coiled tubing
G L O B A L E X P L O R AT I O N & P R O D U C T I O N N E W S
www.eandp.info
•
T E C H N O L O G Y U P D AT E S
A Hart Energy Publication
•
A N A LY S I S
March 2008
COILED TUBING
OPERATIONS Electromagnetics Integration increases understanding
Stimulation Mapping improves efficiency
Unconventional Gas-Shale Technology increases production
SPECIAL BONUS: Annual Drill Bit Records
Stimulation
Simultaneous fracturing takes off Enormous multiwell fracs maximize exposure to shale reservoirs, achieving more production sooner. AUTHORS Gary W. Schein and Stephanie Weiss, BJ Services Company
L
arge-volume slickwater fracture stimulation has proven very successful in naturally fractured shale reservoirs such as the Barnett Shale of North Texas, the Fayetteville Shale in Arkansas, the Marcellus Shale in Appalachia Basin and many other shale reservoirs. These shales require hydraulic fracture stimulation in order to obtain commercial production. The characteristics and mineralogical properties of the shale allow for the creation of complex fracture geometries that contact large surface areas during fracture stimulation, which all contribute to production. The evolution of the development and transition from vertical wells to horizontal wells has been key to enhancing the potential reserve recovery in many areas. This has been particularly important in urban environments where drill sites are limited. Typically, wells in these shales are long horizontal laterals ranging from as little as 1,800 to more than 4,000 ft (549 to more than 1,220 m). These wells are typically fracture-stimulated with large, multistage treatments that reach deep into the formation and potentially interconnect the natural fracture network to contact as much reservoir rock as possible. A recent completion trend in the North Texas Barnett, Arkansas Fayetteville shales and others such as the Woodford Shale in Oklahoma is the technique of simultaneously fracturing two or more parallel wellbores. These enormous “simo-frac” operations are designed to take advantage of communication between wells to
E&P | March 2008
Figure 1. BJ Services pump trucks and equipment converge on three Barnett Shale wells for a simultaneous fracture stimulation treatment. (Graphics courtesy of BJ Services Company) Pump rates at the lower end of the range are aimed at helping contain fracture height growth in “non-core” areas that do not have a natural barrier to prevent accidentally breaching the porous, wet Ellenberger formation. Hydraulic fractures created during treatments in these shales cannot be Slickwater designs considered the same as conventional A typical Barnett shale slickwater frac fractures in that typical two-wing fracture involves pumping 500,000 to 1 million geometry does not occur. The fracture gal of fluid and 250,000 to 700,000 lb of characterization is much more complex, proppant at 50 to 80 bbl/min in each of as has been evidenced through utilizafive to seven stages. The actual treatment tion of microseismic technology to “fracdesign from the standpoint of exact ture-map” the stimulation treatments. fluid and proppant volumes can vary The result of microseismic mapping has based on the well’s location — whether shown that fracture stimulation in the in the “core” or “non-core” area — or Barnett can create a fracture “fairway” certainly depending upon proximity to with broad extent and length and with water-bearing intervals (Ellenberger) multiple fracture orientations. below the Barnett. In many cases, treatExperience has shown that these large ments start with 100 mesh or 40/70 stimulation treatments can communimesh proppant because the small particate through the fracture system to offcle diameter allows the low-viscosity set wells as far as 1,800 ft (549 m) away, water to carry it deep into the formation. resulting in improved production on Most treatments typically tail-in with a the stimulated well — but it may also smaller volume of 20/40 mesh proppant cause reduced production at a producto maximize near-wellbore conductivity. ing offset or even kill the offset. This is
enhance the degree and intensity of fracturing in the area between the well bores, maximizing communication with the natural fractures. The concept sounds good in theory, but the ultimate proof is in the economic return.
