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Integration of fiber optic data with reservoir modeling and analysis: a case study in the Wolfcamp shale
Bourdon, Nicole
Bourdon, Nicole
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2023
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Abstract
The ability to produce hydrocarbons from low permeability shale reservoirs has been unlocked by advancements in horizontal drilling and hydraulic fracturing stimulation techniques. Hydrocarbon production in the Delaware Basin within the Permian Basin has been increased as unconventional reservoirs have begun to be infilled with multiple horizontal wells. The differences between conventional reservoirs and unconventional shale reservoirs have necessitated changes in asset evaluation and the deployment of new technologies to analyze the production behavior of unconventional wells at the time of stimulation and throughout the production lifetime. Fiber optic technology has been utilized to characterize and visualize the production from unconventional shale reservoirs. Distributed acoustic signals (DAS) and distributed temperature signals (DTS) can be collected and analyzed through the fiber optic line installed permanently into the well. DAS/DTS can be used to evaluate flow behavior and reservoir properties during completions and over the production lifetime of the well.
In this thesis, production and fiber optic data were used to analyze hydraulic fracture performance, flow behavior, and communication between wells. The data was sourced from seven horizontal wells located in the Wolfcamp shale lithology within the Delaware Basin operated by Coterra Energy. Commercial software is used to build a seven-well multistage hydraulic fracturing model and to perform rate transient analysis (RTA). Petrophysical logs, geosteering data, and petrophysical data provided on the fiber optic well were used to build the model and place the seven wellbores within the grid. The model showed that wells located in two different Wolfcamp A landing zones were communicating with each other both vertically between landing zones and within the same landing zone. The proppant and fluid pumped down into the stimulated well traveled through the reservoir into the near-wellbore region of the other wells in the development. The final model results showed that there was little uncontacted rock existing between the hydraulically fractured wellbores. The 4H well within the development had a temperature and acoustic fiber optic line permanently installed behind the casing. The DAS and DTS data from this line was used to evaluate how many of the fracturing stages are contributing to production in isolation from one another. The DAS data was taken only during the time of completions and flowback, but the DTS data was taken for two years of production. Communication between the stages in the 4H lateral was seen in the DAS/DTS data that suggested that stages were communicating with each other through failed plugs, annular channels, and through the rock and natural fractures of the formation. 45 percent of the nominal stages were shown to be in communication with other stages in the lateral. The DAS/DTS data also showed that the 4H fiber optic monitoring well was in communication with each of the five wells that were being stimulated around the same time. Hydraulic fracture order and proximity to the 4H fiber optic monitor well were determined to be causes for different types of communication and the number of communication events detected.
RTA was used to evaluate reservoir properties including permeability, area of reservoir drained, and hydraulic fracture effective length. Two sets of RTA were performed. An initial RTA was performed using the nominal number of stages. After evaluating the fiber optic data from the time of completions and the long term DTS data, the RTA was re-done with the effective number of stages. The effective number of stages was derived from the DAS/DTS data showing communication events between 45 percent of stages within the 4H lateral. The RTA completed with the effective number of stages was more accurate and better matched with the known reservoir permeability gathered from the DFITs performed on the wells within the development. The permeabilities calculated from the effective stage RTA range from 0.0016 - 0.0727 md. The drainage area of the wells ranged from 110 acres to 890 acres as determined by the effective stage RTA. The effective stage RTA results on permeability better matched the Delaware Basin permeabilities for other developments. Fiber data taken during the time of completions and throughout the production life of the well was determined to be beneficial in evaluating flow behavior and reservoir properties in horizontally drilled and hydraulically fractured wells.
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