Numerous challenges exist in Total's Central Graben Area (CGA). The main reason being that they present extremely "hard" conditions: high temperature (with 195°C to 225°C due to reverse Joule Thomson effect), high pressure (with 1,100 bar), high salinity (with more than 250g/L in TDS, more than 20g/L in calcium and circa 450mg/L in iron) along with several scale types (with sodium chloride, calcium carbonate, zinc sulphide and lead sulphide). In the wells of CGA fields, the highest scaling risk is the formation of sulphide scale in the subsurface safety valve region. Commercially available scale inhibitors have proven incapable to perform under such "hard conditions" (see SPE 173761). This paper describes the design process of suitable new chemicals (scale inhibitors and nanoparticles scale inhibitors) for both downhole continuous injection and squeeze treatment applications. Such compounds are based on cationic polymers and sulphonated anionic polymers. A chemical approach has been used for the synthesis of silica nanoparticles. The sol-gel method, in addition to its low cost, allows controlling both the size and morphology of the particles by varying certain parameters of the reaction. Extensive laboratory tests have been performed for the validation of these products; these tests include scale inhibitor/brine compatibility, static and dynamic tests, thermal ageing, post ageing analysis and performance tests as well as coreflood tests using real core from the CGA formations. These laboratory testing have allowed the tuning of the chemical design of these novel products in order to improve the performance and the thermal-stability. This paper describes the considerable advancement in chemical performance under these extreme conditions, including specific test development for lead sulphide which has to date proven more difficult than other sulphide scales to assess under field representative conditions in the laboratory. The newly developed chemicals are now ready for trial on the field.

Five Tb3+/Eu3+ mixed nonanuclear clusters with the general formula [Eu9–xTbx(acac)16(µ3‐OH)8(µ4‐O)(µ4‐OH)] ([Eu9–xTbx], x = 0.9–8.1, acac = acetylacetonate) were synthesized. Characterization by powder X‐ray diffraction (PXRD), energy‐dispersive X‐ray spectroscopy (EDS) and inductively coupled plasma optical emission spectroscopy (ICP‐OES) highlight a near‐perfect match between the amounts of Tb3+ and Eu3+ ions input in the reaction mixture and the amounts in the clusters. The luminescence properties of these [Eu9–xTbx] clusters were investigated thoroughly in the solid state, and a strong energy transfer from the Tb3+ to Eu3+ emitters was evidenced. Thus, these nano‐nonanuclear 4f clusters, which can be viewed as square pyramids that share one top, exhibit dual luminescence that can be adjusted by controlling the ratio of the lanthanide ions within the crystal architecture.

Inhibitor products have been widely used to reduce both steel corrosion and scale deposition on pipelines, tubings and safety valves in critical offshore sites. Their simultaneous injection with brine has gradually increased the lifetime of production wells with incontestable benefits for the oil and gas industry. However, the large use of such additives has not been followed by the development of any efficient technique of dosage that considers the strict requirements of an offshore platform. In this paper, we describe a novel method of chemical dosage that takes into account all the on-site technical and practical parameters, such as the quantification thresholds or molecule specificity, the real-time monitoring, the resistance and compactness of measurement device and a user-friendly interface of measurement. Current techniques of inhibitor monitoring that use elemental analysis (ICP, MS, …) for sub-ppm quantifications appear too complex for a successful long-term on-site industrial exploitation due to the bulky dimensions of apparatus and the delay and complexity of analysis. A long-term collaboration between University of Lyon and Total EP has defined a simple and accurate method for inhibitor monitoring based on the use of lanthanide tracers and the Time-Resolved Fluorescence (TRF) technique. We exploited the fact that inhibitor chemicals (i) are good chelators for lanthanide ions and (ii) amplify the luminescence signal of rare-earths. In this way we are able to collect the photon emission signal by TRF apparatus and dosing the inhibitors. The portability of the TRF device as well as the sensitivity of detection have been engineered in order to obtain a sub-ppm quantification threshold via 1-click task. Several carboxylates, phosphonates and sulphonates additives diluted in brine solutions has been easily measured out even in presence of residual oil. More than 20 commercial inhibitor solution samples were quickly prepared and dosed with an impressive linearity of response (R2 test > 0.996) in the 10 – 100 ppm range. Any further extension of range has been possible. In addition, we were able to quantify two inhibitors (scale – scale, scale – corrosion) in the same brine water. This technique certainly opens a new conception of smart chemicals management in oil and gas production for (i) a dramatic minimization of the injected compounds (ii) a reducing delay in pipelines monitoring, and (iii) a shut down of expenses of pipeline maintenance.