(56a) Effect of Date Pit Based Additive on the Thermal Stability of Water-Based Drilling Fluid: Experimental Studies and Mathematical Modeling

Successful completion of oil and gas wells depends to a large extent on the properties of the drilling fluid used during the operation. The ability of drilling fluids to perform their fundamental functions is measured by certain performance properties including fluid loss prevention, stability under various temperature and pressure operating conditions, and stability against corrosion. Varieties of additives (such as polymers) are usually added to drilling fluid formulation in order to fulfill these property requirements. However, the poor thermal stability of such additives makes it difficult for them to be used in high temperature and high pressure drilling operations. Naturally occurring composites (such as date pit) are a new set of materials that are currently generating interest in varieties of applications. Date pit is a green, readily available and cheap material with superior thermal stability as compared to the polymers. Therefore, the objective of this work is to investigate the effect of date pit particles on the thermal stability of water â?? based drilling fluid formulation.

Infusion method was used to prepare date pit particles/poly (2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMS) composite. Commercial Bentonite (Alumino Silicate Hydrate Montmorillonite) was used as the base material for preparing the water based drilling formulation. The formulation was prepared by adding 22.5g of Bentonite and the composite additive in 400ml of pure water. The percentage weight of the composite additive that was used ranges from 0.5 to 10 wt percent. Thermal stability of the formulations with and without date pit particles was evaluated using thermogravimetric analysis within a temperature range of 30 and 600^oC under N₂ environment. Particle size analysis was done using laser light diffraction. FTIR study was also performed to evaluate the interaction between the additives and the bentonite.

In our previous studies, it was observed that the addition of 10wt% composite increased the rheological properties (PV, YP and YVR) by 80, 33 and 35% respectively, decreased the filter cake thickness by 35% and reduced the amount of fluid loss by 44%. The results from the present study revealed that the thermal degradation temperature of pure bentonite, date pit and PAMPS are 455, 250 and 160^oC, respectively. Formulations with 10wt% date pit additive can be used up to a temperature of 300^oC with only a 8% drop in the thermal stability while the thermal stability of the formulation with only PAMPS (without date pit) additive decreased by 53% at the same temperature as compared to the formulation without additive. Therefore, the prepared composite demonstrated some potential for use as a drilling fluid additive in high temperature environment. This observation is an eye opener into the suitability of date pit based drilling fluid formulation for high temperature and high pressure drilling fluid operations. The research outcome is expected to provide useful information regarding the use of readily available cheap waste materials for oil and gas exploration.