Rice husk and saw dust as filter loss control agents for water-based muds

Efficient removal of lead and arsenic using macromolecule-carbonized rice husks

The adsorption process using inexpensive adsorbents is one of the methods to remove contaminants from aqueous solutions. Biomass porous carbon based materials are among the most widely used adsorbents in this field. Rice husk is a bio-based adsorbent material for pollutant removal. In this study, the porous carbon material obtained from the rice husk was used for the adsorptive removal of lead (Pb) and arsenic (As) from aqueous solutions. Silica was removed from rice husk structure through the one-step reaction using PTFE. The morphological and crystallographic characteristics of the adsorbent surface were determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The removal efficiency was investigated under different conditions of pH (3–9), contact time (3–90min), adsorbent amount (0.5–6 g/l) and initially adsorbed concentration (10–100 μg/l) by changing the parameters in the adsorption reactions. The Response Surface Method (RSM), a Box-Behnken design (BBD), was used to optimize adsorption of Lead and Arsenic by Rice husk. The removal efficiency was finally calculated using analysis of variance. According to the adsorption analysis results, the removal efficiency of Pb and As in aqueous solutions increased (up to 97%, 85% for Lead and Arsenic) under optimum conditions.

Evaluating the locally sourced materials as fluid loss control additives in water-based drilling fluid

In the exploration for hydrocarbons, a successful drilling operation to the desired depth hinges on the effective performance of the formulated drilling fluid. Apart from carrying drill cuttings to the surface, another major function of the fluid is to seal off the walls of the wellbore to prevent fluids from coming into and out of the wellbore while drilling a well. Numerous commercial fluid loss additives: carboxymethyl cellulose (CMC), polyanionic cellulose (PAC), among others have been in existence with their drawbacks and effect on the total drilling cost. This study evaluates the use of locally sourced materials: Detarium microcarpum, Brachystegia eurycoma and rice husk, as fluid loss control additive in the water-based drilling fluid. The materials were prepared, ground and sieved to 125 microns. Four sets of water-based drilling muds were formulated using the local materials and CMC as fluid loss control additives. The mud formulation was based on the American Petroleum Institute (API) standard of 25g bentonite to 350mL of water. Also, the filtration test of the formulated muds was performed using API recommended practice for static filtration test at low temperature - low pressure (LTLP) condition. The results obtained showed that Detarium microcarpum and rice husk fluid loss volume and filter cake thickness were comparable with that of CMC from additive content of 10g, while Brachystegia eurycoma was comparable from additive content of 15g. Furthermore, the composite additive results indicated that Detarium microcarpum-rice husk at 95% Detarium microcarpum-5% rice husk performed better than Brachystegia eurycoma-rice husk of the same combination. Additionally, the fluid loss volume and filter cake thickness of Detarium microcarpum-rice husk additive were comparable with CMC from 10g content. Also, the results revealed that the fluid loss volume and filter cake thickness obtained from the locally sourced materials were within API specification for fluid loss control agents. The mud filter cake characteristics exhibited by these materials depicted that they have slippery, smooth and soft mud cakes; thus, the characteristics of a good mud cake that will prevent differential pipe sticking.