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While polymer flooding has proven to be an effective technique to improve oil recovery from mature reservoirs, the new objective pursued by the main stakeholders consists now in optimizing the overall costs and decrease the risks associated to the implementation of chemical enhanced oil recovery methods. This is particularly true for reservoir conditions with high temperatures (above 85°C) using injection brine with high hardness.In such conditions, using specific robust polymers is necessary to ensure stability over months during propagation in reservoirs. These polymers containing Acrylamido-Tert-Butyl-Sulfonate (ATBS) and N-Vinyl Pyrrolidone (NVP) are more expensive than regular HPAM and have to be overdosed to reach target viscosities since their molecular weights are low. In extreme cases, the project can be aborted for economic reasons. However, many fields, especially in South America, have access to very soft injection brines with a total dissolved salt lower than 3000 ppm in many cases. Using such brine is a tremendous advantage for polymer flooding since less robust polymers can be selected and target viscosity can be achieved with low dosages. This paper describes the selection and evaluation of polymers dedicated to high temperature reservoir conditions (from 85°C to 140°C) using very low salinity brine in comparison with harder brine. A series of rheological, shear and thermal stability tests have been performed to select the most appropriate polymer for each case. The impact of the chemical composition and the microstructure shows that the incorporation of NVP is not necessarily required to ensure stability over 6 months above 100°C in soft brines. Results show as well that ATBS improves shear and thermal stability in both soft and hard brine conditions. Besides, the incorporation of thermo-responsive moieties in the polymer improves viscosity properties resulting in a lower dosage even at high temperature to reach target viscosity.The objective of the study is also to demonstrate the possibility to develop innovative and cost-effective polymers for each reservoir condition. It encompasses an early and particularly close cooperation between the polymer manufacturer and the company willing to improve oil recovery from its reservoirs.

The performances of new microgels specifically designed for water shutoff and conformance control were extensively investigated at laboratory scale. These microgels are preformed, stable, fully water soluble, size controlled with a narrow size distribution, and non-toxic. They reduce water permeability by forming adsorbed layers soft enough to be very easily collapsed by oil-water capillary pressure, so that oil permeability is not significantly affected. Since the manufacturing process of these new microgels make possible to vary chemical composition, size and crosslink density, they can be designed as desired to meet the requirements of a given field application. The laboratory results reported in this paper concerns mainly three microgel samples having significantly different crosslink densities. We describe the relevant laboratory methods used to determine main microgel characteristics. The microgels have remarkable mechanical, chemical and thermal stability. Their behavior in porous media have been investigated extensively, showing that:their propagation distance is only limited by the volume injected,their injectivity is facilitated by a shear-thinning behavior andwater permeability reduction can be achieved as desired by controlling the thickness of adsorbed layer. Thus, this new microgels, now available at industrial scale, look as very promising tools, not only for water shutoff but also for conformance control in heterogeneous reservoirs. Introduction Background In a global context of growing energy needs with a perspective of depletion of oil and gas resources, extending the life of hydrocarbon reservoirs is a real challenge for the decades to come. In that situation, as well as for environmental reasons, reducing significantly water production and improving oil recovery efficiency is an important goal for oil industry. Thus the development of more reliable techniques using "green" products for water-shutoff, conformance, and mobility control is of crucial interest. Among the methods available to reduce water production [1], injecting a gelling system composed of a polymer and a crosslinker has been widely used [2–5]. In this process, the gel is formed in-situ. Since gelling properties have been found to depend on many factors [6–11], the gelling time, the final gel strength and also the depth of the gel penetration is quite difficult to predict. This difficulty results from the uncertainties concerning different factors: shear stresses both in surface facilities and in near-wellbore area and also physico-chemical environment around the well (pH, salinity and temperature). Moreover, both polymer and/or crosslinker adsorption in the near-wellbore region and dilution by dispersion during the placement can affect the effectiveness of the treatment. To overcome these severe drawbacks, different authors have recently proposed new methods, aimed at improving the process by injecting preformed gels particles or dilute gelling systems. Bai et al. method [12,13] consists in drying, crushing and sieving polymeric gels prior to injecting them. Mack et al. [14,15] method consists in obtaining "colloidal dispersion gels" (CDG) by crosslinking low concentration polymer solutions with low amounts of chromium acetate or aluminium citrate. This process slows down the gelation kinetics, so that, on a well injection time scale, those systems only form separate gel bundles, thus making possible to enter the matrix rock. However, the in-depth propagation of these two of gels remains questionable. In 1999, Chauveteau et al. introduced [16] a completely new concept which consists of injecting fully water soluble, non-toxic, soft, stable and size-controlled microgels into the reservoir. A first type of microgels, using an environmentally friendly zirconium crosslinker, has been extensively studied in the past years, regarding both the understanding of gelation mechanisms and the transport properties in porous media [16–23]. More recently, a second type of microgels, which are covalently crosslinked, was introduced [24]. These microgels, now available at industrial scale, have been shown to have very attractive properties for both water shutoff and conformance control operations.

