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In this case study, high resolution temperature array data, acquired during a Drill Stem Test (DST), were able to identify and quantify flow behind the liner. Quantifying the flow rate behind the liner between the production zones was of significant value to the operator to reduce the uncertainty in the Pressure Transient Analysis (PTA).
The high resolution temperature array was deployed clamped to the outside of the Tubing Conveyed Perforating (TCP) guns, which were used to selectively perforate multiple zones. Using wireless acoustic technology the temperature data were transmitted to surface to enable real time feedback during the DST. A novel thermal heat exchange model was built that could take advantage of the high resolution temperature array data acquired during the entire test. The results of the model were compared to the real data to validate the results and provide accurate flow rate measurements of the flow behind the liner in real time during the test. A sensitivity study on the various model input parameters was also carried out to reduce the uncertainty in the thermal model, the results of which are detailed within the paper. Being able to quantify the flow behind the liner allowed the operator to adjust their PTA results and provided a more robust reservoir model.
Typical thermal models in the industry are unable to quantify flow behind the liner in this environment. A new thermal model had to be developed that could take into account the complex heat transfer processes and take advantage of the high resolution thermal array data acquired during the DST. Despite the challenging wellbore environment during the test, the high resolution temperature data were used to provide a robust zonal flow confirmation and rate allocation during the flow periods.
Whilst Distributed Temperature Systems (DTS) are gaining popularity in the oil and gas industry, typically the current technology does not provide the high resolution required to be able to quantify flow behind the casing. This new model, when combined with high resolution thermal array data, has wide ranging applications not only during the DST but also in long term completions where monitoring well integrity is a real industry challenge.
Schlumberger implemented the first instrumented platform integrating advanced measurements in real-time while perforating with plug-in gun connections. This paper presents the results obtained at field level using this technology in Ecuador and a comparison of this technology with perforating operations and techniques in terms of efficiency, reliability, and correlation between the predicted and measured dynamic events to perform a full evaluation of the perforating design process, execution and its impact in well performance
Out of more than 120 jobs performed year to date in Ecuador, the authors selected 5 wells covering operations with dynamic underbalance (simultaneous and standalone) and gas fracturing to illustrate the efficiency gains of a faster and more reliable arming system and to analyze the match between simulated and measured dynamic events (pressure and shock). Among the 5 wells, two of them achieved positive production results, and the real time measurements showed additional information in terms of: reservoir pressure, well response, and perforations cleanup during the job execution. The other three wells provided key information related to well control and pressure buildup after perforations, withal they did not provide comparatively consolidated production results.
Distributed temperature (DTS) and distributed acoustic (DAS) fibre optic sensing are now commonly used as key reservoir surveillance tools. This work shows the benefit of continuous downhole monitoring during the lifetime of a well. Fibre optic cables were permanently installed in a doublet injector/monitor well system as part of a CO2 controlled released experiment at the In-Situ Laboratory in Western Australia. During the completion and injection operations various planned and unplanned events (mud circulation, cementing, drilling, wireline logging, gas and water flows) occurred. The events were monitored from surface to reservoir with DTS and DAS fibre optic cables. The DTS was recorded continuously data starting during well completion throughout the lifetime of the wells while DAS was recorded at specific points in time, mostly associated with borehole time-lapse seismic acquisitions.
For the well completion stage, the interpretation of the DTS dataset acquired during mud circulation provided information about thief zones above the reservoir. During cementing and cement hydration, DTS highlighted areas of large breakouts and confirmed cement in-fill in those intervals. During the drilling of an unexpected cement infill, it provided a unique insight into downhole progression of the drill bit.
During the CO2 injection stage, DTS enabled monitoring the phase behaviour at the injector using distributed temperature data combined with a permanent pressure downhole gauge. At the monitoring well, the injected gas breakthrough was clearly detected at reservoir level within 1.5 day after the start of injection. Moreover, the accumulation of the CO2 over time was captured accurately at reservoir level for a further 3 days. During an unexpected leak in the casing, gas from the reservoir started entering the monitoring well leading to cyclic release of water and gas at the surface. The DAS dataset enabled to pin-point the exact moment the casing leak occurred while the DTS dataset captured the cyclic nature of water and gas leakage. The sensitivity of the tools and interpretation methods are such that the downhole location of the event can be determined within 1 m and the timing within a few seconds. More importantly, the continuous and distributed recording allowed monitoring the events developing in time over the full length of the well.
This work highlights the unique benefit of permanent distributed monitoring using distributed fibre optic sensing during the lifetime of a well. The continuous and distributed recording allowed monitoring events developing in time over the full length of the well and provides direct observations for the different events while providing near-real-time information about downhole processes.
