Soroush, Mohammad (RGL Reservoir Management, University of Alberta) | Roostaei, Morteza (RGL Reservoir Management) | Fattahpour, Vahidoddin (RGL Reservoir Management) | Mahmoudi, Mahdi (RGL Reservoir Management) | Keough, Daniel (Precise Downhole Services Ltd) | Cheng, Li (University of Alberta) | Moez, Kambiz (University of Alberta)
Accurate prediction of flow regime and flow profile in wellbore is among the main interests of production engineers in the quest of optimizing wellbore production and increasing reliability of downhole completion tools especially in SAGD projects. This study introduces a methodology for wellbore monitoring by detecting flow phase and flow regime. In order to develop this method, an advanced multi-phase flow injection experiment was designed and commissioned.
A flow injection setup was developed to test distributed fiber optic sensor installation under different operating conditions, including multi-phase flow (oil, brine and gas), and flow fraction scenarios. Different signal processing methods were applied to extract meaningful features and filter the noise from the raw signals. A statistical analysis was performed to assess the trend of the driven data. Then, typical SAGD models were simulated to assess the results of experimental setup for scale-up purpose and determination of local breakthrough of steam along the well.
Results showed that the Distributed Acoustic Sensing (DAS) data contains different levels of signals for each phase and flow regime. We also found that some level of uncertainties is involved in relating the flow regime and DAS information which could be resolved by improving the sensor installation procedure. In addition, the application of data-driven machine learning methods was found necessary to interpret the signal patterns. Initial results have shown that steam breakthrough along the well can be detected using real time DAS high energy/frequency signals. It can be concluded that including the DAS along with Distributed Temperature Sensing (DTS) is necessary to provide a better picture of steam conformance and SAGD wellbore monitoring. The limitations of the current experimental setup restricted further conclusions regarding the hybrid DAS and DTS application.
This paper is a part of an ongoing project to address the application of the combined DAS and DTS in SAGD projects. The ultimate goal is a downhole monitoring system to oversee the flow phase, flow regime and sand ingress in thermal application. The next phase will address the required improvements for developing a flow loop to handle high temperatures, include sand production and mimic thermal operation conditions.
Ugueto, Gustavo A. (Shell Exploration and Production) | Todea, Felix (Shell Canada Limited) | Daredia, Talib (Shell Canada Limited) | Wojtaszek, Magdalena (Shell Global Solutions International) | Huckabee, Paul T. (Shell Exploration and Production) | Reynolds, Alan (Shell Exploration and Production) | Laing, Carson (OptaSense) | Chavarria, J. Andres (OptaSense)
The use of Distributed Acoustic Sensing for Strain Fronts (DAS-SF) is gaining popularity as one of the tools to help characterize the geometries of hydraulic fracs and to assess the far-field efficiencies of stimulation operations in Unconventional Reservoirs. These strain fronts are caused by deformation of the rock during hydraulic fracture stimulation (HFS) which produces a characteristic strain signature measurable by interrogating a glass fiber in wells instrumented with a fiber optic (FO) cable cemented behind casing. This DAS application was first developed by Shell and OptaSense from datasets acquired in the Groundbirch Montney in Canada. In this paper we show examples of DAS-SF in wells stimulated for a variety of completion systems: plug-and-perforating (PnP), open hole packer sleeves (OHPS), as well as, data from a well completed via both ball-activated cemented single point entry sleeves (Ba-cSPES) and coil-tubing activated cemented single point entry sleeves (CTa-cSPES). By measuring the strain fronts during stimulation from nearby offset wells, it was observed that most stimulated stages produced far-field strain gradient responses in the monitor well. When mapped in space, the strain responses were found to agree with and confirm the dominant planar fracture geometry proposed for the Montney, with hydraulic fractures propagating in a direction perpendicular to the minimum stress. However; several unexpected and inconsistent off-azimuth events were also observed during the offset well stimulations in which the strain fronts were detected at locations already stimulated by previous stages. Through further integration and the analysis of multiple data sources, it was discovered that these strain events corresponded with stage isolation defects in the stimulated well, leading to "re-stimulation" of prior fracs and inefficient resource development. The strain front monitoring in the Montney has provided greater confidence in the planar fracture geometry hypothesis for this formation. The high resolution frac geometry information provided by DAS-SF away from the wellbore in the far-field has also enabled us to improve stage offsetting and well azimuth strategies. In addition, identifying the re-stimulation and loss of resource access that occurs with poor stage isolation also shows opportunities for improvement in future completion programs. This in turn, should allow us to optimize operational decisions to more effectively access the intended resource volumes. These datasets show how monitoring high-resolution deformation via FO combined with the integration of other data can provide high confidence insights about stimulation efficiency, frac geometry and well construction defects not available via other means.
