The present set of RILEM recommendations specifies test methodologies for determining the different mechanical properties of concrete at high temperatures. It applies to all types of concrete used in *The text presented here is a draft for general consideration.

Water production control is a key issue in most mature reservoirs worldwide. Many techniques have been developed to achieve this purpose. Water Shut-off (WSO) treatments using crosslinked gels have proven to be an effective alternative. When appropriately designed and applied, these systems generate flow restrictions in high permeable or fractured formations that bypass water from highly saturated zones (injection water or natural brines). WSO treatments efficiency depends on several aspects as reservoir fluids flow patterns, rock petrophysics, formation heterogeneity, and WSO gel characteristics. This last aspect is adjusted to optimize the treatment based on experimental tests performed in the laboratory. This paper presents an experimental methodology to evaluate and adjust WSO polymer systems according to operational and treatment performance requirements. These studies go from qualitative gel consistency and fluid compatibility bottle tests, to rheological characterizations to determine viscosity variations and gelation time (outside porous media tests), as well as flow tests performed on formation and Berea core plugs at reservoir conditions (inside porous media tests). These properties are highly important to avoid early gelations and, at the same time, assure the appropriate WSO placement in the reservoir. Viscoelastic properties such as G* (complex modulus), G′ (storage modulus) and G″ (loss modulus) define the gel strength and provide structural information such as crosslinking density. These parameters are essential to design the gel formulations (polymer and crosslinker type and concentration) depending on the operational and reservoir requirements. Finally, the flow tests performed on core plugs show the changes in water and oil permeability after injecting the treatment. This information is used to calculate the residual resistance factors to water (RRFw), oil (RRFo) and the gel resistance index (GRI). These parameters define the treatment blockage degree and allow estimate probable well production response as well as the best production regimes to extend the treatment life time. This methodology was applied on a new WSO gel system, developed for a wide range of applications. The effect of polymer concentration, temperature, salinity and flow rate are examined in detail. Experimental tests are many times underestimated when planning a WSO job; however these tests will always provide valuable information that will increase the chances of successful water shut-off treatments. The connection between laboratory and field parameters and its influence in the oil and water productivity were analyzed.

No abstract

The use of Glass Reinforced Epoxy (GRE) casing has increased significantly during the last decade, primarily on secondary recovery water injector wells. Corrosion resistance is this material main advantage when compared to steel. Almost one hundred wells have been completed in the Neuquén basin, Argentina, during the past five years.This paper presents the experience obtained after cementing and completion of 70 GRE cased wells. Improvements on cement slurry mix designs, mud cleaning preflushes systems and best practices to ensure successful stimulation conditions (acids and fractures) are provided.The work is supported by a laboratory study focused on the GRE casing to cement bonding performance evaluation and a finite element numerical simulation analysis of the down-hole service conditions achieved during stimulation jobs. This study considered the influence of GRE, cement and rock mechanical properties, the mud-cake removal conditions, as well as different bonding conditions. A comparison between GRE and steel cased wells is presented.Cementing results were improved by casing centralization, increasing the preflushes aggressiveness and using low density slurries. Bonding experimental results showed that original GRE external coating attempts against cement bonding strength.The numerical simulations show that when GRE casings are subjected to high internal pressures, its elastic behavior (Young modulus ten times lower than steel) generates overloading on the cement annulus. This condition could generate cracks that will propagate along the annulus creating communications paths between close perforated zones during stimulations treatments. This situation is even worst when poor formation mud-cake removal takes place.

No abstract