Abstract

Applied research has been undertaken to examine the potential of kaolinite combined with a kaolinite fixation agent to;

  1. Increase squeeze lifetime through alteration of near wellbore surface characteristics and mineralogy and,

  2. Provide water shut off control.

With respect to enhancing squeeze lifetime, it is documented that kaolinite increases the quantity of inhibitor adsorbed. Conversely, clean sandstone with low clay content commonly provides a poor substrate for adsorption. Furthermore, in reservoirs that experience near wellbore formation damage due to kaolinite mobilisation, it has been shown that use of a fixation agent as part of a squeeze treatment can increase squeeze lifetime. Using these facts, research has assessed the feasibility of injecting microcrystalline kaolinite (average particle size 2 µm) combined with the fixation agent and scale inhibitor as a means of mechanically altering near wellbore mineralogy and surface property characteristics within clean, high permeability sandstones. The testing has been designed to mimic the squeeze procedure used in the field for performing such a job and involves no additional steps to that used in a normal squeeze, i.e. Pre-Flush ? Main Treatment ? Over-Flush. The paper presents the results of coreflood experiments that have been undertaken to demonstrate "proof of concept" for the above along with examples of potential field applications.

A further concept, born from the initial idea, was the use of kaolinite and fixation agent for efficient, low cost, environmentally friendly water shutoff. There are several available products for water shutoff but the disadvantage of these is that they are not acceptable for use in Norway due to poor environmental characteristics. Hence, there was a need to fill this gap by developing water shutoff technology to meet country specific environmental legislation. The paper provides details of coreflood testing, where an excess of kaolinite has been used to form an internal and external filter cake that is attached to the wellbore face and within the near wellbore using the fixation agent.

The paper draws on data from StatoilHydro operated fields in order to highlight the potential of this innovative approach to downhole scale management and water control.

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