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Pinedale field is located in the northern part of the Green River Basin in western Wyoming about 90 mi (145 km) southeast of Jackson, Wyoming, near the town of Pinedale (Figure 1). It is one of the largest natural gas fields in the United States with ultimate recoverable reserves estimated to be about 39 trillion cubic feet (tcf) of methane-rich natural gas. Despite the huge gas reserves, the field's productive areal extent is relatively small as it is only about 30 mi (48 km) long and less than 5 mi (8 km) wide. The field covers an area of about 84 mi2 (220 km2). In this sense, it is a very concentrated gas resource.

Pinedale field is located in the northern part of the Green River Basin in western Wyoming about 90 mi (145 km) southeast of Jackson, Wyoming, near the town of Pinedale (Figure 1). It is one of the largest natural gas fields in the United States with ultimate recoverable reserves estimated to be about 39 trillion cubic feet (tcf) of methane-rich natural gas. Despite the huge gas reserves, the field's productive areal extent is relatively small as it is only about 30 mi (48 km) long and less than 5 mi (8 km) wide. The field covers an area of about 84 mi2 (220 km2). In this sense, it is a very concentrated gas resource.

Figure 1 Location of the Pinedale field in the northern part of the Green River Basin just south of Pinedale, Wyoming. The field has a relatively small areal extent for its reserves, which are estimated at about 39 tcf of recoverable gas.

[[File:M107FG1.jpg|thumb|300px|Figure 1 Location of the Pinedale field in the northern part of the Green River Basin just south of Pinedale, Wyoming. The field has a relatively small areal extent for its reserves, which are estimated at about 39 tcf of recoverable gas.]]

Production at Pinedale comes from the Lance Pool, which is nearly 6000 ft (1800 m) thick and consists of multiple stacked discontinuous Upper Cretaceous Lance and upper Mesaverde sandstones and siltstones that were predominantly deposited by fluvial processes and are encased in shales and mudstones. The reservoir rocks in Pinedale field occur at depths of about 8500 to 14,500 ft (2600–4400 m) and are tight with fairly low porosity (mostly <10%) and very low (micro-Darcy) permeability. The tight nature of these reservoir rocks makes it difficult for gas to move laterally and vertically for significant distances. As a result, it is necessary to conduct multistage hydraulic fracturing in all of the field's wells to create pathways for the gas to enter the wellbores at commercial rates.

Production at Pinedale comes from the Lance Pool, which is nearly 6000 ft (1800 m) thick and consists of multiple stacked discontinuous Upper Cretaceous Lance and upper Mesaverde sandstones and siltstones that were predominantly deposited by fluvial processes and are encased in shales and mudstones. The reservoir rocks in Pinedale field occur at depths of about 8500 to 14,500 ft (2600–4400 m) and are tight with fairly low porosity (mostly <10%) and very low (micro-Darcy) permeability. The tight nature of these reservoir rocks makes it difficult for gas to move laterally and vertically for significant distances. As a result, it is necessary to conduct multistage hydraulic fracturing in all of the field's wells to create pathways for the gas to enter the wellbores at commercial rates.

The continuity provided by year-round access led to significant performance improvements in drilling and completion efficiencies. Average drilling times have dropped from more than 60 days per well in the early 2000s to less than 12 days per well in 2013. In recent years, some wells have even been drilled to depths of over 14,000 ft (4300 m) in less than nine days (Figure 2).

The continuity provided by year-round access led to significant performance improvements in drilling and completion efficiencies. Average drilling times have dropped from more than 60 days per well in the early 2000s to less than 12 days per well in 2013. In recent years, some wells have even been drilled to depths of over 14,000 ft (4300 m) in less than nine days (Figure 2).

Figure 2 Average drill times from spud to attaining total depth (blue bars) for wells drilled by QEP in Pinedale field. With improved drill bits, mud systems, and crew efficiency, drill times decreased by more than 80% between 2003 and 2013. Also shown are the number of wells drilled each year (brown bars) and the wells per rig per year (purple line). The green box shows the record well drilled in just 8.6 days in 2012. Data in part from QEP Resources investor relations presentation (http://media.corporate-ir.net/media_files/IROL/23/237732/QEP1Q13OpsSlides.pdf accessed July 3, 2013).

