Solving the problem of the low temperature and low salt resistances of conventional polyacrylamide and the high cost of functional monomers, and thus, introducing it to the interlayer space provided by a layered structure for polymer modification, is a promising option. In this study, montmorillonite was used as the inorganic clay mineral, and an intercalated polyacrylamide/clay nanocomposite was synthesized via in situ intercalation polymerization. The optimal synthesis conditions were a clay content of 10.7%, preparation temperature of 11 °C, initiator concentration of 2.5 × 10−4 mol/L, and chain extender concentration of 5%. The IR results showed that the polymer was successfully introduced to the nanocomposite. The synthesized intercalated polyacrylamide/clay nanocomposite exhibited a better thickening effect, good viscoelasticity, and better salt resistance and thermal stability than polyacrylamide. In addition, the thickening capacity and thermal stability were superior to the salt-resistant polymer, with a 16.0% higher thickening viscosity and a 15.1% higher viscosity retention rate at 85 °C for 60 d. The intercalated polyacrylamide/clay nanocomposite further expanded the application of polyacrylamide in petroleum exploitation.

This paper developed a new methodology for rate transient analysis of fractured wells in carbonate reservoirs. Both the heterogeneity and dual-permeability flow behavior are incorporated into the proposed model, and the fractured carbonate reservoir was simulated with a two-zone composite model. In each zone, a traditional dual-porosity model was applied to describe the characteristics of the natural fractures and matrix. With the Laplace transform, we derived the solution of the mathematical model and plotted new type curves for transient rate decline analysis. Then, the flow regimes were divided and analyzed based on the new type curves. The influences of several critical parameters on transient rate response were also examined. A field case was studied further to demonstrate the precision and application of the proposed method. The results show that the new type curves are mainly composed of eight flow stages. The difference in physical properties (k 2,1 , η 2,1 ) between the two zones significantly impacts the transition and boundary-dominated flow regimes. When the values of k 2,1 and η 2,1 are smaller, the derivative curve of the transition flow stage will move down, and the duration of this stage on the derivative curve is longer, while the duration of the boundary dominant flow stage will decrease. The dimensionless radial radius of the inner zone (r 1D ) can significantly influence the transition flow regime. When r 1D is larger, the production rate and its derivative curve of the transition flow stage will move up, and the duration of this stage will be longer. The results also show that the proposed methodology can effectively fit the field production data. This method can be applied in well productivity evaluation for fractured carbonate reservoirs.

Soft Microgel (SMG) used to enhance oilfield recovery is a kind of aqueous dispersion chemical agent system of microgel particles. It is usually used in medium and low permeability reservoirs and is generally not used for plugging large pores of reservoirs due to the limitation of particle size. To resolve the problem that SMG cannot effectively block large pores of the reservoir, the multi-functional system (SMG-w) can be synthesized by introducing inorganic components into SMG under special conditions. The main physical and chemical properties of SMG-w are carried out in the laboratory. The results of the study show that SMG-w has an excellent resistant ability to temperature and salinity. Besides, it can also decrease the interfacial tension of oil and water. What’s more, it can react with Ca2+ or Mg2+ in formation water from a large number of flocs in the high salinity reservoir, which can enhance physical and chemical properties of SMG-w and make it be applied in deep profile control of high permeability reservoirs with high temperature and high salinity.