The present paper describes the first field application of a new water shutoff technology using size-controlled microgels for the treatment of a gas storage well. The treatment was designed from an integrated study combining laboratory coreflood experiments and near-wellbore reservoir simulations. The candidate well (open hole completion with liner) was drilled in a sandstone reservoir formation made of a succession of layers with different petrophysical quality all connected each other. The presence of a thin high-permeability streak located in the bottom part of the open interval was assumed to be the main factor of excessive water production. A bullhead option was chosen for the treatment. Microgel size (around 2 micron) favored their placement in the high-permeability layer, whereas the penetration in the rest of the reservoir was expected to be very superficial. The treatment was performed in June 2005. Due to pressure constraints, the volume of the treatment had to be reduced to 26 m3 only. A backflush of gas was necessary to recover gas injectivity. The well was kept on production during the whole winter season 2005–2006. Water production was significantly reduced thus enabling higher gas rate production. A positive impact on sand production was also observed. Well behavior was in good agreement with model predictions. Introduction Water intrusion from aquifer in underground gas storage wells affects well performances more especially when the Gas-Water Contact is high in the reservoir and the gas rates due to peaks of demand are intense. Some pioneer field operations have shown that polymer technology can be an efficient way to solve this problem.1,2 The principle of the treatment is shown in Figs. 1 and 2. The polymer injected into the open interval invades the different layers surrounding the wellbore with a deeper invasion of the higher permeability layers, which are frequently the main water producing zones. This type of product adsorbs on the formation rock almost irreversibly and induces a selective reduction of the relative permeability to water with respect to the relative permeability to oil or to gas. This unique property of water soluble polymers and gels is well documented in the petroleum literature, as "RPM" (Relative Permeability Modification) or "DPR" (Disproportionate Permeability Reduction). Indeed, although the origin of this phenomenon remains controversial, there is a large consensus about the reality of this property, which has been observed during either water/oil or water/gas two-phase-flow coreflood experiments with many different core materials and polymer/gel species.3–12 The combination of a polymer/gel favorable placement in the water-producing layers together with RPM effect induces lower water cut production after treatment. If the loss of Productivity Index can be compensated by higher drawdown, the treated well can produce more oil or more gas. Liang, Lee and Seright pointed out that RPM effect is not enough to guarantee a successful treatment, especially in radial flow conditions.13 In fact , a perfect RPM product, which reduces the relative permeability to water without inducing any change in the curves of relative permeability to oil or to gas, may affect the effective permeability to oil or to gas through an increase in water saturation. This occurs when the fractional flow of water from the oil producing layers is significant. The water blocking effect increases with the depth of penetration of the polymer/gel in the layer and with the intensity of the permeability reduction to water. Therefore, preventing a deep penetration of RPM products into the oil/gas layers can be considered as mandatory to achieve a good water shutoff treatment.