www.eandp.info
Stimulation
important because in many cases parallel well bores are being drilled in the Barnett, with spacing between the laterals ranging from 500 to 1,000 ft (152 to 305 m) apart, depending upon lease arrangement. The simo-frac technique takes advantage of the predicted communication to enhance the degree and uniformity of inter-well fracturing, thereby expanding the fracture network area. Although it may not be evident during the stimulation of the parallel well bores, the potential effect of stress and stress shadowing suggests potential increases in the additional reservoir rock contacted not only away from the well bore but also between the well bores. Another advantage to this process, particularly within the urban environment and in areas with multiple wells on a single pad, is that this process allows wells to be completed more quickly, thus helping improve well economics. For example, an early 2006 simo-frac operation stimulated two neighboring wells in Fort Worth, Texas. The wells were drilled from one pad, about 30 ft (10 m) apart, with roughly parallel horizontal trajectories ending about 1,000 ft apart. The proximity of the wells suggested that sequential stimulation might result in fluid communication from the second well effectively killing the first well. In addition, the two wells could be completed faster and more efficiently. Furthermore, a simultaneous fracturing operation would maximize the fracture network created between the wells and bring both wells on sales faster than sequential operations. The job pumped as designed with a total of approximately 3.5 million lb of proppant and 250,000 bbl of slickwater fluid in nine stages on the wells (four stages on one well and five on the other). After treatment, both wells produced at significantly higher rates than any offsets; one produced an average of almost 9 MMcf/d of gas for more than 30 days, compared with offsets in the 2 MMcf/d to 5 MMcf/d range. A production com-
Figure 2. Stimulating parallel wells simultaneously maximizes both wells’ production potential compared with individually fractured offsets. parison can be seen in Figure 2. In another example, during late summer/early fall 2007, BJ performed simultaneous fracture stimulations on three roughly parallel horizontal well bores north of Fort Worth. The enormous simultaneous fracturing operations involved 29 pump trucks with a total of more than 55,000 hydraulic horsepower pumping 351,000 bbl of fluid and nearly 5.5 million lb of sand. The resultant production from all three wells is among the highest in the area. In December, the company pumped simultaneous fracturing operations on three wells in the Fayetteville shale of Arkansas. Three of the company’s districts provided high-rate (+100 bbl/min) frac fleets to pump more than 6.6 million pounds of sand over some 22 hours. Three treatment vans — one for each frac fleet — stayed in constant communication so engineers could fine-tune each stage on each well during the course of pumping. The service company has performed simultaneous fracture stimulations to complete 12 additional sets of wells, including three triple fracs using simultaneous operations. Planning is underway for more operations, including a potential for quad frac in the not-toodistant future.
Logistics are critical Careful planning and logistics are critical. First, some locations require creative arrangements in order to squeeze the necessary equipment into the allocated space so it can function as required. Second, the fluid and sand volumes must be arranged well in advance. The service company and operator must work closely together though all phases of the planning, drilling and completion process to ensure an optimum treatment. It is particularly important to develop a plan so the proper amount of treatment fluid will be available because these simultaneous treatments require massive volumes of water. In addition, the location must be configured to allow for continuous supply of chemicals, fuel and proppant for the treatments. For example, before starting the Arkansas operation, 76 sand trucks were lined up at location, waiting to be off-loaded “on the fly” over the 22hour pump time. As with any fracture stimulation, candidate evaluation is important to achieving a successful result. Consideration must be given to such variables as the reservoir characteristics, well spacing, well configuration and well azimuth, as well as several other factors to maximize the potential for success.
Copyright, Hart Energy Publishing, 1616 S. Voss, Ste. 1000, Houston, TX 77057 USA (713)260-6400, Fax (713) 840-8585
Unlocking gas from your reservoir needs the right touch.
