Case study of hydraulic fracture monitoring using multiwell integrated analysis based on low-frequency DAS data

2020 ◽  
Vol 39 (11) ◽  
pp. 794-800
Author(s):  
Masaru Ichikawa ◽  
Shinnosuke Uchida ◽  
Masafumi Katou ◽  
Isao Kurosawa ◽  
Kohei Tamura ◽  
...  
Keyword(s):  
Hydraulic Fracture ◽  
Fiber Optic ◽  
Low Frequency ◽  
Fracture Propagation ◽  
Propagation Direction ◽  
Integrated Analysis ◽  
Fiber Direction ◽  
Distributed Temperature Sensing ◽  
Fiber Optic Cable ◽  
Cumulative Strain

Distributed acoustic sensing (DAS) is an effective technique for hydraulic fracture monitoring. It can potentially constrain fracture propagation direction and time while monitoring strain perturbation, such as stress shadowing. In this study, we acquired passive DAS and distributed temperature sensing (DTS) data throughout the entire fracturing operations of adjacent production wells with varying offset lengths from the fiber-optic cable in the Montney tight gas area. We applied data processing techniques to the DAS data to extract low-frequency components (less than 0.5 Hz) and to construct the strain rate and cumulative strain maps for detecting responses related to fracture hits along the fiber-optic cable. We used low-frequency DAS (LF-DAS) results to estimate the fracture hit position and time, and in certain cases, to additionally estimate the fracture connection. By integrating LF-DAS results with DTS results, we detected the temperature changes around the compression response near the fracture hit position and time. Furthermore, we observed that timing of the fracture hit can be constrained more precisely by using high-frequency DAS data (greater than 10 Hz). We estimated the fracture propagation direction and speed from the estimated fracture hit position and time. The fracture propagation direction deviated slightly from a perpendicular line to the fiber direction. In addition, as estimated from the first fracture hit time, the fracture length and fluid injection volume had a proportional relationship. Due to challenges associated with the data, it is important to design data acquisition geometry and fracturing operations on the premise of acquiring LF-DAS data. It is also important to apply an additional noise reduction process to the data.

Fiber Optic Deployed Behind Cemented Casing in a Vertical Deep Tight Gas Well Used to Enhance Hydraulic Fracturing, Monitoring and Diagnostics

2021 ◽  
Author(s):  
Ahmed Rashid Al-Jahdhami ◽  
Juan Carlos Chavez ◽  
Shaima Abdul Aziz Al-Farsi
Keyword(s):  
Real Time ◽  
Surface Pressure ◽  
Hydraulic Fracture ◽  
Fiber Optic ◽  
Integrated Analysis ◽  
Radioactive Tracers ◽  
Distributed Temperature Sensing ◽  
Time Data ◽  
Fracture Geometry ◽  
Fracture Simulation

Abstract The use of fiber optic (FO) to obtain distributed sensing be it Distributed Temperature Sensing (DTS), Distributed Acoustic Sensing (DAS) or Distributed Strain Sensing (DSS) is a well & reservoir surveillance engineer's dream. The ability to obtain real-time live data has proven useful not only for production monitoring but during fracture stimulation as well. A trial the first of its kind in Petroleum Development Oman (PDO) used fiber optic cable cemented in place behind casing to monitor the fracture operations. Several techniques are used to determine fracture behaviour and geometry e.g. data fracs, step down test and after closure analysis. All these use surface pressure readings that can be limited due to uncertainty in friction pressure losses and the natural complexity in the formation leading to very different interpretations. Post frac data analysis and diagnostics also involves importing the actual frac data into the original model used to design the frac in order to calibrate the strains (tectonics), width exponent (frac fluid efficiency) and the relative permeability. Monitoring the frac using DAS and DTS proved critical in understanding a key component in fracture geometry; frac height. The traditional method to determine fracture height is to use radioactive tracers (RA). But these are expensive and the data only available after the job (after drilling the plugs and cleaning the wellbore). In contrast fiber optic can provide real time data throughout the frac stages including the proppant free PAD stage which tracers can't. The comparison of DTS and Radioactive Tracers showed very good agreement suggesting that DTS could replace RA diagnostic. Hydraulic fracture stimulation operations in well-xx was the first one of its kind to be monitored with fiber optic. The integrated analysis of the available logs allowed us to benchmark various information and gain confidence in the conclusions. This helped fine tune the model for future wells for a more optimized zonal targeting and hydraulic fracture design. In this paper we will share the detailed evaluation of the fracture propagation behaviour and how combining the fiber optic data with the surface pressure, pumping rates and tracer logs in conjunction with a fracture simulation platform where a detailed geomechanical and subsurface characterization data is incorporated to get a more accurate description of fracture geometry.

