| A tight reservoir always requires hydraulic fracturing before production to increase production rate. The additives in hydraulic fluids are highly considerable for a successful stimulation. A friction reducer is often used to reduce the flowing friction in the wellbore during hydraulic fracturing. Extensive researches have been conducted to examine the extent it can reduce the fluid friction in tubings; however, no research has been reported on its behavior in a reservoir, which is related to the fracture extension. A breaker is also pumped into the formation to degrade the friction reducer. However, it is not clear that what is the best time to break it. After the hydraulic fracturing, the existence of liquid in matrix reduces the gas phase permeability. A surfactant is added to reduce water block by providing a low surface tension. However, the effect of the surfactant on the petrophysical properties of tight rocks is not clear.;In this dissertation, the following four researches have been carried out, and significant findings have been summarized in conclusions. The friction reducer flow behavior in microfractures was studied firstly, including size effect, concentration effect, wettability effect, and etc. Consequently, various additives impact on the petrophysical properties on tight sand was examined, such as surface contact angle, gas phase permeability, liquid imbibition, and gas transportation. Then, formation damage of FR and breaker in tight sand was systematically investigated. The impact factors were disclosed in detail, including fluid concentration, sample length, breaking time, and permeability regain. Finally, surfactant wettability impact on liquid intake in shale was carried out carefully. The liquid intake rate affected by the existence of fractures, fluid concentration, sample length, and treatment method were specified in detail. |