Unconventional wells require unconventional solutions. The easy formations have been drilled. Natural gas from unconventional sources is the new reality for operators in N. America today. BJ Services earned its reputation of success exploiting shale gas and CBM reserves. BJ field crews deliver best-in-class hydraulic fracturing services that benefit from BJ innovations like low- and no-polymer frac fluids and exclusive LiteProp™ ultra-lightweight proppants that can be placed with slick water. Plus, as the only major pumping services company with integrated production chemical capabilities, BJ offers StimPlus™ services to protect against long-term production problems. The latest addition to the BJ unconventional arsenal is DirectStim™ services. DirectStim service provides direct and precise placement of stimulation fluid throughout a horizontal wellbore, resulting in greater stimulation coverage and greater access to reserves. For unconventional gas, BJ has what it takes to help your development strategy succeed. NYSE: BJS
BJ Services Company
713.462.4239
bjservices.com
www.eandp.info
•
T E C H N O L O G Y U P D AT E S
A Hart Energy Publication
•
A N A LY S I S
March 2008
COILED TUBING
OPERATIONS Electromagnetics Integration increases understanding
Stimulation Mapping improves efficiency
Unconventional Gas-Shale Technology increases production
SPECIAL BONUS: Annual Drill Bit Records
Stimulation
Simultaneous fracturing takes off Enormous multiwell fracs maximize exposure to shale reservoirs, achieving more production sooner. AUTHORS Gary W. Schein and Stephanie Weiss, BJ Services Company
L
arge-volume slickwater fracture stimulation has proven very successful in naturally fractured shale reservoirs such as the Barnett Shale of North Texas, the Fayetteville Shale in Arkansas, the Marcellus Shale in Appalachia Basin and many other shale reservoirs. These shales require hydraulic fracture stimulation in order to obtain commercial production. The characteristics and mineralogical properties of the shale allow for the creation of complex fracture geometries that contact large surface areas during fracture stimulation, which all contribute to production. The evolution of the development and transition from vertical wells to horizontal wells has been key to enhancing the potential reserve recovery in many areas. This has been particularly important in urban environments where drill sites are limited. Typically, wells in these shales are long horizontal laterals ranging from as little as 1,800 to more than 4,000 ft (549 to more than 1,220 m). These wells are typically fracture-stimulated with large, multistage treatments that reach deep into the formation and potentially interconnect the natural fracture network to contact as much reservoir rock as possible. A recent completion trend in the North Texas Barnett, Arkansas Fayetteville shales and others such as the Woodford Shale in Oklahoma is the technique of simultaneously fracturing two or more parallel wellbores. These enormous “simo-frac” operations are designed to take advantage of communication between wells to
E&P | March 2008
Figure 1. BJ Services pump trucks and equipment converge on three Barnett Shale wells for a simultaneous fracture stimulation treatment. (Graphics courtesy of BJ Services Company) Pump rates at the lower end of the range are aimed at helping contain fracture height growth in “non-core” areas that do not have a natural barrier to prevent accidentally breaching the porous, wet Ellenberger formation. Hydraulic fractures created during treatments in these shales cannot be Slickwater designs considered the same as conventional A typical Barnett shale slickwater frac fractures in that typical two-wing fracture involves pumping 500,000 to 1 million geometry does not occur. The fracture gal of fluid and 250,000 to 700,000 lb of characterization is much more complex, proppant at 50 to 80 bbl/min in each of as has been evidenced through utilizafive to seven stages. The actual treatment tion of microseismic technology to “fracdesign from the standpoint of exact ture-map” the stimulation treatments. fluid and proppant volumes can vary The result of microseismic mapping has based on the well’s location — whether shown that fracture stimulation in the in the “core” or “non-core” area — or Barnett can create a fracture “fairway” certainly depending upon proximity to with broad extent and length and with water-bearing intervals (Ellenberger) multiple fracture orientations. below the Barnett. In many cases, treatExperience has shown that these large ments start with 100 mesh or 40/70 stimulation treatments can communimesh proppant because the small particate through the fracture system to offcle diameter allows the low-viscosity set wells as far as 1,800 ft (549 m) away, water to carry it deep into the formation. resulting in improved production on Most treatments typically tail-in with a the stimulated well — but it may also smaller volume of 20/40 mesh proppant cause reduced production at a producto maximize near-wellbore conductivity. ing offset or even kill the offset. This is
enhance the degree and intensity of fracturing in the area between the well bores, maximizing communication with the natural fractures. The concept sounds good in theory, but the ultimate proof is in the economic return.