While polymer flooding has proven to be an effective technique to improve oil recovery from mature reservoirs, the new objective pursued by the main stakeholders consists now in optimizing the overall costs and decrease the risks associated to the implementation of chemical enhanced oil recovery methods. Several options do exist to tackle these challenges. Developing more costeffective polymers is one of these. Traditional partially hydrolyzed polyacrylamides (HPAM) are sensitive to brine hardness and temperature; increasing both lead to a drop in viscosity which could be detrimental to the success of the project. As a result, it is generally necessary to increase the dosage of the HPAM to reach the targeted viscosity and balance for the viscosity drop induced by polymer collapse, but always at the expense of the economics of the project. In extreme cases, the project can be aborted for economic reasons. This paper describes a new class of polymers, called “stimuli-responsive”, which has been designed to overcome the aforementioned challenges. This new family of polyacrylamide-based polymers has structurally modified to counterbalance the negative effect of salinity and temperature encountered during the transit through the reservoir. The placement, number and quantity of stimuliresponsive grafts can be finetuned to each reservoir condition to develop its full potential in the subterranean formation. This variable comes on top of other possible adjustments made to the polymer backbone including molecular weight, hydrolysis and incorporation of thermostable groups such as ATBS (acrylamide tertio butyl sulfonic acid) and/or NVP (Nvinyl pyrrolidone). A series of rheological tests has been performed to demonstrate several features of the solutions prepared from these polymers, including salinity resistance, effect of temperature and longterm stability tests. Moreover, injectivity and retention tests have been performed to evaluate the behavior of these polymers in porous medium. A reduction in the polymer dosage on the injection side and the stimuli responsive behavior of the polymer also open new opportunities to minimize the impact of the presence of said polymer in the coproduced water on surface facilities. Some preliminary experiments have been performed in these directions. The objective of the study is also to demonstrate the possibility to develop innovative and costeffective polymers for each reservoir condition. It encompasses an early and particularly close cooperation between the polymer manufacturer and the company willing to improve oil recovery from its reservoirs.

Humankind is facing a climate and energy crisis which demands global and prompt actions to minimize the negative impacts on the environment and on the lives of millions of people. Among all the disciplines which have an important role to play, chemistry has a chance to rethink the way molecules are made and find innovations to decrease the overall anthropic footprint on the environment. In this paper, we will provide a review of the existing knowledge but also recent advances on the manufacturing and end uses of acrylamide-based polymers following the “green chemistry” concept and 100 years after the revolutionary publication of Staudinger on macromolecules. After a review of raw material sourcing options (fossil derivatives vs. biobased), we will discuss the improvements in monomer manufacturing followed by a second part dealing with polymer manufacturing processes and the paths followed to reduce energy consumption and CO2 emissions. In the following section, we will see how the polyacrylamides help reduce the environmental footprint of end users in various fields such as agriculture or wastewater treatment and discuss in more detail the fate of these molecules in the environment by looking at the existing literature, the regulations in place and the procedures used to assess the overall biodegradability. In the last section, we will review macromolecular engineering principles which could help enhance the degradability of said polymers when they reach the end of their life cycle.

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In order to be more extensively used outside of research laboratories, lab-on-chip technologies must be mass-produced using low-cost materials such as thermoplastics. Thermoplastics, however, are generally hydrophobic in their native state, which makes them unsuitable for direct use with biological samples in aqueous solution, and thus require surface coating. This coating should be robust, inexpensive and simple to implement, in order not to hinder the industrial advantage of thermoplastic chips. Cyclic Olefin Copolymer (COC) is a particularly appealing polymer, but it is also difficult to functionalize due to its chemical inertness. Here we introduce and compare the performance of two new approaches for COC coating. One relies on the use of a commercial triblock copolymer, Pluronic® F127. The second approach uses new copolymers synthesized by radical polymerization, and consisting of a dimethylacrylamide (DMA) backbone carrying aliphatic side chains (C22). Two DMA-C22 copolymers were synthesized with various C22/DMA ratios: DMA-S at 0.175% and DMA-M at 0.35%. Different physicochemical properties of the polymers such as critical micellar concentration (CMC), water contact angle, electroosmosis were investigated. Coated COC chips were then tested for their ability to reduce the adsorption of proteins, microparticles, and for protein electrophoresis. For each application we found an optimal treatment protocol to considerably improve the performance of the thermoplastic chip. These treatments use physisorption in situ which requires no photografting or chemical reaction and can be performed by a simple incubation either after chip production, or just prior to use.