Lazreq, Nabila (ADNOC HQ) | Akl, Osama (ADNOC HQ) | Kumar, Rakesh (ADNOC Onshore) | Deminova, Anna (ADNOC HQ) | Vantala, Aurifullah (ADNOC HQ) | Al Kalbani, Muhannad (Schlumberger) | Luo, Yin (Schlumberger) | Cig, Koksal (Schlumberger) | Khan, Safdar (Schlumberger) | Cherian, Jobin (Schlumberger) | Assagaf, Mohammed (Schlumberger)
Production of shallow gas has presented a unique opportunity to implement a fit for purpose fracturing workflow due to the level of complexity these reservoirs present. Initially acquired logging data including open hole logs, mud logs, wireline pressure measurements and reservoir sampling as well as micro-frac readings confirmed the presence of relatively shallow gas in low permeability rock. Hence introducing fracturing as a favourable method of extraction made it imperative to address the level of complexity within the reservoir, which varied from the presence of anhydrites, extreme heterogeneity, water sensitivity, as well as the fault environment at such shallow depths.
Exploring pilot holes and running advanced image logs as well as acoustic measurements along with micro-frac operation, provided critical data for completion design improvement to not only enhance the chances of successful placement, but also increase the overall gas output.
The relatively low bottom hole static temperature and pressure, soft rock, heterogeneity and overall immaturity of the reservoir required extensive core flow tests. X-Ray Diffraction (XRD) as well as lithology scanner logs were also used to fully understand the complex mineralogy. A suitable salt tolerant fluid was proposed for fracturing before optimisation as well as the inclusion of fit for purpose acid systems.
The workflow also utilised the extensive geomechanical datasets for analyses, as well as incorporating the geological and petrophysical interpretations. This was followed by sensitivity analyses of the fracturing design based on size of stages, stage spacing, cluster spacing, as well as the cement quality. After performing micro-fracturing tests, a one dimensional mechanical earth model (1D MEM) was optimised to enable better understanding the fracture geometry. The workflow also included the use of chemical tracers to qualify the success of each fracturing stage within the target horizontal section.
The workflow started with a collaboration between geology, geomechanics, petrophysics, reservoir, as well as stimulation domains, which resulted in the completion of the first horizontal multistage fracturing completion within the targeted shallow gas reservoir. This milestone provided insight into the required planning for future gas wells within the region and has left significant potential for optimisation given the complexity of the reservoir.
The consolidation of a workflow to deliver the first shallow gas project in order to extract the initially confirmed gas presence has presented a novel approach to such a niche project. This was initiated by utilising a time-lapse image analysis, petrophysical and reservoir evaluation, and then coupled with the introducing propped fracturing and matrix acidizing to further calibrate log-deduced parameters. A high level of detail in core analysis, as well as micro-fracturing interpretations, have reduced the uncertainty regarding fracture generation, initiation, and fracture extension into the far field in such a shallow and unconsolidated, low temperature and pressure reservoir.
The article aims at demonstrating that distributed temperature sensing (DTS) using telecommunication cable laid along a pipeline can detect the early signs of erosion. It shows that the technique not only applies to both hydraulic and aeolian erosion, it also allows the localization of the event and the estimation of its severity.
The article introduces the physical principle behind the proposed detection solution. It reviews the heat propagation theory that sustains the approach for any water saturation conditions and soil type. It describes distributed temperature sensing capability and its uniqueness to measure and locate temperature events with meter accuracy. The technique is then validated by analyzing temperature data collected along a Natural Gas Transport System instrumented with DTS. These observations are compared with periodic surveys conducted by the operator integrity team.
FO based geotechnical monitoring is successfully used in operation to detect landslides along the Sierra section of the Peru LNG pipeline since 2010. These natural hazards are not the only ones threatening the pipeline. First, in the Sierra region, it is common to observe severe hydraulic erosion during the rainy season. Second, the coastal section, which is a desert, experiences other phenomenon such as sand dune migration and eolian erosion that put the pipeline at risk. DTS instrumentation measures continuously and automatically the fiber optic communication cable. The analysis of the monitoring data in both regions shows the detection of very localized events. Their spatial and temporal signatures are analyzed. The comparison of these data with thermal models identified sections that are near to be exposed or whose soil cover is less than 50cm over a spatial extension that does not exceed a couple of meters. Depth of cover of 10 to 30cm are estimated from such analysis. These results are confirmed by past and ongoing site inspections.
The successful detection and localization of hydraulic and aeolian erosions and confirm the value of DTS to mitigate geohazard risks. It not only enhances the efficiency of the integrity program detecting and localizing threats, it also improves and rationalizes the maintenance activities as focused surveys can be conducted.
Nowadays wells are drilled deeper, hotter, and subjected to higher downhole pressures making it more complex for completion, deployment of production tools, and to maintain long term well integrity. It is evident that the utilization of downhole data is becoming more important, to optimize production, maximize the recoverable reserves, and to preserve the proper structure of the wells, facilitating their full life cycle until decommissioning. The Energy industry is relying on new technologies to reduce the cost of exploration, production, and maintaining the wellbore's structural integrity for the duration of the well-life as well as the reduction of their decommissioning cost.
