Suspension Composition for Cement Slurries

Example 1

A formulation of a suspension composition of the type in the present disclosure for 1000 gram fluid is listed in Table 1 below. The suspension composition was prepared and used in Examples 1 and 2.

The suspension composition was firstly used in stability tests. The suspension composition was kept static in a standing 25 ml measuring cylinder to observe mixture stability.

After 21 days from preparation, density of the suspension composition was checked from top, middle and bottom portion of the suspension composition and shown in Table 2.

As shown in FIG. 9, after 28 days from preparation, there was no visible separation of the suspension composition and the suspension composition was pourable. The results show that suspension composition was stable and uniformly dispersed throughout the suspension composition.

Physical properties were measured for the suspension composition and shown in Table 3 below.

Example 2

Wellbore servicing fluids were prepared using a dry powder suspending agent or the suspension composition in Example 1. Test conditions and formulas of the wellbore servicing fluids are listed in Tables 4 and 5. The amounts of the cement blend composition are based on the total weight of the cement blend. The amount of the dry powder suspending agent is based on the total weight of the cement blend, while the dry powder suspending agent is not a part of the cement blend. Both of the wellbore servicing fluids had a density of 14.60 lbm/gal and a specific gravity of 1.75. The amount of the dry powder suspending agent in wellbore servicing fluid 1 (WSF1) was 1.3 g per 600 ml WSF1, which was equivalent to the amount of the crosslinked guar gum in wellbore servicing fluid 2 (WSF2).

Table 6 below shows 24 hr sonic compressive strength is lower in WSF2 compared to WSF1, however other properties are comparable.

Table 7 shows that the rheology data measured by a Fann® Model 35 viscometer for WSF 1 and WSF 2 are comparable.

Further, WSF1 and WSF2 were cured at 168° F./5.000 psig for 7 days and then tested for mechanical properties. The results are in Table 8 below.

The experiments demonstrate the following. 7 days curing data shows there was no adverse effect of the use of the suspension composition on mechanical properties of set cement. UCA Compressive Strength shows a slight delay in strength development for WSF2. Regarding to other slurry properties such as mixability, free fluid, rheology, gel strength, and fluid loss, there was no adverse effect of the use of the suspension composition by comparing WSF1 and WSF2.