Comparative Evaluation of Rheological Properties of Standard Commercial Bentonite and a Locally Beneficiated Bentonitic Clay from a Marine Deposit in Upper Benue Basin, Nigeria

Abstract

Nigeria is ranked the seventh largest exporter of crude oil in the world. On a daily basis, it produces over two million barrels of crude Oil from hundreds of Oil wells drilled in the Niger Delta area. Not a single of these Oil wells are drilled without the use of Bentonite. Bentonite is a clay powder that is mixed with water (drilling mud) and forced through a drilling string into the wellbore during drilling operations in order to float and lift drilled cuttings out of the well, control the down-hole temperature, lubricate drilling bit, prevent corrosion and stabilize the wall of the hole from collapsing among other things. A very large sum of money is being spent by the Oil companies operating in Nigeria on the importation of millions of tons of Bentonite from overseas for Oil well drilling. Nigeria has large reserve of Bentonitic clay deposit that if properly utilized will go a long way in supporting the Oil well drilling demand in the country. This will translate into retaining the large sum of money sent overseas for importation of foreign Bentonite, create employment opportunities, bring external investment and boost the country’s economy. Though the Bentonite deposits studied are Ca-based, it can be beneficiated to a level that is comparable with the standard compliance. This study has beneficiated local Bentonitic clay using Na2CO3 as the beneficiating agent and ion exchange as the procedure. The rheological properties of the beneficiated clay were determined together with that of a standard commercial Bentonite and compared with the United State API grade and European OCMA standard for complience. The recorded values for viscosity at 600rpm, yield, filtration, fineness and moisture content of the locally beneficiated Bentonitic clay and the standard commercial Bentonite are 35, 1 -6, <15, 2.8%, 8% and 27, 2.3, <15, 3.7%, 12%, respectively. While these values for the United State API grade and the European OCMA standards are ≥30,≤3, ≤15, ≤4%, ≤13% and ≥30, ≤6, ≤16, ≤2.5%, ≤13%, respectively. This indicates that the local Bentonite reserve can be beneficiated using Na2CO3 as beneficiating agent and ion exchange as beneficiating procedure to a level that is even a little better than the studied standard commercial Bentonite also studied.