Selective zone placement

Are the grout holes laid out in plan and profile Do the holes enter the zone to be grouted Have a sequence and time schedule of hole placement been selected ... 

Given the different factors that we can influence to increase zone coverage, selection of an acid placement method sometimes requires creativity and always requires being open to all options and combinations thereof. With respect to selection of acid placement methods, service company/operator guidelines and charts have proven repeatedly to be of limited use. 

The importance of treatment placement was evident in the earliest acid treatments. In his patent, Frasch noted the need for a ruhher packer for isolation, so that acid could be selectively injected into the formation. Although this need has been recognized from day one, the absence of proper acid placement is probably still the biggest reason why add jobs fail (besides improper well diagnosis). A well-conceived, properly designed treatment in all other aspects (formation damage assessment, selection of acid types, concentrations, volumes, and additives) can go for naught if the treatment is not properly placed. The zone of interest must be suffidently contacted by stimulation fluids. 

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