Cultured skin equivalent (SE, Mimeskin) was generated by co-culturing skin fibroblasts and keratinocytes on a collagen-glycosaminoglycan-chitosan dermal substrate. In order to examine donor age effect, fibroblasts from 19- (young) or 49- (aged) year-old females were used. Culture medium was supplemented with nutrients complex containing soy extract, tomato extract, grape seed extract, white tea extract, sodium ascorbate, tocopherol acetate, zinc gluconate and BioMarine complex. Epidermal and dermal structure and composition were examined after 42 and 60 days of culture. In untreated samples, SE generated from young fibroblasts was superior to SE from aged fibroblasts in all characteristics. Those include number and regularity of keratinocyte layers, number of keratinocytes expressing proliferation marker Ki67, content of collagen type I, fibrillin-1, elastin, and SE lifespan. Effects of nutritional supplementation were observed in SE from both young and aged fibroblasts, however, those effects were more pronounced in SE from aged fibroblasts. In epidermis, the treatment increased number of keratinocyte layers and delayed epidermal senescence. The number of cells expressing Ki67 was nine folds higher than those of controls, and was similar to that of young cell SE. In dermis, the treatment increased mRNA synthesis of collagen I, fibrillin-1 and elastin. In conclusion, skin cell donor age had major important effect on formation of reconstructed SE. Imperfections in epidermal and dermal structure and composition as well as life span in SE from aged cells can be improved by supplementation with active nutrients.

The Céré-la-Ronde underground gas storage reservoir in the Paris Basin, a test site to study and enhance reservoir seismic monitoring, is a water-bearing sandstone reservoir in a faulted anticline structure. Seismic data acquired so far have generated a qualitative interpretation of the location of the gas bubble by studying fluid saturation (Meunier, 1998). However, between 1994 and 1997, two sonic logs showed subtle differences in V P not explained solely by saturation variations. Changes in pore pressure and stresses also influence reservoir elastic properties. Hence, we used geomechanical modeling to evaluate quantitatively how exploiting the gas reservoir impacts seismic measurements.Our method begins by computing, in a reservoir simulator, pore pressure and saturations. Pore pressure is a key input in the geomechanical modeling that produces mean effective stresses. These and the saturations are used to update seismic velocities in accordance with rock physics theory. In the final step, the introduction of a wavelet allows seismic modeling and the study of seismic attributes.Modeling. The reservoir simulation uses a 3-D finite volume code. The model covers 336 ǂ 228 km 2 . The key level of the reservoir model is split into three reservoir layers. R1 is used for gas storage. R2 and R3 are separated by shaly layers. A 2-D section was extracted from the 3-D model for the geomechanical modeling and overburden and underburden layers were added because the model has to cover the whole geologic column from the surface to a depth of 1500 m ( Figure 1).Geomechanical properties of each layer are extracted from core measurements (when available), sonic logs, or using characteristics of analogs. Initially, vertical stresses are determined by rock densities and horizontal stresses by an estimated stress ratio. The initial pore pressure is constant. The load for the geomechanical modeling is determined from cycling variations of the pore pressure in the reservoir (computed by the reservoir simulation). Our modeling has no lateral displacement at external boundaries. Figure 2 shows the results of the geomechanical modeling (i.e., pore pressure and mean total stresses variations) at well A for different production times. Mean effective stress (σeff) is defined as difference between mean total stress and pressure.Rock physics models are used to evaluate the impact of mean effective stresses on effective bulk modulus. We use contact models based on Hertz-Mindlin contact theory (Mindlin, 1949). In this technique, two identical spherical grains of radius R are deformed by normal and tangential forces. The radius of the contact area is a function of σeff, meaning effective shear and bulk moduli are also linked to mean effective stress. Using both moduli, V P and V S may be computed. Hertz-Mindlin theory assumes that velocity varies with σeff raised to the 1/6 th power. Some laboratory measurements on samples gave a smaller exponent: 0.09 for V P and 0.13 for V S . If the initial velocity (V 0 ) is known, the new velocity (V 1 )...

Seismic measurements acquired at different stages in the life of a reservoir can monitor the fluid distribution over production time. Changes in saturation, pore pressure and stresses, induced by reservoir production may influence the process of wave propagation in rocks. The variations in mean effective stresses, due to changes in mean stress or /and pore pressure, are not always integrated in a proper manner. We present here a methodology to evaluate what is the contribution of a geomechanical approach on the computation of seismic velocities. This methodology has been used for the monitoring of an underground gas storage site of Gaz de France, the French gas Supply Company. Successful results illustrate the importance of integrating geomechanics with geophysics to validate real sonic data from DSI. Introduction Seismic monitoring (time-lapse or 4D) has emerged as one of the most important technical developments in the oil and gas industry for this decade. This technique has the potential to significantly enhance recovery and optimize exploitation schemes in existing and new fields. It aims at monitoring -by repeated VSP, 2D or 3D seismic surveys- seismic changes, velocity and density, related to fluid, stresses and temperature changes during the production of a field. Changes in density and velocity result in impedances changes which, under favorable conditions, can be detected in seismic data. The probability of success of the technique heavily depends on many factors, like reservoir parameters (depth, rock and fluid properties, pressure, …), nature of the recovery processes and the repeatability of the different seismic surveys1. A careful feasibility study on the field of interest, coupled with a clear reservoir objective, is required to give a realistic estimate of what seismic monitoring can provide for reservoir management. The Céré-la-Ronde underground gas storage reservoir, in the Paris Basin, is used as a test site to study and improve reservoir seismic monitoring methods (Fig. 1). It is a water-bearing sandstone reservoir in a faulted anticline structure. The depth of reservoir is about 900 meters and its thickness is about 25 meters, at the structure top (Fig. 2). Regarding seismic monitoring, the site presents favorable characteristics -shallow reservoir and gas injection process1-, and unfavorable ones -low repeatability due to unpredictable statics-. The different repetitive acquired data (DSI, VSP, walk-away and 2D seismic) allow so far a qualitative seismic interpretation of the gas bubble location, by studying fluid saturation influence2. However, between 1994 and 1997, two DSI logs show subtle differences on Vp velocity not explained by saturation variations only. Changes in pore pressure and stresses also influence the computation of seismic velocities. Hence, using geomechanical modeling, we want to evaluate in a quantitative way, how the gas reservoir exploitation influences the seismic measurements. Several previous studies have shown the interest of using both fluid saturation and pore pressure to interpret time-lapse seismic data3,4. In all these works, when the influence of mean effective stress on seismic velocities is studied, only pore pressure is considered and mean total stress is seen as constant. Usually, stresses evolve during reservoir exploitation. In our approach, using geomechanical modeling, we will consider variations in the mean effective stresses, induced by changes in both the mean total stresses and pore pressure distribution. This paper presents a methodology developed in order to integrate geomechanical modeling in the calculation of seismic velocities. This implies to combine geomechanics with geophysics. The implementation of this method is composed of three steps. In step1, in order to take into account multiphasique fluid flow, pore pressure and saturations are computed by a reservoir simulator. Then, the computed pore pressure is used as a load in the geomechanical modeling, (step2). In step3, the results of the geomechanical modeling (mean effective stresses) are used to compute the drained bulk modulus (Kd) and the shear modulus (µ), using rock physics.

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