Different types of tracers were added to each section of fracturing fluid, and the concentration change of tracer in the flowback fluid was monitored by intensive sampling during the flowback after fracturing.

Fracture analysis : fracture number, fracture morphology ( main fracture, micro fracture, volume fracture, etc. )

(1) The proportion and contribution of each layer of output；

(2) Changes of oil and water produced in each layer；

(3) well connectivity；

(4) Fracture morphology : main fracture, micro fracture, volume fracture, etc.

(5) Correlation between formation physical properties and productivity

technology introduction：

(1) Trace elements are ' loaded ' into nanocapsules to prevent metal ions from contacting with other substances.；

(2) Nanocapsules are encapsulated into ' microspheres ' by lipophilic polymer.；

The synthesized trace element tracer has good water / oil solubility. Acid resistance, alkali resistance, stable properties. Heat resistance 240℃. It has excellent chemical inertness, no chemical reaction with most organic and inorganic substances, and very little formation adsorption.