This conveyance system incorporates a drop-float valve in the BHA to allow tools to pass through it for drop off or pick up, which also helps maintain well control at all times during the operation. As many shale gas wells require up to 20 stages, this failure rate can translate to an operator overspending on a single well by several million dollars. Typically, the largest cost of completing an unconventional well is the fracturing stage, with each stage costing up to US $250,000. This often proves to be a costly decision because the act of blindly fracturing an entire interval can result in a high number of perforation clusters contributing to a small percentage of total production. In long-lateral shale oil and gas wells, rather than convey logging tools to identify those zones that are most conducive to hydraulic fracturing, operators may decide to fracture the entire section. The industry's common approach has been to simply avoid logging in laterals altogether. Hence this conveyance technique presents additional risks in the form of incomplete datasets, increased capital costs, and safety concerns for the rig crew, who are simultaneously tripping pipe and running wire downhole. Getting the tool past a sticky section of the well bore requires rotating the pipe, which is not possible using conventional wireline logging. This is particularly relevant in shale wells, which are inherently sticky by nature. The second limitation is the cable itself, which does not provide freedom to the driller. This is largely a result of two limitations: first, because conventional wireline logging involves pushing the tool downhole, any ledge or other obstruction encountered runs the risk of hindering forward motion or damaging the tool. In laterals, conventional wireline logging becomes more difficult, more prone to failure, and more risky. Traditionally, the conveyance technique of choice has been wireline, which delivers formation evaluation logging tools to total depth (TD) such that accurate completion decisions can be made for the optimal long-term viability of the well.
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