Sulfate tracer agent for tertiary oil recovery and preparation method of sulfate tracer agent

Abstract

The invention provides a sulfate tracer agent for tertiary oil recovery and a preparation method of the sulfate tracer agent. The tracer agent is composed of inorganic salts capable of achieving color development with ferric ions and a sacrificial agent adsorbed by a preferable ground layer. The tracer agent is good in adaptability and selectivity and high in testing resolution and will not damage environment or harm health of operators. The sulfate tracer agent for tertiary oil recovery comprises ammonium thiocyanate, a heavy metal chelating agent, a pH value modifier, a wetting agent and water by mass percent. The pH value modifier is one of sodium bicarbonate and disodium hydrogen phosphate or the mixture of the sodium bicarbonate and the disodium hydrogen phosphate. The wetting agent is nekal BX or Morwet EFW. The preparation method of the sulfate tracer agent for tertiary oil recovery comprises the steps that on the stirring condition, the ammonium thiocyanate and the heavy metal chelating agent are evenly mixed with water according to a certain ratio, the wetting agent is added for continuous stirring, finally, the pH value modifier is added to adjust the pH value to range from 7 to 10, and after natural settling for 0.5-1 hour, a working solution of the tracer agent is obtained.

Description

Technical field: [0001] The invention relates to the field of petroleum industry chemicals, in particular to a sulfate tracer for tertiary oil recovery and a preparation method thereof. Background technique: [0002] A tracer is a chemical agent that can flow with a fluid to indicate the presence, direction and speed of the fluid. Oilfield water injection tracer technology is one of the on-site production test technologies. Its principle is to inject tracer from the injection well, and then take samples from the surrounding production wells according to certain sampling regulations, monitor the output, and analyze the samples to obtain tracer production curve, and then fit it to reflect the connectivity of oil and water wells during water injection development, and to grasp the direction of water injection, displacement speed, swept area, reservoir heterogeneity and remaining oil saturation distribution, etc. So as to guide the design of oil well production and the adjustme...

AI Technical Summary

Problems solved by technology

However, with the gradual expansion of the application scope of polymer flooding and weak gel flooding, the quality of formation water has changed greatly in recent years, which affects the detection and analysis of chemical tracers and causes large errors. The cost of the tracer is high, the adaptability and selectivity are poor, the test resolution is low, and it will endanger the environment and the health of operators

Although the isotope tracer has the advantages of less dosage, convenient detection and high detection resolution, it will bring serious harm to the safety of personnel and the environment due to its radioactivity.

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