Abstract: A fluid for use in hydraulic fracturing contains underivatized guar or a guar gum derivative as viscosifying or gelling polymer, a crosslinking agent, carbon dioxide as foaming agent and urea and, optionally, a bifunctional organic compound containing at least one hydroxyl group and at least one quaternary group and, optionally, a non-gaseous foaming agent. The fluid may be characterized by a low pH such as a pH than or equal to 3.0 and less than or equal to 5.0.

Abstract: A fluid for use in hydraulic fracturing contains underivatized guar or a guar gum derivative as viscosifying or gelling polymer, a crosslinking agent, carbon dioxide as foaming agent and urea and, optionally, a bifunctional organic compound containing at least one hydroxyl group and at least one quaternary group and, optionally, a non-gaseous foaming agent. The fluid may be characterized by a low pH such as a pH than or equal to 3.0 and less than or equal to 5.0.

Abstract: Systems and techniques of monitoring, assessing and determining the quality of software components and/or their associated features that may be designed and built to be run on a plurality of hardware devices. Such hardware devices may be devices made by different manufacturers. In addition, certain of these manufacturers may be device partners with the software maker. Software product and/or components may be subjected to test runs on various hardware devices and the results may be correlated. This pass/fail data may also be correlated against a number of additional factors—e.g., the market share of device products for which a software product has a minimum level of acceptable or passing rates.