Using Continuous Real-Time Compositional Gas Data for Horizontal Drilling and Detection of Natural Gas Liquids (NGL)

Nagel, William

The oil and gas industry has seen a rapid increase in horizontal drilling and the corresponding need for reliable formation data to make steering decisions. Additionally, finding Natural Gas Liquids (NGLs) and properly completing a well have become more critical to making a well economical. These processes become easier when compositional gas data is available.

Knowing whether a well bore is a zone containing Natural Gas Liquids or Dry Gas is very important to type of hydrocarbons that will be produced. Horizontal wells can be kept in the Liquids zone by steering the well bore vertically.

The use of Gas Chromatographs do not provide a continuous real-time compositional real-time gas trace. Gas Chromatographs have a very low data frequency associated with long cycle times. Low data frequency means that there is only compositional data for every 10-20 feet. In addition Gas chromatographs require technical staff onsite.

A revolutionary new technology utilizing tunable filter spectroscopy allows the collection of real-time, accurate compositional gas data without additional technicians on location. This technology enables the development of instruments that deliver the best of both worlds; real time compositional gas data in a rugged unmanned solution. This eliminates the need for complicated, expensive and temperamental gas chromatographs.

Through the use of tunable filter spectroscopy compositional data is collected. The gas readings are broken down into individual concentrations of methane, ethane, propane, n-butane, i-butane, n-pentane, i-pentane, and CO2. This data is available at 1 second intervals, a remarkably higher frequency than gas chromatographs are able to provide.

The compositional data collected with this technology forms the basis for plots of the wetness, balance, and character ratios. These ratios are critical geological indicators used to define the oil/gas and oil/water contact points and detect the presence of natural gas liquids in the formation. Additionally this data can be used to infer geological properties of the formation being drilled and thus make better steering, drilling, and completion decisions.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013