By observing the relationship between Reynolds number and the critical velocity of a fluid, it is noticed that they respond inversely as the flow properties of a fluid are changed. As the fluid properties increase and the fluid becomes more viscous, the critical velocity increases and the Reynolds number decreases which causes the fluid to flow in a more laminar state. Keeping the fluid flow in a laminar condition, tends to aid hole cleaning and can minimize shale associated problems. Therefore, by altering the pertinent variables, we can control the Reynolds number of a fluid.

Finding the maximum Reynolds number to use as a guideline in a certain area requires a comparison to be done. This comparison should be conducted on wells where shale problems occurred and on wells where no problems where encountered. By plotting the Reynolds number and the critical velocity of the drilling fluid verses depth, crossover points should occur on the wells which experienced shale problems. Once these points are identified, a minimum Reynolds number value can be obtained and used as a guideline for the area.

For this paper, the flow patterns on twenty wells in the Texas Panhandle area were analyzed. A Reynolds number range of 3100 to 4000 was identified and wells which experienced severe crossover had a greater occurrence of shale problems. Using this technique, as a guideline, has greatly reduced our shale related problems.

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