Well cementing primary

In addition to primary cementing of the casing and liner, there are other important well cementing operations. These are squeeze cementing and plug cementing Such operations are often called secondary or remedial cementing [161]. 

There are two basic oil well cementing activities primary cementing and secondary cementing. 

The cementing technology can be improved in wells with zones containing clays or shales that are sensitive to freshwater cement filtrate. Sodium chloride (i.e., natural salt) and potassium chloride (KCl) have been the primary materials of choice to yield a filtrate that damages these zones less. However, the unfavorable effects of salt on cement have been extensively documented, in particular. 

Although the standard urea-ammonia SCR technology is nowadays well established and used world-wide for the control of NO, from stationary sources, additional applications are predicted in large gas turbines, incinerators, stationary diesel engines and the cement and glass industries in view of the enforcement of stricter emission limits and of the high cost of alternative very efficient primary methods. 

The technology can be nsed for the passive in sitn treatment of groundwater via exchangeable filter socks placed in trenches or wells, or via a cement slnrry injected into the aquifer to form a migration barrier across the plnme of contamination, or as a sonrce control. OCR can also be used in powder form for the in sitn or ex situ treatment of soils. The primary in sitn soil application is the treatment of nndergronnd storage tank (UST) removal excavations. The technology can also be nsed to treat soils in ex sitn biopiles. 

In the Upper Namur Sandstone the poikilotopic calcite cement is absent in moderately to poorly sorted quartz arenites and feldspathic quartz aren-ites that contain abundant primary porosity and some secondary porosity. Only minor patches of siderite micrite and microspar are observed in these elastics, where euhedral quartz overgrowths are well developed, albeit not volumetrically significant (< 5-10%) (Fig. 14D). The detrital grains are dominated by tangential and long contacts, with rare sutured contacts. 

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