www.eandp.info
Stimulation
important because in many cases parallel well bores are being drilled in the Barnett, with spacing between the laterals ranging from 500 to 1,000 ft (152 to 305 m) apart, depending upon lease arrangement. The simo-frac technique takes advantage of the predicted communication to enhance the degree and uniformity of inter-well fracturing, thereby expanding the fracture network area. Although it may not be evident during the stimulation of the parallel well bores, the potential effect of stress and stress shadowing suggests potential increases in the additional reservoir rock contacted not only away from the well bore but also between the well bores. Another advantage to this process, particularly within the urban environment and in areas with multiple wells on a single pad, is that this process allows wells to be completed more quickly, thus helping improve well economics. For example, an early 2006 simo-frac operation stimulated two neighboring wells in Fort Worth, Texas. The wells were drilled from one pad, about 30 ft (10 m) apart, with roughly parallel horizontal trajectories ending about 1,000 ft apart. The proximity of the wells suggested that sequential stimulation might result in fluid communication from the second well effectively killing the first well. In addition, the two wells could be completed faster and more efficiently. Furthermore, a simultaneous fracturing operation would maximize the fracture network created between the wells and bring both wells on sales faster than sequential operations. The job pumped as designed with a total of approximately 3.5 million lb of proppant and 250,000 bbl of slickwater fluid in nine stages on the wells (four stages on one well and five on the other). After treatment, both wells produced at significantly higher rates than any offsets; one produced an average of almost 9 MMcf/d of gas for more than 30 days, compared with offsets in the 2 MMcf/d to 5 MMcf/d range. A production com-
Figure 2. Stimulating parallel wells simultaneously maximizes both wells’ production potential compared with individually fractured offsets. parison can be seen in Figure 2. In another example, during late summer/early fall 2007, BJ performed simultaneous fracture stimulations on three roughly parallel horizontal well bores north of Fort Worth. The enormous simultaneous fracturing operations involved 29 pump trucks with a total of more than 55,000 hydraulic horsepower pumping 351,000 bbl of fluid and nearly 5.5 million lb of sand. The resultant production from all three wells is among the highest in the area. In December, the company pumped simultaneous fracturing operations on three wells in the Fayetteville shale of Arkansas. Three of the company’s districts provided high-rate (+100 bbl/min) frac fleets to pump more than 6.6 million pounds of sand over some 22 hours. Three treatment vans — one for each frac fleet — stayed in constant communication so engineers could fine-tune each stage on each well during the course of pumping. The service company has performed simultaneous fracture stimulations to complete 12 additional sets of wells, including three triple fracs using simultaneous operations. Planning is underway for more operations, including a potential for quad frac in the not-toodistant future.
Logistics are critical Careful planning and logistics are critical. First, some locations require creative arrangements in order to squeeze the necessary equipment into the allocated space so it can function as required. Second, the fluid and sand volumes must be arranged well in advance. The service company and operator must work closely together though all phases of the planning, drilling and completion process to ensure an optimum treatment. It is particularly important to develop a plan so the proper amount of treatment fluid will be available because these simultaneous treatments require massive volumes of water. In addition, the location must be configured to allow for continuous supply of chemicals, fuel and proppant for the treatments. For example, before starting the Arkansas operation, 76 sand trucks were lined up at location, waiting to be off-loaded “on the fly” over the 22hour pump time. As with any fracture stimulation, candidate evaluation is important to achieving a successful result. Consideration must be given to such variables as the reservoir characteristics, well spacing, well configuration and well azimuth, as well as several other factors to maximize the potential for success.
Copyright, Hart Energy Publishing, 1616 S. Voss, Ste. 1000, Houston, TX 77057 USA (713)260-6400, Fax (713) 840-8585
Unlocking gas from your reservoir needs the right touch.
Unconventional wells require unconventional solutions. The easy formations have been drilled. Natural gas from unconventional sources is the new reality for operators in N. America today. BJ Services earned its reputation of success exploiting shale gas and CBM reserves. BJ field crews deliver best-in-class hydraulic fracturing services that benefit from BJ innovations like low- and no-polymer frac fluids and exclusive LiteProp™ ultra-lightweight proppants that can be placed with slick water. Plus, as the only major pumping services company with integrated production chemical capabilities, BJ offers StimPlus™ services to protect against long-term production problems. The latest addition to the BJ unconventional arsenal is DirectStim™ services. DirectStim service provides direct and precise placement of stimulation fluid throughout a horizontal wellbore, resulting in greater stimulation coverage and greater access to reserves. For unconventional gas, BJ has what it takes to help your development strategy succeed. NYSE: BJS
BJ Services Company
713.462.4239
bjservices.com