Hydraulic Fracturing Diagnostics Utilizing Near and Far-Field Distributed Acoustic Sensing DAS Data Correspondences

2021 ◽  
Author(s):  
Yinghui Wu ◽  
Robert Hull ◽  
Andrew Tucker ◽  
Craig Rice ◽  
Peter Richter ◽  
...  
Keyword(s):  
Hydraulic Fracture ◽  
Near Field ◽  
Fracture Propagation ◽  
Cost Effective ◽  
Hydraulic Fractures ◽  
Far Field ◽  
Distributed Temperature Sensing ◽  
Acoustic Sensing ◽  
Distributed Acoustic Sensing ◽  
Multiple Fibers

Abstract Distributed fiber-optic sensing (DFOS) has been utilized in unconventional reservoirs for hydraulic fracture efficiency diagnostics for many years. Downhole fiber cables can be permanently installed external to the casing to monitor and measure the uniformity and efficiency of individual clusters and stages during the completion in the near-field wellbore environment. Ideally, a second fiber or multiple fibers can be deployed in offset well(s) to monitor and characterize fracture geometries recorded by fracture-driven interactions or frac-hits in the far-field. Fracture opening and closing, stress shadow creation and relaxation, along with stage isolation can be clearly identified. Most importantly, fracture propagation from the near to far-field can be better understood and correlated. With our current technology, we can deploy cost effective retrievable fibers to record these far-field data. Our objective here is to highlight key data that can be gathered with multiple fibers in a carefully planned well-spacing study and to evaluate and understand the correspondence between far-field and near-field Distributed Acoustic Sensing (DAS) data. In this paper, we present a case study of three adjacent horizontal wells equipped with fiber in the Permian basin. We can correlate the near-field fluid allocation across a stage down to the cluster level to far-field fracture driven interactions (FDIs) with their frac-hit strain intensity. With multiple fibers we can evaluate fracture geometry, the propagation of the hydraulic fractures, changes in the deformation related to completion designs, fracture complexity characterization and then integrate the results with other data to better understand the geomechanical processes between wells. Novel frac-hit corridor (FHC) is introduced to evaluate stage isolation, azimuth, and frac-hit intensity (FHI), which is measured in far-field. Frac design can be evaluated with the correlation from near-field allocation to far-field FHC and FHI. By analyzing multiple treatment and monitor wells, the correspondence can be further calibrated and examined. We observe the far-field FHC and FHI are directly related to the activities of near-field clusters and stages. A leaking plug may directly result in FHC overlapping, gaps and variations in FHI, which also can be correlated to cluster uniformity. A near-far field correspondence can be established to evaluate FHC and FHI behaviors. By utilizing various completion designs and related measurements (e.g. Distributed Temperature Sensing (DTS), gauges, microseismic etc.), optimization can be performed to change the frac design based on far-field and near-field DFOS data based on the Decision Tree Method (DTM). In summary, hydraulic fracture propagation can be better characterized, measured, and understood by deploying multiple fibers across a lease. The correspondence between the far-field measured FHC and FHI can be utilized for completion evaluation and diagnostics. As the observed strain is directly measured, completion engineering and geoscience teams can confidently optimize their understanding of the fracture designs in real-time.

Integrated Analysis Combining Microseismic Mapping and Fiber-Optic Distributed Temperature Sensing (DTS)

2010 ◽  
Author(s):  
Eric Howard Holley ◽  
Ulrich Zimmer ◽  
Michael J. Mayerhofer ◽  
Etienne Samson
Keyword(s):  
Fiber Optic ◽  
Temperature Sensing ◽  
Integrated Analysis ◽  
Distributed Temperature Sensing

Measuring and tracking nighttime inversions within a forest canopy

2020 ◽  
Author(s):  
Bart Schilperoort ◽  
Miriam Coenders-Gerrits ◽  
Hubert Savenije
Keyword(s):  
Forest Canopy ◽  
Fiber Optic ◽  
Forest Understory ◽  
Forest Site ◽  
Distributed Temperature Sensing ◽  
Fiber Optic Cable ◽  
Vertical Temperature Profile ◽  
Flux Measurements ◽  
Response To Temperature ◽  
A Site

