Laboratory Study of Oil Palm Kernel Shells and Mangrove Plant Fiber Banana Trunk Fiber as Lost Circulation Materials in Synthetic Based Drilling Mud
Authors: Isaac Prince Ekeoma , Dosunmu Adewale , Anyanwu Chimaroke 
Published: July 2019

Lost circulation will be a heavy drawback throughout the drilling of an oil well or gas well. Existing mitigation depend for the most part on particulates, which regularly are added to drilling fluids to plug fractures and to develop mud cake to fix drilling fluid losses.

Evaluation and testing of LCM in the laboratory before field applications are crucial, Laboratory study was undertaken to compare the performance of conventional lost circulation materials (Mica and Calcium Carbonate) with Palm Kernel Shells and Banana Trunk Fiber as a new blend of lost circulation materials in varying proportions using synthetic based drilling mud. Palm kernel Shells and Banana Trunk Fiber were prepared and sieved to obtain coarse, medium and fine particles which were analyzed in the laboratory to determine Mud density, Particle Size Distribution, Rheological Properties, Permeability plugging efficiency and Acid Solubility using Mud balance, Sieve Analysis, 45-Fann Viscometer, Permeability Plugging Apparatus (PPA) and Acidic Reagents (Hydrochloric and Formic Acid) respectively.

The tests were performed to simulate downhole conditions, it was seen that a 2:1 blend of Palm Kernel Shell-Coarse and Banana Trunk Fiber-Medium passes API acceptability test for API acceptable range of plastic viscosity and yield point, but the fine size grades performed poorly. Also, the 2:1 blend of Palm Kernel Shell-Coarse and Banana Trunk Fiber-Medium outperformed the 2:1 blend of Calcium Carbonate-Coarse and Mica-Medium in the synthetic based drilling mud tested. The plugging capacity of the blended mixture of the LCM were tested using a permeability plugging apparatus, the result shows that the sealing efficiency is highly dependent on the fracture width and particle size distribution. Palm Kernel Shells alone were not able to plug the tapered slot and hence the Plug Breaking Pressure (PBP) was zero. The test was carried out at an operating pressure of 3000psi and 200?. It was also observed that the total fluid loss of the 2:1 blended mixture of Palm Kernel Shells and Banana Trunk Fiber is low when compared to same blend of Calcium carbonate and Mica which implies that the former has high ability to form semi permeable filter cake that will seal off depleted intervals and help prevent differential sticking than the latter. Acid Solubility in a reservoir or production zone is important, LCM used in these zones must be removed to permit maximum formation production, when tested with hydrochloric and formic acids, Palm Kernel Shells and Banana Trunk Fiber are both degradable in both 10% of Hydrochloric and 10% Formic acid. Hence, the blended mixture of Palm Kernel Shells and Banana Trunk Fiber is a suitable substitute for conventional LCM.

This work confirms that all LCM are not equal, and that the LCM type plays a role in terms of both plugging and "toughness" that better withstands displacement pressures. It also validates that LCM combinations function more efficiently than using just one type alone. The Novel Rheology and PBP data can be used as a reference when designing other LCM to be used in future studies.