The Channel Fracturing technique was introduced have been pumped with this novel technique since realized over conventional completion methodologies. each treatment.The successful introduction of the Channel Fracturing technique prompted a new attempt to optimize completion practices by eliminating immediate flowback of each stage A field study was conducted to evaluate the performance of combined with sequential fracturing treatments with treating pressure data was gathered and compared against a sample of 18 placement with immediate flowback after each stage.Results indicate that the Channel Fracturing technique increased production Production gains were obtained without the Improvements in operational efficiency due to continuous fracturing operations and avoidance of screen reduction in overall operational costs of 18%. stimulation within a single wellbore can mit logistics and reduce the overall impact to the hydraulic fracturing footprint. multi-stage Channel Fracturing without flowback in between st wells in the Jonah field.was introduced for multi-stage well stimulation in the Jonah Field in 2010. 622 stages with this novel technique since. Production increases by as much as 27% (Johnson et al., 2011) realized over conventional completion methodologies. In this previous study, each stage was flowed back immediately afterThe successful introduction of the Channel Fracturing technique prompted a new attempt to optimize completion practices by flowback of each stage as a necessary step to sustain production performance goals A field study was conducted to evaluate the performance of five new wells stimulated with the Channel Fracturing technique combined with sequential fracturing treatments without flowback in between stages. Gas production, fluid flowback and gathered and compared against a sample of 18 offset wells stimulated with conventional proppant ack after each stage.annel Fracturing technique increased production by up to 28% with respe the occurrence of screen-outs for the wells stimulated with Channel Fracturing. ency due to continuous fracturing operations and avoidance of screen operational costs of 18%. Results show that the combination of Channel Fracturing mitigate previously documented production performance issues, reduce operational logistics and reduce the overall impact to the hydraulic fracturing footprint. By virtue of these benefits, well stimulation via stage Channel Fracturing without flowback in between stages has been adopted as a completion practice of choice for
The hydraulic Channel Fracturing technique relies on the engineered creation of a network of open channels within the proppant pack, which provides for highly conductive paths for the flow of fluids from the reservoir to the wellbore. This paper provides a comprehensive summary of the implementation of this technique in ultra-low permeability, gas-bearing formations. The Lance formation in the Jonah field near Pinedale, Wyoming was selected for this study. This formation comprises fluvial sand bodies with 0.0005 to 0.05 mD permeability and 35 to 55% gas saturation. The formation requires hydraulic fracturing for economic production. Key historical issues for the stimulation of this formation using gelled fluids and sand as proppant are limited fluid recovery and consequential formation and fracture conductivity impairments. Slick-water treatments have rendered moderate gains in production mainly in low-prospect zones with some occurrence of near-wellbore screen-outs. Moderate increases in production from using ceramic proppants have been gained at the expense of significant increase in stimulation costs. Hydrocarbon production, treating pressure and fracturing fluid recovery data from a thirteen-well campaign in the Jonah field are summarized in the manuscript. Results indicate that the implementation of the channel fracturing technique increased initial gas production and estimated recovery over conventional fracturing methodologies. Positive features that were also observed during this campaign such as reduced net pressure increase estimates from pre- and post-frac shut-in pressure measurements, reduced tendency for vertical fracture growth and elimination of near-wellbore screen-outs are also reported and discussed. It is concluded that the Channel Fracturing technique is a viable alternative to conventional fracturing methods for more efficient and effective stimulation of complex tight gas formations.
A well which was drilled in the Pronghorn formation of the Williston Basin had significant trouble during the cementing process. While the lateral length was 11,103 feet, only the 9,296 feet of the lateral closest to the toe had adequate cement to provide the isolation needed for hydraulic fracture stimulation. An integrated solution with evaluation of well integrity and novel diversion material used over the remaining 1,807 feet of the lateral to generate multiple hydraulic fractures was proposed and results were confirmed with production log evaluation. After using an ultrasonic imaging logging tool conveyed via tractor to determine the point at which the cement isolation became unreliable, the appropriate completion was designed. The first 33 stages of the stimulation were done using a standard plug and perf technique. The last 1,807 feet of the lateral were completed in two intervals with only one additional bridge plug. The two intervals were each stimulated with seven hydraulic fracturing stages and six diversion pills consisting of a proprietary blend of degradable materials. While more stages were pumped in the heel section, the same amount of proppant per foot of lateral was used as in the larger conventionally completed toe section. The 14 stages pumped in the heel portion of the lateral showed that in both intervals, the instantaneous shut-in pressures at the end of each one of them increased by 2,300 psi and 340 psi respectively. This increase is consistent with fractures initiating at lower pressure intervals, and then being diverted to higher pressure, unstimulated areas. Well production was evaluated with a production log capable of identifying multiphase holdup along the lateral. This evaluation showed that 42% of the total oil production was coming from the 18% of the lateral which was stimulated using the degradable diversion material. The application of this degradable diversion material in poorly cemented or un-cemented lateral sections in order to create a more uniform distribution of hydraulic fractures can significantly improve both completion efficiency and hydrocarbon production.