<p>One of the challenges of flux measurements above tall canopies, is that parts of the canopy can be decoupled from the atmosphere above. This decoupling can, for example, occur when the forest understory is colder than the air above, limiting exchange through convection. While concurrent above and below canopy eddy covariance (EC) measurements help with addressing the decoupling issue, these are still disconnected point measurements and do not show what is happening along the entire vertical profile. For this, Distributed Temperature Sensing (DTS) can give additional insights, as it can perform continuous temperature measurements along a vertically deployed fiber optic cable.</p><p>Measurements were performed at the ‘Speulderbos’ forest site in the Netherlands, where a 48 m tall measurement tower is located in a stand of 34 m tall Douglas Fir trees.  We measured a vertical temperature profile through the canopy using DTS (from the surface up to 32 m). The measurement frequency was ~0.5 Hz, with a vertical resolution 0.30 cm, and data was collected for two months. The fiber optic cable used had a diameter of 0.8 mm, allowing a sufficiently quick response to temperature changes. With this data we were able to detect the presence, height, and strength of inversions. The inversions appeared to occur mostly at night. The height of the inversion showed a bistable behavior, either staying around 1 m above the ground, or at approximately 16 m, which is just below the dense branches of the canopy.</p><p>By locating and tracking inversions within the canopy, decoupling events can be studied and explained in more detail. If vertical DTS profiles are available at a site, these can be used for filtering EC measurements as well. While more research will be needed before a wide application at flux sites is possible, this study can serve as a ‘proof-of-concept’ and demonstrates how vertical DTS profiles can help understand problematic flux sites.</p>

Technology Focus: Intelligent Operations (May 2021)

2021 ◽  
Vol 73 (05) ◽  
pp. 51-51
Author(s):  
Keshav Narayanan
Keyword(s):  
Pressure Wave ◽  
Fiber Optic ◽  
Digital Transformation ◽  
Distributed Temperature Sensing ◽  
Fiber Optic Cable ◽  
High Hydrogen ◽  
Digital Twin ◽  
Wireless Control ◽  
China National Petroleum Corporation ◽  
Remote Operations

The last year has seen people in many sectors unexpectedly confronting a new challenge—working remotely. Even before this, our industry has been trying to operate fields remotely (either partially or fully) and make operations smarter and more automated. Key drivers are to improve safety in operations, maximize production, and make operations more efficient. These efforts have been enabled by the rapidly changing technology landscape—in sophisticated acquisition and analysis of data and increased connectivity (from both fiber-optic and cellular networks). It also has been accelerated by the push across the industry to digitalize. We now acquire, process, and analyze much more detailed operations data and use the analysis to actively control wells and operations. This feature highlights recently presented papers that cover the following topics. How Digital Transformation Has Progressed. Paper OTC 30794 discusses similar efforts in other sectors, including marine/ship building and auto manufacturing. Paper SPE 200728 discusses use of a digital twin to improve operational efficiency in a mature brownfield setting (Brage Field in the Norwegian North Sea). Paper OTC 30488 describes extensible and scalable remote monitoring and control using a digital decision assistant. How Technology Has Enabled Data Acquisition and Analysis From Relatively New Sources [e.g., Distributed Temperature Sensing (DTS) or Distributed Acoustic Sensing]. Paper SPE 200826 describes seven DTS applications from around the world that monitor well integrity, stimulation, and injection profiles and identify gas, water, or sand production. Paper OTC 30442 and other papers from the Bokor field in Malaysia describe DTS data from fiber-optic cable behind casing in wells with smart completions. Papers IPTC 19574 and SPE 202349 show how pressure telemetry can enable wireless control of completions. The Path to Fully Remotely Operated Fields. Paper SPE 203461 discusses the design and execution of digitalization and remote operations in a new development area with high hydrogen sulfide (the Mender satellite field in the UAE). Paper SPE 202667 describes the applications for multiple autonomous robots controlled remotely. Digital transformation of work flows and operations clearly is happening across the industry and adding significant value. The next frontier on the digital transformation and Industry 4.0 journey might be to achieve step-change increases in oil and gas recovery factors. Recommended additional reading at OnePetro: www.onepetro.org. SPE 200728 - The Digitalization Journey of the Brage Digital Twin by Peter Kronberger, Wintershall, et al. OTC 30442 - Innovative Solution for IWAG Injection Monitoring Using Fiber-Optic Cable Cemented Behind Casing in an Intelligent Well: A First in Malaysia by Nur Faizah P. Mosar, Schlumberger, et al. SPE 202667 - Operations Room: A Key Component for Upscaling Robotic Solutions on Site by Jean-Michel Munoz, Total, et al. OTC 30488 - Machine-Learning-Enabled Digital Decision Assistant for Remote Operations by Vitor Alves da Cruz Mazzi, Intelie, et al. IPTC 19574 - Research and Application of Downhole Remote Wireless Control Technology Based on Gas Pressure Wave in Tubing by Mingge He, China National Petroleum Corporation, et al. SPE 202349 - Pressure Wave Downhole Communication Technique for Smart Zonal Water Injection by Quanbin Wang, China National Petroleum Corporation, et al.

