This study, “MODIFICATION OF NIGERIAN CLAY FOR APPLICATION IN DRILLING PROCESS” contains concise information that will serve as a framework or guide for your project work. The project study is well-researched for academic purposes and are usually provided in complete chapters with adequate References. Keywords: MODIFICATION OF NIGERIAN CLAY FOR APPLICATION IN DRILLING PROCESS
CHAPTER ONE INTRODUCTION
Petroleum drilling is the primordial step in the success of oilfield exploration. This success is based, on the one hand, on the important details derived from geological drilled formations and, on the other hand, on the good drill-in reservoir conditions. Thus, the paramount drilling objectives are to reach the target safely in the shortest possible time and at the lowest possible cost, with required additional sampling and evaluations constraints dictated by the particular application (Khodja, 2010). Drilling the wellbore is the first and the most expensive step in the oil and gas industry and it requires the use of drilling mud (fluid). The cost of drilling is reduced by about 15% when drilling mud is used and this is not small given the overall cost of drilling an oil or gas well (Dewu et al., 2011). It is a mixture of water or oil, clay, weighing materials, and few chemicals. The complex drilling fluids play several functions simultaneously. They intended to clean the well, hold the cuttings in suspension, prevent caving, and ensure the tightness of the well wall, flood diesel or water and from an impermeable cake near the wellbore area. The cleaning performance of bentonite is affected by many factors such as fluid viscosity, annular flow velocity, angle of inclination and drill cuttings size and shape (Al-Kayiem et al., 2010). Moreover, they also have to cool and lubricate the tool, transfer the hydraulic power and carry information about the nature of the formation by raising the cuttings from the bottom to the surface. The active solid is called bentonite. Bentonite is light-colored clay that expands in water. It is principally used for oil drilling mud formulation, fillers for paper, pharmaceutical products, adsorbents and catalyst in the chemical process industries. There three principal types of bentonite, namely: natural sodium bentonite or sodium montmorillonite, natural calcium bentonite or calcium montmorillonite, sodium activated bentonite or sodium activated montmorillonite. There are also the potassium, magnesium and lithium types. Bentonites are composed predominantly of clay minerals montmorillonites, a sub-group within the smectites group. It is clay derived from deposits of weathered volcanic ash. A general chemical formula for montmorillonites is m(Mg[Si4O10]x[OH]2)xp([Al,Fe]2x[Si4O10]), m:p = 0.8 – 0.9. Depending on the nature of their genesis a variety of accessory minerals occur along with the montmorillonites. These may include quartz, feldspar, calcite, gypsum, dolomite, biotite, crystobalite, plagioclase and ferruginous compounds. Impurities such as calcite, gypsum and crystoballite which affect the performance of Bentonitic clays can also be present (Oladipo et al, 2003). In oil and gas industry, Bentonite usefulness is based on its swelling and gel forming capacity when mixed with water and this swelling capacity is dependent on the relative Ca-Na content (Deverux,1999). Natural sodium bentonite as the name suggests, occurs with sodium as the predominant exchange cation. It is characterized by high swelling, high liquid limit and high thermal durability, and finds application as oil and gas drilling mud. Majority of bentonite occurring worldwide are of the calcium type. Calcium bentonite has lower swelling and liquid-limit values compared to natural sodium bentonite. The importance of bentonite as a mud in drilling operations in water, oil and gas well construction cannot be overemphasized. In these occurrences, it is found as a rock composed essentially of clay minerals formed as a result of devitrification and chemical alteration of some igneous material (Dewu et al, 2011).
Presently, there is no significant exploitation of Nigerian bentonitic clay for the purpose of drilling mud formulation despite its proven large deposits at different locations of the country. This is because it has lower swelling index and high fluid loss (Falode et al., 2007). Most of the bentonite used for drilling activities in Nigeria is imported into the country (Apogu-Nwosu et al., 2011). The importation of Bentonite for oil and gas well drilling operation has continued to divert some large amount of foreign exchange that would have impacted on the socioeconomic wellbeing of Nigeria. (Dewu et al., 2011). Also, attention has not been drawn towards modification of the clay before being used in drilling mud preparation. Improvement of the properties of these clays is imperative and timely. 1.3 Aim and Objectives The aim of this research work is to modify Nigerian clay by beneficiating with Sodium Hydrogen Carbonate (NaHCO3) for application in drilling process. The specific objectives are:
1.4 Scope of Study This research work will be limited to clay obtained at a mining site in Patigi, Kwara state. Beneficiation will be limited to the use of Sodium Hydrogen Carbonate (NaHCO3) as the beneficiating agent. Clay characterization will be limited to mineralogical composition, chemical composition, swelling index, pH and viscosity.
1.5 Significance of Study The use of bentonite in drilling operations in the oil and gas industry in the country is very significant. If efforts geared towards improving the suitability of Nigerian clay for use in drilling mud are successful, it will reduce the overdependence on imported bentonite by the oil companies and will go a long way in reducing the large sum of money spent on importation of foreign reserve thereby boosting the country’s economy and create employment opportunity.
Keywords: MODIFICATION OF NIGERIAN CLAY FOR APPLICATION IN DRILLING PROCESS
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