Gel Strength lbs/100 ft2 (10 sec/10min)
This is a measurement that denotes the thixotropic properties of the mud and is a measurement of the attractive forces of the mud while at rest or under static conditions. As this and yield point are both measures of flocculation, they will tend to increase and decrease together, however a low yield point does not necessarily mean 0/0 gels!
Gel strength is measured with the viscometer by stirring the mud at high speeds for about 15 seconds and then turning the viscometer off or putting it into neutral (low gear if it's a lab model) and waiting the desired period, (i.e., 10 seconds or 10 minutes). If the viscometer is a simple field model, the “gel strength” knob is turned counter clockwise slowly and steadily. The maximum dial deflection before the gel breaks is then recorded in lb/ 100 ft2. With a lab model, the procedure is the same except a low speed is used. After a wait, the second gel can be taken in a similar manner. Gels are described as progressive/strong or fragile/weak. For a drilling fluid, the fragile gel is more desirable. In this case, the gel is initially quite high but builds up with time only slightly. This type of gel is usually easily broken and would require a lower pump pressure to break circulation.
