Experimental Study of Synergy between Polymeric Microspheres and Nanoemulsions for Profile Control and Water Plugging.

The development of low-porosity and low-permeability oil reservoirs in the Changqing oilfield presents a significant challenge due to the high injection pressure and limited space for profile control and pressure raising. Therefore, the synergistic profile control and flooding technology of polymer microspheres (PMs) and nanoemulsions is proposed, which makes use of the plugging performance of PMs and the pressure-reducing and oil-driving properties of nanoemulsions, with the objective of controlling the water-absorbing profile and increasing the recovery rate. The paper assessed the properties of nanoemulsions and PMs and evaluated their suitability for reservoirs.

Experimental Investigation of a Novel Nanocomposite Particle Gel for Water Shutoff Treatment in Mature Oilfields.

Conventional preformed particle gels suffer from insufficient salt tolerance and weak mechanical properties after water absorption, which reduce the water shutoff effect in mature oilfields. In this paper, a nanocomposite particle gel (NCPG) is synthesized by copolymerization of acrylamide (AM) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) using laponite RD (LPT) as a physical cross-linker and ,-methylene-bisacrylamide (MBA) as a chemical cross-linker via in situ free radical polymerization. Compared with the NCPG without LPT, both the swelling rate and mechanical properties of NCPG added with LPT are found to be improved.

Consensus Tracking Control of Uncertain Multiagent Systems With Sampled Data and Time-Varying Delay.

In this article, the adaptive consensus tracking control is developed for uncertain multiagent systems with time-varying state delay in the case that leader's state is accessible at sampling instants. By proposing a distributed sampled observer with hybrid form, adaptive tracking controller with the complementary term is designed for first-order multiagent systems, and then is extended to high-order multiagent systems with the aid of dynamic surface control. Through the complementary term, the effects of parameter estimation error as well as dynamical terms with time-varying delays are eliminated and thus less conservative condition on time delays is required.