Guidelines to Successful Dewatering of CBM Wells

Abstract

Introduction Pumping water from a well is a straight forward effort that has been done for centuries. Pumping fluid from relatively shallow wells should be an easy task. Normally a pump is installed in a well, started and then forgotten. This premise does not hold true in CBM wells. In CBM wells, this pumping process can be complicated by many issues unless precautions are taken. This paper is designed to address the basic precautions that can be taken to improve de-watering of CBM wells. These precautionary steps can save the operator money by reducing the month to month maintenance associated with CBM wells. Although we cannot cover every potential pitfall to de-watering operation, the basic steps discussed will identify potential problems and offer ideas to address them. Well Planning for Artificial Lift The successful de-watering of CBM wells, especially Coal Bed Methane (CBM) wells takes some planning before the first well is dilled. Many factors should be taken into consideration so that the operation can be economical for the entire life of the well. Unconventional gas has gone from an experiment to a logical and viable energy source. Pre-planning can and will reduce the overall cost of operation over the life of a CBM well. Short cutting the pre-planning stage can often take perceived savings in well drilling costs and transfer these costs to much higher day to day maintenance costs and lower gas production, thus decreasing the economics of the play. The learning curve has been steep for operators and suppliers as well as we all try to find solutions to the many challenges that face the industry. The first step is to identify the type of coals to be de-watered by asking these questions. Are the cleats in the coals easily fractured? How thick are the coals? Do the coals contain sand, clay or other solids that could interfere with pump operations? Are their multiple coal zones and what kind of material separates the zones? Are their other CBM wells producing from the same formations and what problems have they encountered? Pre-planning will reap benefits in lower operating costs and maintenance and higher profitability for the operator.