Fiber optic technology has been used in several wells at an oilfield to measure strain to monitor overburden deformation. The application of this technology involved a series of bench tests and field tests to gather some key learnings to enhance well design, well construction, and fiber optic operation. Prior to installation of the fiber optic, a series of bench tests were conducted to evaluate the coupling of fiber with the capillary lines to determine its impact on the measurement of strain. The testing demonstrated that anchoring the fiber at the top and bottom of the capillary line was sufficient to hold the fiber in place and enabled the effective measurement of strain along the length of the well, which was proven when applied to field conditions. To enhance well design for strain measurement, several wells had fiber optic capillary lines installed on the inside and outside of casing to investigate the potential dampening effect due to fiber being located inside a string of casing. This was used to determine the optimal casing string to install fiber optic to measure strain in the overburden. Additionally, a novel concept was utilized in the well design that involved using the fiber optic capillary clamps as borehole centralizers, which resulted in equipment and rig cost savings. The details of the bench tests, well design, operational experience, and their associated lessons learned are presented.
Ghazali, Ahmad Riza (PETRONAS) | Abdul Rahim, M. Faizal (PETRONAS) | Mad Zahir, M. Hafizal (PETRONAS) | Muhammad, M. Daniel Davis (PETRONAS) | Mohammad, M. Afzan (PETRONAS) | A. Aziz, Khairul Mustaqim (PETRONAS)
The key objectives were to achieve better seismic resolution and spatial delineation in very heterogeneous reservoirs. We decided to supplement simultaneously the surface 3D multi component seismic acquisition by placing additional fiber optic live receivers in the subsurface via a "True-3D" experiment without shutting down the oil production. The most cost-effective method to snapshot this wavefield propagation downhole is by utilizing fiber optic Distributed Acoustic Sensing (DAS). The borehole 3D VSP data were acquired by sharing the surface OBN nodal survey airgun sources. This is an important experiment for the field in the future so that the need to halt insitu field production for 4D time lapse monitoring will not be required if the S/N is acceptable by using this method. This permanent installation of fiber optic cables has become our ears on wells, not only for 3D DAS VSP but for proactive monitoring of the field, ensuring optimum production performance throughout the life of the field.
Binder, Gary (Colorado School of Mines) | Titov, Aleksei (Colorado School of Mines) | Tamayo, Diana (Colorado School of Mines) | Simmons, James (Colorado School of Mines) | Tura, Ali (Colorado School of Mines) | Byerley, Grant (Apache Corporation) | Monk, David (Apache Corporation)
In 2017, distributed acoustic sensing (DAS) technology was deployed in a horizontal well to conduct a time-lapse vertical seismic profiling (VSP) survey before and after each of 78 hydraulic fracturing stages. The goal of the survey was to more continuously monitor the evolution of stimulated rock throughout the treatment of the well. From two vibroseis source locations at the surface, time shifts of P-waves were observed along the well that decayed almost completely by the end of the treatment. A shadowing effect in the time shifts was observed that enables the height of the stimulated rock volume to be estimated. Using full wavefield modeling, the distribution of time shifts is well described by an equivalent medium model of vertical fractures that close as pressure declines due to fluid leak-off. Converted P to S waves were also observed to scatter off stimulated rock near some stages as confirmed with full wavefield modeling. The signal-to-noise ratio is a limitation of the current dataset, but recent improvements in DAS technology can enable stage-by-stage monitoring of the stimulated rock height, fracture compliance, and decay time as a well is completed.
Distributed Acoustic Sensing (DAS) has opened new possibilities for seismic monitoring of unconventional reservoirs. Using a laser interrogator to launch light pulses down a fiber optic cable, dynamic strain changes can be sampled along the cable from the phase shift of light backscattered to the interrogator (Hartog, 2017). Since the fiber optic cable can be permanently cemented outside the casing in a borehole, highly repeatable vertical seismic profiling (VSP) surveys can be acquired frequently without costly wireline geophone deployments that interfere with well treatment activities (Mateeva et al., 2017; Meek et al., 2017).
