Development of framework for predicting water production from oil and gas wells in Wattenberg Field, Colorado.

摘要

Water issues in the oil and gas industry have drawn attention from various stakeholders including the public, industry and environmental groups. With the increasing demand for energy, the number of oil and gas wells has increased greatly providing 60% of the energy in the United States. Besides the large volume of fresh water required for drilling and hydraulic fracturing, wastewater from the well can also lead to serious problems. The current approach for managing wastewater from oil and gas fields is deep well injection or evaporation both of which can potentially cause environmental issues. One of the best strategies to solve water issues from oil and gas operations is to reuse wastewater as drilling and fracturing water so the volume of fresh water required and wastewater disposed can be reduced. Information on both water quantity and quality are required when designing wastewater reuse treatment facilities. This study provides a framework for understanding water production trends from oil and gas wells in the Wattenberg field in Northern Colorado by analyzing historical data from Noble Energy Inc. The Arps equations were chosen for modeling water production from oil and gas wells. After studying 1,677 vertical and 32 horizontal wells in Wattenberg field, an exponential decline function was applied to model the produced water production of all the wells and the frac flowback water of horizontal wells. An Excel based 30-year water production prediction tool was developed based on the two protocols developed for vertical and horizontal wells in the Wattenberg field. Three case studies of different subsets of oil and gas wells were examined to illustrate the function of the tool. In addition, a comparison of exponential and harmonic functions was made in the third case study, and a significant difference was observed. The harmonic decline function predicts a less aggressive decline resulting in higher production volumes. It was concluded that in the absence of long term production data, the harmonic decline function should be used since the exponential decline function may underestimate the volume of produced water.