scholarly journals Characterization of Diffuse Groundwater Inflows into Stream Water (Part II: Quantifying Groundwater Inflows by Coupling FO-DTS and Vertical Flow Velocities)

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2430 ◽  
Author(s):  
Hugo Le Lay ◽  
Zahra Thomas ◽  
François Rouault ◽  
Pascal Pichelin ◽  
Florentina Moatar
Keyword(s):  
Mass Balance ◽  
Fiber Optic ◽  
Stream Water ◽  
High Flow ◽  
Distributed Temperature Sensing ◽  
Fiber Optic Cable ◽  
Groundwater Inflow ◽  
Hyporheic Flow ◽  
Spatial Coverage ◽  
High Flow Period

Temperature has been used to characterize groundwater and stream water exchanges for years. One of the many methods used analyzes propagation of the atmosphere-influenced diurnal signal in sediment to infer vertical velocities. However, despite having good accuracy, the method is usually limited by its small spatial coverage. The appearance of fiber optic distributed temperature sensing (FO-DTS) provided new possibilities due to its high spatial and temporal resolution. Methods based on the heat-balance equation, however, cannot quantify diffuse groundwater inflows that do not modify stream temperature. Our research approach consists of coupling groundwater inflow mapping from a previous article (Part I) and deconvolution of thermal profiles in the sediment to obtain vertical velocities along the entire reach. Vertical flows were calculated along a 400 m long reach, and a period of 9 months (October 2016 to June 2017), by coupling a fiber optic cable buried in thalweg sediment and a few thermal lances at the water–sediment interface. When compared to predictions of hyporheic discharge by traditional methods (differential discharge between upstream and downstream of the monitored reach and the mass-balance method), those of our method agreed only for the low-flow period and the end of the high-flow period. Our method underestimated hyporheic discharge during high flow. We hypothesized that the differential discharge and mass-balance methods included lateral inflows that were not detected by the fiber optic cable buried in thalweg sediment. Increasing spatial coverage of the cable as well as automatic and continuous calculation over the reach may improve predictions during the high-flow period. Coupling groundwater inflow mapping and vertical hyporheic flow allows flow to be quantified continuously, which is of great interest for characterizing and modeling fine hyporheic processes over long periods.

Challenging Assumptions About Fracture Stimulation Placement Effectiveness Using Fiber Optic Distributed Sensing Diagnostics: Diversion, Stage Isolation and Overflushing

2015 ◽  
Author(s):  
Gustavo A. Ugueto C. ◽  
Paul T. Huckabee ◽  
Mathieu M. Molenaar
Keyword(s):  
Fiber Optics ◽  
Hydraulic Fracture ◽  
Fiber Optic ◽  
Critical Factor ◽  
Horizontal Wells ◽  
Distributed Sensing ◽  
Production Performance ◽  
Distributed Temperature Sensing ◽  
Real Time Analysis ◽  
Hydraulic Fracture Stimulation