As described by Byerley et al., 2018, a unique interstage DAS VSP survey was conducted in 2017 during the stimulation of a horizontal well targeting the Wolfcamp formation in the Midland Basin, Texas. Using two vibroseis source locations offset about 1 mile from the heel and toe of the well, DAS data was acquired in the treatment well before and after each of 78 hydraulic fracturing stages. At the expense of fewer source locations, this type of acquisition allows the evolution of the stimulated rock volume (SRV) to be monitored on a stage-by-stage basis as the well is treated.
Carr, Timothy (West Virginia University) | Ghahfarokhi, Payam (West Virginia University) | Carney, BJ (Northeast Natural Energy, LLC) | Hewitt, Jay (West Virginia University) | Vargnetti, Robert (USDOE National Energy Technology Laboratory)
The Marcellus Shale Energy and Environment Laboratory (MSEEL) involves a multidisciplinary and multi-institutional team of universities companies and government research labs undertaking geologic and geomechanical evaluation, integrated completion and production monitoring, and testing completion approaches. MSEEL consists of two legacy horizontal production wells, two new logged and instrumented horizontal production wells, a cored vertical pilot bore-hole, a microseismic observation well, and surface geophysical and environmental monitoring stations. The extremely large and diverse (multiple terabyte) datasets required a custom software system for analysis and display of fiber-optic distributed acoustic sensing (DAS) and distributed temperature sensing (DTS) data that was subsequently integrated with microseismic data, core data and logs from the pilot holes and laterals. Comprehensive geomechanical and image log data integrated with the fiber-optic data across individual stages and clusters contributed to an improved understanding of the effect of stage spacing and cluster density practices across the heterogeneous unconventional reservoirs such as the Marcellus. The results significantly improved stimulation effectiveness and optimized recovery efficiency. The microseismic and fiber-optic data obtained during the hydraulic fracture simulations and subsequent DTS data acquired during production served as constraining parameters to evaluate stage and cluster efficiency on the MIP-3H and MIP-5H wells. Deformation effects related to preexisting fractures and small faults are a significant component to improve understanding of completion quality differences between stages and clusters. The distribution of this deformation and cross-flow between stages as shown by the DAS and DTS fiber-optic data during stimulation demonstrates the differences in completion efficiency among stages. The initial and evolving production efficiency over the last several years of various stages is illustrated through ongoing processing of continuous DTS. Reservoir simulation and history matching the well production data confirmed the subsurface production response to the hydraulic fractures. Engineered stages that incorporate the distribution of fracture swarms and geomechanical properties had better completion and more importantly production efficiencies. We are working to improve the modeling to understand movement within individual fracture swarms and history match at the individual stage. As part of an additional MSEEL well pad underway incorporates advanced and cost-effective technology that can provide the necessary data to improve engineering of stage and cluster design, pumping treatments and optimum spacing between laterals, and imaging of the stimulated reservoir volume in the Marcellus and other shale reservoirs.
Fiber optics can be readily introduced into wells to gather data at very low cost by using a novel, disposable deployment method called FiberLine Intervention (FLI). To date, FLI technology has been used to cost-effectively install bare optical fiber in wellbores to collect distributed sensing data, such as distributed temperature sensing (DTS) and distributed acoustic sensing (DAS). In this ‘passive’ sensing mode a variety of applications have been demonstrated, for example, cement assurance, leak detection, injection monitoring and vertical seismic profiling.
The FLI technology has now been expanded to include "active" elements which provide additional, discrete, electronic sensing functions from within the deployed probe. This capability enables the combination of single point data with distributed sensing information to provide enhanced well intelligence and assist with a wider variety of production logging applications, including evaluating well and reservoir performance and completion effectiveness.
To deploy FLI, the probe is configured on the wellhead in a small, pressure containing launcher. This releases the probe which free-falls downhole laying the fiber into the well. Following the development of "Active FLI", the probe can now be configured to house a suite of low cost, expendable electronic sensors such as a pressure gauge, a temperature sensor and a casing collar locator (CCL). The fiber transmits the digitized sensor data - in real time - to a miniature surface data acquisition system. Following completion of sensing and monitoring operations, which typically last several hours to a few days, the probe and fiber are then disposed of in the well.
The active electronic sensors collect data during the probe's descent into the well and can continue with ongoing monitoring when the tool reaches its final depth. The sensors can be deactivated on demand and the same fiber can then be utilized for distributed sensing. Alternatively, two fibers can be deployed allowing for the simultaneous collection of single-point data and ongoing distributed sensing throughout the wellbore.
