Influence of Nanoemulsion Droplet Size of Removing Water Blocking Damage in Tight Gas Reservoir

Abstract

During the production process, water phase incursion into the reservoir causes water blocking damage and seriously affects the production of tight gas reservoirs. Recently, nanoemulsions have been used as highly effective water blocking removing agents in the field, but their mechanism is still unclear. In this research, a series of nanoemulsions with different droplet sizes were synthesized, and their water blocking removing performance was intensively investigated. To begin, the relationship between the droplet size and the chemical composition of the nanoemulsion was determined by dynamic light scattering. Second, the influence of the nanoemulsion droplet size on the surface tension and the contact angle experiments was studied. Finally, NMR and permeability recovery experiments were used to study the relationship between the droplet size and the water locking removing effect of the nanoemulsions. Simultaneously, the surfactant release process was investigated using the static adsorption curves of the nanoemulsions. The experimental results show that the droplet size of nanoemulsion has an exponential relationship with the oil phase content. The surface tension decreases with the increase in droplet size, but the wetting reversal effect decreases with the increase in droplet size. The nanoemulsion with an oil phase content of 5 wt.% has the best water locking removing effect, and the permeability recovery value of the core reaches 59.54%. The adsorption control of the nanoemulsion on the surfactant is the key to its water blocking removing ability. This comprehensive study shows that the nanoemulsion with an oil phase content of 5 wt.% has optimum adsorption control capability. Thus, it can be used as a promising candidate for removing water blocking in tight gas reservoirs.

Acid System and Stimulation Efficiency of Multistage Acid Fracturing in Porous Carbonate Reservoirs

“…More obvious [27,28] etching grooves formed after multistage alternating injection of gelled acid and cross-linked guar, cross-linked acid and gelled acid, and cross-linked acid and cross-linked guar. This etched groove greatly enhanced the nonuniform etching degree of the fracture wall [29], which hindered the acid-etched fracture from completely closing under the closing pressure after the acid fracturing stimulation, thus forming a high-speed channel for the flow of oil and gas. The etched grooves formed after the multistage alternate injection of cross-linked acid and diverting acid were more obvious.…”

Interaction between Droplets and Particles as Oil–Water Slurry Components

“…The ranks of coals used as solid substances were chosen from the most common ones in composite liquid fuel preparation [17,25,43]: brown and coking bituminous coal, filter cake of coking bituminous coal and anthracite. One of the key characteristics of solid substances interacting with liquids is their wettability [44]. The hysteresis of the wettability of coal particles is significantly affected by their surface uniformity, roughness and chemical purity.…”

Study and Mechanism Analysis on Dynamic Shrinkage of Bottom Sediments in Salt Cavern Gas Storage

“…Al 30 is composed of two δ-Al 13 connected by four Al monomers. The two-tetrahedral coordinated Al in Al 30 produces wide 27 Al NMR signals at d = 70 ppm. Al 30 has a higher resistance to high temperatures and stronger charge neutralization ability than Al 13 , and it has 18 positive charges and a unique nanomolecular size, making it another promising shrinkage agent besides Al 13 [18].…”

“…In recent years, 27 Al NMR technology has been used for the determination of aluminum morphology in many fields [23][24][25][26][27]. Compared with other methods used for the determination of aluminum morphology, the outstanding advantage of NMR technology is that it can go deep into the substance without destroying the sample, and it will not change the chemical morphology of Al in the measured solution.…”