Enhanced Coal Bed Methane Recovery Using Ni-trogenase Enzyme

Abstract

Energy consumption is increasing by 5.6% per annum, so it is today’s requirement to extract more efficiently from currently available reservoirs and to find novel energy resources. coalbed methane (CBM) is one such unconventional hydrocarbon resource, which is easily extractable. This paper focuses on enhanced CBM recovery using biogenic enzymes for increasing secondary recovery. The primary recovery of CBM is nearly 50% and the conventional secondary recovery using gas injection technique is around additional 6 to 8%. Here, use of thermostable nitrogenase enzyme is suggested to fix the injected nitrogen. The enzyme can be generated in biochemical plants. The nitrogenase enzyme is immobilized for longer and sustained activity. The immobilized enzyme suspended in the proper medium is then injected into the well bore. This enzyme instantaneously converts injected N2 into NH3. A complete study starting from isolation and immobilization of the enzyme to competitive adsorption and dissolution of ammonia was done to derive at final results. This paper provides systematic approach and relevant theoretical explanation for the proposed technique, which is suggested for the first time. After considering the loss and dissolution of a minor amount of ammonia in water present in the coal seam, the improvement estimated is 12–14%.

The figures below illustrate the set up to implement the proposed technique.

 

Neeti Joshi graduated with a BS degree in petroleum engineering from Maharashtra Institute of Technology, Pune, India. She is the winner of the regional (Adelaide, 2006) and international (ATCE, Anaheim, 2007) student paper contests at the undergraduate level. Joshi is an active member of SPE and currently works for Shell Technology India as a reservoir engineer.

 

  1. Fig. 1—The basic setup of the project.
  2. Fig. 2—Distribution of ammonia in the adsorbed and dissolved phases in the coal cleat.