Gursat Altun

Dynamic Filtration Properties of Fresh Water Sepiolite-based Muds

The usage of sepiolite muds is not common in the drilling industry even though they exhibit better rheological properties under high temperature and high salinity environments than those of rivals due to their unacceptable high filtration losses. Recent studies have revealed that it is possible to obtain low filtrate rates from these muds along with commercial additives under static conditions at harsh temperatures and saline environments. On the other hand, the dynamic fluid loss behaviors of sepiolite muds are not a well known phenomena. There is no published work on the dynamic filtration behavior of these muds. The main goal of this study is to characterize the dynamic filtration behavior of sepiolite muds formulated with commercial additives under elevated temperatures and pressures. In addition, effects of particle size gradation of sepiolite clay on dynamic filtration properties of these muds are investigated. The variation of spurt loss volume, dynamic filtration rate, and cake deposition index properties of sepiolite muds are investigated with a computerized dynamic filtration apparatus. Numerous dynamic filtration loss histories with a test duration of 45 to 60 minutes at temperature conditions ranging from 200 to 400°F, a filtration pressure of 100 psi (0.7 MPa), and only one sample with 500 psi (3.45 MPa) have been conducted. Three key parameters, namely, spurt loss volume, dynamic filtration rate, and cake deposition index to characterize the dynamic fluid loss of sepiolite muds were determined experimentally. The experiments have resulted in acceptable dynamic filtration rate and cake deposition index values for the fresh water sepiolite-based mud at high temperatures. The experimental results promise that properly formulated sepiolite muds can be a good choice in geothermal well drilling beside their low cost advantages.

Extending thermal stability of calcium carbonate pills using sepiolite drilling fluid

Abstract The aim is to investigate the plugging ability of sepiolite clay water base drilling fluids over a wide range of high permeable zones at high temperature and high pressure conditions. The special emphasis of this study is to extend the usage of loss preventer material (LPM) as a component of fresh water sepiolite base mud that has never been investigated for this purpose before. The rheology and loss tests at 27−204 °C and 2070 or 6895 kPa revealed that the sepiolite drilling mud shows good rheology and high solid suspension capability at all temperatures except 149 °C, and low loss circulation at high temperature and high pressure. The Permeability Plugging Apparatus (PPA) experiment, in which the 10−90 µm permeable ceramic plate was simulated as formation, showed that the sepiolite drilling mud without CaCO 3 can not plug the pores, while the sepiolite drilling mud with CaCO 3 can plug the pores quickly and keep the CaCO 3 particles suspended even at high temperature (up to 193 °C). The PPA experiment results were proved by the analysis using SEM and ideal packing theory.