Active FLI technology will be described in this paper and data from a representative field trial will be presented. The solution remains disposable, thereby resulting in a low cost, low risk and minimal impact method for obtaining key wellbore information during shut in, production and injection operations.
Distributed acoustic sensing (DAS) is a rapidly evolving fiber optic technology for monitoring cement curing, perforation performance, stimulation efficiency, and production flow and, more recently, for performing vertical seismic profiling (VSP). VSP data can be acquired and processed to determine velocity models that are used in surface seismic imaging for reservoir characterization, or for microseismic monitoring of hydraulic fracturing operations. The limitation of conventional VSP data acquisition has been well accessibility, with wireline-conveyed tools deployed during openhole or casedhole logging campaigns before well completion or during workovers. Fiber optic cable conveyance by coiled tubing (CT) expands the opportunity for VSP data acquisition during planned CT interventions. This paper presents an example of a CT DAS VSP acquisition. The processing steps are shown to overcome some of the noise challenges inherent in CT DAS data, such as persistently strong borehole tube waves induced from the surface operations activities. A case study is shown for the depth tie between surface seismic data and the CT DAS VSP derived corridor stack image, demonstrating the viability of CT deployed fiber to acquire DAS VSP data.
Smith, Robert (Geophysics Technology, EXPEC Advanced Research Center, Saudi Aramco) | Bakulin, Andrey (Geophysics Technology, EXPEC Advanced Research Center, Saudi Aramco) | Silvestrov, Ilya (Geophysics Technology, EXPEC Advanced Research Center, Saudi Aramco)
Accurate near-surface velocity models are required to correct for shallow velocity heterogeneities that can otherwise lead to the misinterpretation of seismic data, particularly in the case of low-relief structures. Here we show how a novel uphole acquisition system utilizing distributed acoustic sensing (DAS) technology can be used in a number of different ways to generate near-surface models.
The novel smart DAS uphole system connects multiple shallow wells with one continuous optical fiber. The horizontal and vertical segments of the fiber allow several techniques for near-surface model building to be tested using the same system. Uphole surveys use the vertical fiber segments to make accurate, localized velocity measurements, while the directivity of the DAS fiber enables horizontal sections to be used for refraction tomography and surface-wave inversion.
The smart DAS uphole acquisition system, which enables the collection of data for deep reflection imaging and near-surface characterization simultaneously, has been successfully tested for the first time. Data acquired from ten smart DAS upholes produced excellent early arrival waveform quality for picking and subsequent velocity model building. This direct velocity measurement of the near-surface can reduce uncertainty in the seismic interpretation. In addition, replacing the shallow part of the depth velocity model with the DAS uphole model resulted in significant improvements in the final depth image from topography.
The directivity of DAS enables the recording of refracted events on horizontal fiber sections which have been picked as input to refraction tomography. This produces an alternative near-surface model that captures a larger volume of the subsurface. Ultimately, while the uphole velocity model is only suitable for removing long-wavelength components of near-surface variation, the refraction velocity model may allow for the correction of small-to-medium wavelength statics.
Yu, Gang (BGP Inc., CNPC, Zhuozhou 072751, Hebei, P. R. China) | Sun, Qizhen (School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, P. R. China) | Ai, Fan (School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, P. R. China) | Yan, Zhijun (School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, P. R. China) | Li, Hao (School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, P. R. China) | Li, Fei (BGP Inc., CNPC, Zhuozhou 072751, Hebei, P. R. China)
Distributed fiber optic sensing is increasingly recognized as a viable alternative to geophone arrays for the acquisition of borehole seismic data. The ability to acquire borehole seismic data in a borehole without the need to disrupt production also offers significant benefits to the operator. A novel fiber distributed acoustic sensor (DAS) with ultra-high sensitivity is presented. Through designing and fabricating the distributed micro-structured optical fiber (DMOF) with successive longitudinal microstructures to enhance the signal-to-noise ratio (SNR) of the backscattered light, and employing the coherent optical time domain reflectometer technique (C-OTDR), the sensing performance of acoustic signal can be greatly improved. Wide frequency band from 0.1 Hz to 45 kHz along the 500 m long sensing fiber cable with ultra-high strain resolution of 0.16 nɛ is experimentally demonstrated on the ground surface and in a borehole at an oilfield in South China.
Presentation Date: Thursday, October 18, 2018
Start Time: 8:30:00 AM
Location: 212A (Anaheim Convention Center)
Presentation Type: Oral