Many factors differentiate deep-water cementing operations from shallow-water cementing operations. Some of these factors are:
• Narrow window between frac and pore pressures – in many complicated cementing jobs, as the cement column begins to enter the annular space, the equivalent circulating density (ECD) approaches or exceeds the frac gradient. In these cases, low-density fluids are commonly used to prevent induced losses.
• Naturally fractured formations – technology is crucial to achieve a successful cementing job in lost circulation zones.
• Temperature – due to the high extension of water depth, low temperature gradients affect the behavior and properties of the fluids.
• Hydrostatic pressures – proportional to the water depth, the hydrostatic pressure exerted over the fluids in the well increases.
Lost circulation is a major problem often encountered while drilling and cementing wells. Lost circulation events can generate mud loss, hole instability, and an increase in rig time. All of these circumstances increase non-productive time (NPT) and overall rig costs.