Abstract The connection of the wellbore to the hydrocarbon resource volumes via effective fracture stimulation is a critical factor in unconventional reservoir completions. Various well construction and dynamic placement methods are used to distribute treatment volumes into targeted sections of the wellbore. This paper provides some insights into the effectiveness of hydraulic fracture stimulation process using Fiber Optics (FO): distributed acoustic sensing (DAS) and distributed temperature sensing (DTS). This paper reviews examples from multiple wells where FO has been used to gain a better understanding of three highly debated fracture stimulation distribution topics: Diversion, Stage Isolation and Overflushing. Diversion is increasingly being used as a way to improve the efficiency of hydraulic fracture stimulation distributions. The effectiveness of the diversion techniques has traditionally been judged on the basis of surface pressure response during treatment and ultimately, from production comparisons to reference wells. Unfortunately, getting clear answers from production performance takes significant time. FO allows for monitoring of the diversion process in real-time. Analysis of DAS and DTS responses is used to quantify diversion efficiency in re-directing hydraulic fracture stimulation from dominant perforation clusters to those not being stimulated. Lack of isolation between stages has frequently been observed in wells with diagnostics. There is consensus amongst the completion community that communication between stages is highly undesirable because the energy and materials of the stimulation are partially or totally misdirected from the target interval to other portions of the wellbore. The analysis of DAS and DTS not only can help determine the frequency of occurrence of communication between stages in cemented and uncemented horizontal wells but also can provide insights about the different communication paths. Fiber Optic distributed sensing in conjunction with complementary diagnostics is also being used to investigate if connections are being maintained at the end of the treatment between the newly created fracs and the wellbore. The use of integrated diagnostics allows evaluation of the frequency in which overflushing (over-displacement) occurs in both vertical and horizontal wells and its impact on well inflow performance where production profiling data is available.

Geomechanical Template for Distributed Acoustic Sensing Strain Patterns during Hydraulic Fracturing

SPE Journal ◽  
2021 ◽  
pp. 1-12
Author(s):  
Yunhui Tan ◽  
Shugang Wang ◽  
Margaretha C. M. Rijken ◽  
Kelly Hughes ◽  
Ivan Lim Chen Ning ◽  
...  
Keyword(s):  
Finite Element ◽  
Hydraulic Fracturing ◽  
Strain Rate ◽  
Hydraulic Fracture ◽  
Strain Field ◽  
Low Frequency ◽  
Fracture Propagation ◽  
Fracture Network ◽  
Hydraulic Fractures ◽  
Distributed Acoustic Sensing

Summary Recently more distributed acoustic sensing (DAS) data have been collected during hydraulic fracturing in shale. Low-frequency DAS signals show patterns that are intuitively consistent with the understanding of the strain field around hydraulic fractures. This study uses a fracture simulator combined with a finite element solver to further understand the various patterns of the strain field caused by hydraulic fracturing. The results can serve as a “type-curve” template for the further interpretation of cross-well strain field plots. Incorporating detailed pump schedule and fracturing fluid/proppant properties, we use a hydraulic fracture simulator to generate fracture geometries, which are then passed to a finite element solver as boundary conditions for elastic-static calculation of the strain field. Because the finite element calculated strain is a tensor, it needs to be projected along the monitoring well trajectory to be comparable with the DAS strain, which is uniaxial. Moreover, the calculated strain field is transformed into a time domain using constant fracture propagation velocity. Strain rate is further derived from the simulated strain field using differentiation along the fracture propagation direction. Scenarios including a single planar hydraulic fracture, a single fracture with a discrete fracture network (DFN), and multiple planar hydraulic fractures in both vertical and horizontal directions were studied. The scenarios can be differentiated in the strain patterns on the basis of the finite element simulation results. In general, there is a tensile heart-shaped zone in front of the propagating fracture tip shown along the horizontal strain direction on both strain and strain rate plots. On the sides, there are compressional zones parallel to the fracture. The strain field projects beyond the depth where the hydraulic fracture is present. Patterns from strain rate can be used to distinguish whether the fracture is intersecting the fiber. Along the vertical direction, the transition zone depicts the upper boundary of the fracture. A complex fracture network with DFN shows a much more complex pattern compared with a single planar fracture. Multiple planar fractures show polarity reversals in horizontal fiber because of interactions between fractures. Data from the Hydraulic Fracturing Test Site 2 (HFTS2) experiment were used to validate the simulated results. The application of the study is to provide a template to better interpret hydraulic fracture characteristics using low-frequency DAS strain-monitoring data. To our understanding, there are no comprehensive templates for engineers to understand the strain signals from cross-well fiber monitoring. The results of this study will guide engineers toward better optimization of well spacing and fracturing design to minimize well interference and improve efficiency.

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