Effect Of High Temperature And High Pressure On Filtration Of Water–Based Muds

The objective of this thesis was to study the effect of high pressure and high temperature on filtration of water-based mud with an aim to improve filtration in HTHP conditions.In order to achieve to the above objectives,systematic study on drilling fluid components was conducted by formulating appropriate fluid systems.The outcome was used as a guideline in formulations consisting of a combination of components and finally appropriate fluid systems were formulated for thorough study.The investigation involved filtration experiments on a number of drilling fluid systems,and other tests such as viscosity,density.Filtration experiments were conducted at temperatures of25 ^oC,100 ^oC,150 ^oC and as well pressures of 0.5 MPa,1 MPa,2 MPa,3 MPa,3.5 MPa,Permeability and porosity was evaluated pertaining to different kinds of filter cakes.Filtration experiments were conducted for 30 minute intervals and filter cake thickness,cumulative filtrate volume against time and ratio of wet to dry cake mass were measured as well.In most cases the influence of pressure was negligible with slight increments in filtration but adversely affected by the temperature with most mud samples indicating increased filtration rates with increasing temperature.On a few occasions such as that of salt water-based systems higher pressures yield a reduction in filtration.It was found that at a pressure of 2 Mpa appeared to be optimum as it resulted in lower filtration for salt-based system.Permeability of the filter cakes of most muds was greatly affected by pressure yet temperature had little influence.Based on the available information a general filtration equation was adapted,with modifications that were in line with the experiments.The aim was to attempt to predict filtration at high temperatures and high pressures.In order to achieve this,the equation was used to fit the available information unto experimental data.The results were to some extent in agreement.This enabled the evaluation of average specific static cake resistance effective filter medium resistance,permeability,porosity of the cake.Given the availability of the above information an attempt was made to predict static filtration with meager success.Permeability of cakes were in the range of（2.084 to 0.3785）x10^-10D.