This paper addresses various new opportunities created by an "integrated" casing/tubing/microsensor technology, and real-time data communication from downhole to the surface. This manuscript will highlight some of the main components of this Novel Autonomous and Wireless Real-time Integrated Monitoring System, which consists of: A smart casing-collar module with an array of various sensors, to monitor casing/cement for the initial state of stress, formation creeping, open annuli and near-wellbore reservoir properties. This information is processed through a short-hop, two-way wireless communication system, for data and command transfer from the casing module to the tubing module, and a wireless power transfer system, to provide power from the tubing-module to the casing-module. An intelligent tubing module deployed near the smart casing-collar module that contains another set of smart sensors for production and annulus monitoring. Interfacing with the casing module is done via the short-hop wireless power transfer and communications system. Included here is a downhole power generator and a real-time wireless communication for data transfer to surface. This provides the end user, the ability of in-situ power generation and real-time wireless data.
A smart casing-collar module with an array of various sensors, to monitor casing/cement for the initial state of stress, formation creeping, open annuli and near-wellbore reservoir properties. This information is processed through a short-hop, two-way wireless communication system, for data and command transfer from the casing module to the tubing module, and a wireless power transfer system, to provide power from the tubing-module to the casing-module.
An intelligent tubing module deployed near the smart casing-collar module that contains another set of smart sensors for production and annulus monitoring. Interfacing with the casing module is done via the short-hop wireless power transfer and communications system. Included here is a downhole power generator and a real-time wireless communication for data transfer to surface. This provides the end user, the ability of in-situ power generation and real-time wireless data.
The abovementioned integrated system is aimed at addressing the entire well-life planning needs, as it can feed the asset management system for production optimization, zonal isolation, P&A placement, casing integrity, formation creeping, reservoir evaluation, and potential decommissioning requirements. Custom-specified systems can quickly adapt and incrporate new features that are of potential benefit to other "industries".
In recent years, the upstream oil and gas industry has witnessed significant breakthroughs in developing and deploying permanent, on-demand, and distributed temperature (DTS) and acoustic (DAS) fiber-optic monitoring systems to optimize well completions and enhance production. Beyond steady advances in hardware, challenges associated with the analysis of distributed optical data are being addressed to enable delivery of value-driven answer solutions and services. Such solutions are often nontrivial and must be driven by scientific workflows in which data-driven models, advanced analytics and most importantly, physics-based models are applied at the right scale to correlate the data to downhole events.
In this study, we present a methodology for integrating state-of-the-art intelligent completion and production tools together with a robust modeling and analytics framework for the efficient development of data interpretation services for complex downhole environments. The answer product platform discussed is built on fast computational models, robust data-driven analytics, cloud-based data streaming and management services, and real-time reporting delivery systems. Several case-studies demonstrate how our fiber-optics solutions and analysis are leveraged for applications such as leak detection, fluid injection profiling, acid placement, sand detection, and water ingress. For each case-history, we discuss the operational workflow for the downhole intelligent assembly, procedures for acquiring high-resolution DTS/DAS data, and the use of advanced fast physics or data driven models used to deliver the solution. Some of the application examples (e.g. water ingress and sand detection) also demonstrate how simultaneous measurements of DTS and DAS data are often critical to detecting and devising a strategy for mitigating well-specific issues.
The case-studies presented in this study demonstrate how vast amounts of data can be acquired by fiber-optic interrogation systems and subsequently interpreted in real-time, or near real-time. Such a process is enabling oil and gas operators to make data-driven decisions that drive optimized reservoir performance and proactively mitigate operational risk such as NPT due to equipment failure.
Decisions in E&P ventures are affected by Bias, Blindness, and Illusions (BBI) which permeate our analyses, interpretations and decisions. This one-day course examines the influence of these cognitive pitfalls and presents techniques that can be used to mitigate their impact. Bias refers to errors in thinking whereby interpretations and judgments are drawn in an illogical fashion. Blindness is the condition where we fail to see an unexpected event in plain sight. Illusions refer to misleading beliefs based on a false impression of reality. All three can lead to poor decisions regarding which work to undertake, what issues to focus on, and whether to forge ahead or walk away from a project. Strategic thinking and planning are key elements in an organisation’s journey to maximise value to shareholders, customers, and employees. Through this workshop, attendees will go through the different processes involved in strategic planning including the elements of organisational SWOT, business scenario and options development, elaboration of strategic options and communication to stakeholders. Examples are provided including corporate, business unit and department case studies. This seminar will teach participants how to identify, evaluate, and quantify risk and uncertainty in everyday oil and gas economic situations. It reviews the development of pragmatic tools, methods, and understandings for professionals that are applicable to companies of all sizes. The seminar also briefly reviews statistics, the relationship between risk and return, and hedging and future markets.
Learn more about training courses being offered. Learn more about training courses being offered. This course covers the fundamental principles concerning how hydraulic fracturing treatments can be used to stimulate oil and gas wells. It includes discussions on how to select wells for stimulation, what controls fracture propagation, fracture width, etc., how to develop data sets, and how to calculate fracture dimensions. The course also covers information concerning fracturing fluids, propping agents, and how to design and pump successful fracturing treatments. Learn more about training courses being offered. Current and future SPE Section and Student Chapter leaders are invited to engage and share.
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