Wednesday, March 5, 2014 | 11:20
a.m.-1:00 p.m. | Banquet Room, 30th floor, Summit Club
Speaker: Michael Redman, Halliburton
Topic: “Effects of Ambient Temperature Change on Diagnostic Fracture Injection Testing"
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Diagnostic Fracture Injection Tests or (DFITs) are used as an important tool for estimation of key reservoir and fracture parameters in unconventional oil and gas wells. A DFIT consists of pumping a small volume of fluid (10-20bbl) into the formation to break it down before closing the wellhead in and recording the pressure decline. The pressure decline is captured with a high accuracy dual quartz digital pressure recorder at the wellhead or downhole and is subsequently analyzed for reservoir and fracture parameters.
As the use of DFITs has increased across the industry, it has been found that some DFITs are unanalyzable due to pressure cycling during the falloff. The 24 hour periodic behavior of this cycling indicates that ambient temperature change is affecting the falloff data captured by the pressure gauge. The inherent physical properties of quartz enable a dual quartz gauge to capture extremely accurate pressure data but also make it quite reactive to temperature change. Without proper thermal compensation, this will result in inaccurate data unsuitable for analysis. Because they operate in an isothermal environment, it is believed that bottom hole pressure recorders will not suffer the same inaccuracies.
This paper will show that the effects of ambient temperature change on dual quartz pressure recorders can be broken down into two areas of concern that are common to both surface and bottomhole recorders. It will be shown with comparison plots of simultaneous surface and bottomhole pressure data that dual quartz crystal pressure recorders can be effectively compensated for the effects of ambient temperature change on the quartz crystal itself. Additionally, it will be shown that ambient temperature change at the surface can cause the fluid inside the wellhead to expand and contract. It will be shown that this is the primary cause of the pressure cycling that makes DFITs unanalyzable and that these pressure cycles are seen in both surface and bottom hole pressure recorders. A field example is presented that demonstrates a new method to reduce the effects of ambient temperature change during a DFIT. This results in improved data quality and analysis.
Michael Redman is the Senior Technical Manager for the SPIDR group in Halliburton’s Testing and Subsea Product Service Line. Prior to its acquisition by Halliburton in 2012, Michael was the chief engineer for Data Retrieval Corporation, developers of the SPIDR well testing system. While he has been involved in virtually every aspect of the SPIDR business over the course of his career, his primary focus has been on data acquisition, the design and analysis pressure transient tests, and modeling surface pressure data to bottomhole conditions. He has been involved on thousands well tests around the world for independent, major and national oil companies. Mr. Redman has over 15 years of experience in the oil and gas industry, is a graduate of the University of Houston with a BS in Chemical Engineering and is a member of the Society of Petroleum Engineers (SPE).