A new sequenced fracturing technique is presented that allows for further increases in reservoir contact in the developed multi-stage completion scheme utilized in the Williston Basin -cemented liner, plug and perforation. The performance of this composite diverter (or pill), with respect to stimulating more clusters and the resulting production, is evaluated using a detailed workflow in which real-time pressure observations are made, data is collected and analyzed using fracturing simulation tools, and production is compared with that of offset wells stimulated with conventional propped fracturing designs.The success of the diversion will be presented as results from such analytic methods as observation of surface pressure responses to the pill's placement into the formation, rate step-down tests for analysis of near-wellbore effects, and statistical evaluation of production data. The step-down tests provide comparisons of how many perforation clusters are stimulated before and after the pill, which will illustrate both the performance of plugging and diversion and the comparison to fracture counts in conventionally stimulated wells. Production comparisons between the test wells and offsets give an indication of increased reservoir contact resulting from diversion, and results from tracer collection illustrate which intervals (between diverter-treated and conventional) are contributing to production.Over the 102 intervals in which the sequenced fracturing technique was implemented on the four cemented, plug-and-perf wells, significant diversion was observed in 97 of those, a 95% success rate. The success criteria for this condition were based on observation of increases in surface treating pressure at the constant-rate pill placement into the formation. Changes in instantaneous shut-in pressures (ISIP) before versus after the pill and overlays of treating pressure before and after the pill were also analyzed as metrics of diversion success, and it was found that 81% of test intervals met the success criteria for ⌬ISIP.Step-down tests indicated a reduction in perforations taking fluid from before the pill to after its placement, which supports the theory that this technique was effective in plugging fractures initially taking fluid.The success of fracture plugging and diversion was reinforced by analysis of the near wellbore effects obtained from the step-down tests, which illustrated that the tortuosity reduction achieved by acid following the pill was significantly greater than the reduction observed during the placement of the first acid spear (following the ball) -indicating that new perforation clusters were being treated after the pill.
This paper describes design methodology, execution details, and production results of stimulation treatments in openhole sections of laterals in the Williston Basin. It will be demonstrated that a sequenced fracturing technique utilizing appropriate hydraulic fracturing design with proprietary diversion material can effectively stimulate 900 to 2,500 ft. long barefoot intervals of horizontal laterals drilled in the Bakken group of formations. In order to achieve multiple hydraulic fractures in an openhole environment, it is necessary to have a diversion material that bridges effectively in the current fracture, and can withstand enough pressure to allow initiation and propagation of subsequent fractures. In this case, a blend of four distinct particle sizes and fibers made from degradable synthetic polymer was pumped following each fracturing stage in order to divert subsequent treatments from previously created fractures. The number of stimulation stages in the design has been selected based on openhole interval length and the number of designed fractures. Two wells have been completed in the Williston Basin with TVD's between 9,800 and 11,200 ft. and fracture gradients between 0.85 and 0.97 psi/ft. Due to operational difficulties while running casing, approximately 900 ft and 2,500 ft of the toe sections were left as an openhole completion. This represented 10% and 29% of respective lateral lengths. Both openhole intervals were stimulated with a bullhead sequence fracturing technique utilizing 11 and 24 stimulation stages respectively, pumped sequentially and separated by diversion pills. During stimulation operations the instantaneous shut-in pressures (ISIPs) were used as an indicator of diversion efficiency. Based on the overall trend it can be concluded that the early fractures initiated in the lowest stress areas and then were diverted to higher stress sections reaching the highest local fracture gradients by the end of the treatment. The ISIP increases were 1,400 and 2,100 psi for the respective laterals. The values of ISIP in the openhole intervals correspond very closely to the lowest and highest pressures seen in the cased portion of respective laterals. This is a strong indication that multiple fractures were created over the lengthy openhole intervals. Production results at 270 days and 100 days indicate that these wells are among the top producers in their areas. This paper describes the first application of the sequence fracturing technique in horizontal wells with openhole completions. The ability to create multiple fractures in an openhole environment without packers or other mechanical isolation opens options for improving operational efficiency in any un-cemented environment. This technique provides an alternative completion method for these types of wells which can lead to significant production improvement because no part of the drilled lateral is left unstimulated. Adding effective diversion to this type of completion could significantly increase the number of productive fractures that are created.
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