Comparative Study of Local Cements with Imported Class G Cement at Different Temperatures for Oil Well Cementing Operations in Ghana
The purpose of this research is to determine the suitability of local cements as an alternative to imported class G cement at different temperatures using oil well cement additives. Laboratory investigations on both local and imported cements to determine physical properties such as thickening time, fluid loss, compressive strength, free fluid and rheology were conducted at bottom hole circulating temperature of 27°C (80°F) and 66°C (150°F). The results indicated that locally manufactured cements are compatible with oil well cement additives at 80°F and 150°F and can be used as an alternative to imported class G cement in oil and gas well cementing operations. However, premature gelations of test results were phenomenal at 66°C (150°F) for the entire locally manufactured cements especially sample CEM B. Therefore, for local cements to be used effectively for cementing high temperature operations, stringent quality control during their manufacturing process is imperative.
Experimental Evaluation of the Performance of Fresh Nano Zeolite as an Oil Well Cement Additive
Cementing oil and gas wells require materials that, not only meet performance standards but also fairly different from those encountered in conventional processes. The search for alternative materials for cementing oil wells has increased worldwide. It is desirable that these alternative materials make cement sheath stronger, durable, flexible, cost-effective and more resistant to shocks. This research aimed at evaluating the performance of fresh nano zeolite as an additive for shallow oil well cementing operations. Laboratory tests were conducted on a base cement slurry mixed with different concentrations of fresh nano zeolite from 1% bwoc to 3% bwoc at a Bottomhole Circulating Temperature (BHCT) of 80°F (27°C) to determine physical properties such as compressive strength, thickening time, rheology, free fluid, and fluid loss. The results showed that the compressive strength of the cement slurries improved significantly at 12 hours than 24 hours curing period at 87°F (31°C). As the concentration of fresh nano zeolite increases less time was required to reach 50 psi, 100 psi and most importantly 500 psi which is needed to resume drilling operations. An increase in concentration of fresh nano zeolite at 80°F (27°C) resulted in an increase in the thickening time of all the cement slurries. This shows that fresh nano zeolite has a high retardation effect. Generally, the addition of fresh nano zeolite from 1% bwoc to 3% bwoc improved the carrying capacity of all the cement slurries. Test results also showed that increasing the fresh nano zeolite concentrations resulted in a decrease in rheological values which is a characteristic of a dispersant. Plastic viscosity values were observed to have an increasing trend generally with an increasing concentration of fresh nano zeolites. All the cement slurries were below 100 cP and therefore pumpable. The addition of fresh nano zeolite to the base cement slurry increased the free fluid of the cement slurries. The fresh nano zeolite didn’t have any effect on fluid loss and therefore does not exhibit characteristics of a fluid loss agent.
Points of strong summability of Fourier series
In this paper we present a new solution of Hardy and Littlewood's problem concerning strong summability of Fourier series; we also present a property of points of strong summability.