[[File:M107FG2.jpg|thumb|300px|Figure 2 Average drill times from spud to attaining total depth (blue bars) for wells drilled by QEP in Pinedale field. With improved drill bits, mud systems, and crew efficiency, drill times decreased by more than 80% between 2003 and 2013. Also shown are the number of wells drilled each year (brown bars) and the wells per rig per year (purple line). The green box shows the record well drilled in just 8.6 days in 2012. Data in part from QEP Resources investor relations presentation (http://media.corporate-ir.net/media_files/IROL/23/237732/QEP1Q13OpsSlides.pdf accessed July 3, 2013).]]

The decline in drill times can be attributed to a number of factors including fit-for-purpose rigs, improved drill-bit technology, drilling wells with oil-based mud instead of water-based mud, consistently trained and experienced crews, use of down-hole mud-motors and steerable assemblies, new slim-hole well designs, multiwell pad drilling, and removing steps from the critical path of the drilling rig. Similar performance gains have been seen on the completions side where wells once took more than a month to complete. Now a pair of wells can be completely fracked with over 20 frack stages per well within four or five days. These efficiencies have given Pinedale operators a cost advantage that has expanded the economic limits of the field and allowed for full field development through high density drilling.

The decline in drill times can be attributed to a number of factors including fit-for-purpose rigs, improved drill-bit technology, drilling wells with oil-based mud instead of water-based mud, consistently trained and experienced crews, use of down-hole mud-motors and steerable assemblies, new slim-hole well designs, multiwell pad drilling, and removing steps from the critical path of the drilling rig. Similar performance gains have been seen on the completions side where wells once took more than a month to complete. Now a pair of wells can be completely fracked with over 20 frack stages per well within four or five days. These efficiencies have given Pinedale operators a cost advantage that has expanded the economic limits of the field and allowed for full field development through high density drilling.

Simultaneous operations (SIMOPS) are also now being done by all the major operators in Pinedale field with drilling, hydraulic fracturing, and facilities installations occurring at the same time (Figure 3). In order to fully develop the resource, wells are being drilled on dense spacing of as little as five acres per well. This makes Pinedale field one of the first places with such high-density pad drilling. Well bores are gently S-shaped and are drilled on pads to reduce the surface disturbance, which allows the development of a relatively large subsurface volume from a relatively small surface area (Figure 4).

Simultaneous operations (SIMOPS) are also now being done by all the major operators in Pinedale field with drilling, hydraulic fracturing, and facilities installations occurring at the same time (Figure 3). In order to fully develop the resource, wells are being drilled on dense spacing of as little as five acres per well. This makes Pinedale field one of the first places with such high-density pad drilling. Well bores are gently S-shaped and are drilled on pads to reduce the surface disturbance, which allows the development of a relatively large subsurface volume from a relatively small surface area (Figure 4).

Figure 3 Simultaneous operations being conducted in Pinedale field with drilling, fracking, setting of surface pipe, and facilities installation all occurring concurrently.

[[File:M107FG3.jpg|thumb|300px|Figure 3 Simultaneous operations being conducted in Pinedale field with drilling, fracking, setting of surface pipe, and facilities installation all occurring concurrently.]]

Figure 4 High-density pad drilling allows development of a large subsurface volume of the gas resource with minimal impact to the surface environment.

[[File:M107FG4.jpg|thumb|300px|Figure 4 High-density pad drilling allows development of a large subsurface volume of the gas resource with minimal impact to the surface environment.]]

==Pad drilling in pinedale field==

==Pad drilling in pinedale field==

Pad drilling along with timely reclamation has allowed all Pinedale field operators to reduce disturbance of the land. As field development has progressed and the number of wells per pad increased, the disturbance per well has continued to decline. Surface disturbance per well is now less than one acre on some multiwell pads (Figure 5).

Pad drilling along with timely reclamation has allowed all Pinedale field operators to reduce disturbance of the land. As field development has progressed and the number of wells per pad increased, the disturbance per well has continued to decline. Surface disturbance per well is now less than one acre on some multiwell pads (Figure 5).

Figure 5 Total disturbance per well and long-term disturbance per well continue to decline with improved drilling techniques such as the pad drilling now being used to develop Pinedale field.

[[File:M107FG5.jpg|thumb|300px|Figure 5 Total disturbance per well and long-term disturbance per well continue to decline with improved drilling techniques such as the pad drilling now being used to develop Pinedale field.]]

==Environmental concerns==

==Environmental concerns==