SummaryToxoplasma gondii is an obligate intracellular protozoan pathogen. We previously found that genes mediating cellular responses to hypoxia were upregulated in Toxoplasma -infected cells but not in cells infected with another intracellular pathogen, Trypanosoma cruzi . The inducible expression of these genes is controlled by the hypoxia-inducible factor 1 (HIF1) transcription factor, which is the master regulator of cells exposed to low oxygen. Because this response may be important for parasites to grow at physiological oxygen levels, we tested the hypothesis that HIF1 is important for Toxoplasma growth. Here, we demonstrate that Toxoplasma infection rapidly increased the abundance of the HIF1 α α α α subunit and activated HIF1 reporter gene expression. In addition, we found that Toxoplasma growth and survival was severely reduced in HIF1 α α α α knockout cells at 3% oxygen. While HIF1 α α α α was not required for parasite invasion, we determined that HIF1 was required for parasite cell division and organelle maintenance at 3% oxygen. These data indicate that Toxoplasma activates HIF1 and requires HIF1 for growth and survival at physiologically relevant oxygen levels.

Summary The Granite Wash unconventional gas and oil play of the US midcontinent has a multitrillion-cubic-feet-equivalent upside potential. The condensates and natural-gas liquids associated with this gas play make it one of the most-prolific and fastest-growing unconventional fields in North America. However, efficient extraction of hydrocarbons from the Granite Wash play poses drilling and geological challenges. The Granite Wash deposit has significant lateral variation, with extremely abrasive thinly bedded sandstones. Geological complexity of this field requires precise placement and navigation of the wellbore in real time to overcome the variable characteristics of the reservoir. To overcome these challenges, logging-while-drilling (LWD) technology was used in conjunction with geosteering. An azimuthal gamma ray image was used to determine formation bed dip and stratigraphic complexity within the reservoir. Multiple-propagation resistivity measurements were used to correlate position within the reservoir and indicate formation porosity. The LWD data was transmitted in real time by means of satellite to a remote reservoir-navigation center where the reservoir-navigation engineer incorporated the real-time data into the geological model. This strategy has been implemented to drill with excellent results, as compared with the offset wells. The initial production rate obtained was 19.4 MMcfe/D (cfe = cubic foot equivalent). The well was completed 10 days ahead of schedule, resulting in significant cost savings. With the successful implementation of real-time reservoir-navigation and drilling technology, the operator accelerated their drilling program. The results are significant organic production growth, improved drilling performance, precise placement of the wellbore, and significant reduction in rotating hours at lower drilling and production costs.

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The Granite Wash unconventional gas and oil play of US Midcontinent has a multi-trillion cubic feet equivalent upside potential. The condensates and natural gas liquids associated with this gas play make it one of the most prolific and fastest growing unconventional fields in North America. However, efficient extraction of hydrocarbons from the Granite Wash play poses drilling and geological challenges. The Granite Wash deposit has significant lateral variation; in some locations the thickness of the sandstones bodies associated with gas shows are approx 1 to 3 feet thick, and the formations are extremely abrasive. Geological complexity of this field requires precise placement and navigation of the wellbore in real-time to overcome the variable characteristics of the reservoir. To overcome these challenges, logging while drilling (LWD) technology was used in conjunction with geo-steering. The azimuthal gamma ray image was used to determine formation bed dip and stratigraphic complexity within the reservoir. The multiple propagation resistivity measurements were used to correlate position within the reservoir and indicate formation porosity. The LWD data was transmitted in real-time via satellite to a remote reservoir navigation center where the reservoir navigation engineer incorporated the real-time data into the geological model. This strategy has been implemented to drill with excellent results as compared to the offset wells. The initial production rate obtained was 19.4 MMcfe/d. The well was completed 10 days ahead of schedule, resulting in significant cost savings. With the successful implementation of advanced real-time reservoir navigation and drilling technology, the operator has accelerated the drilling program. The results are significant organic production growth, improved drilling performance, precise placement of the wellbore and, significant reduction in rotating hours at lower drilling and production costs.