction of the injected water, the displacement speed, the affected area, the heterogeneity of the reservoir and the distribution of remaining oil saturation, etc. to guide the design of oil well production and the adjustment of the later stage of oil field development. [0003] At present, water injection deve...

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Problems solved by technology

[0006] 1. Due to the long-term water injection in the oil layer, the stability of fractures in the enhanced rock formation decreases, the dissolution of soluble salts increases, and the expansion of cracks directly leads to the formation of large pores;

[0007] 2. The tracers in the prior art are non-radioactive, polluting, and not good enough in safety and stability;

[0008] 3. The tracers in the prior art have insufficient analytical precision;

[0009] 4. In the prior art, the tracer in China has a long diffusion time in water

[0010] Due to the above defects, the oil recovery efficiency is low, the oil yield is low, the amount of water-free treatment is large, and the cost of oil production is increased. The present invention is proposed for the above-mentioned defects of the prior art.

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