Testing and modeling of filter cake formation using new seepage-consolidation concept

Abstract

The behavior of filter cake formation has been investigated using new seepage-consolidation concept. This study is focused on the precious measurement of the fluid loss that affects several applications such as the interaction between the concrete and the pipe in the oil well application and bored piles, pipe stuck problems, and oil well production. Currently, American Petroleum Institute (API) model is being used to model the filter cake formation. The API-model has assumed several unrealistic assumptions such as infinity fluid loss at infinity time period, constant filter cake permeability during filter cake formation, constant relative solid content in the filter cake to the mud, and constant cake porosity during cake formation. Hence, the combination of seepage and consolidation phenomenon has been used to preciously model the filter cake formation. In addition, a new consolidation equation was derived based on the fact that the cake permeability is time dependent function. In the proposed solution, a coupling function of time and elevation was used to express the excess pore pressure function. The proposed solution was verified against Terzaghi consolidation solution and API model for long-term experimental results for both 2% and 8% bentonite drilling mud under a constant pressure of 690 kPa and different temperatures of 25°, 50°, 75°, and 100 °C. The verification included the variations of the fluid loss, permeability, coefficient of consolidation, and excess pore water pressure with the time. It was concluded that the new method has better prediction for the experimental results than both Terzaghi consolidation solution and API-model. The pore water pressure for 2% bentonite drilling mud at 25 °C decreased by 24% and 26% over 420 min using Terzaghi and new proposed method respectively. Keywords: Filter cake formation, Seepage, Consolidation, API-model, Bentonite drilling mud, Coefficient of consolidation, Excess pore pressure