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Abbassi, Linda (OpenField Technology) | Tavernier, Emmanuel (OpenField Technology) | Donzier, Eric (OpenField Technology) | Gysen, Alain (ISP) | Gysen, Michel (ISP) | Chen, Chee Kong (Read Cased Hole) | Zeid, Ashraf (Eternal Energy) | Cedillo, Gerardo (BP)
Production logging in deviated wells has shown so far limited success in providing a reliable and cost-efficient method for production profiling. The reasons are numerous, but two factors are mainly responsible: conventional array production logging tools constitute very long toolstrings associated with expensive deployments, and data analysis is complex, requiring time-consuming analysis from cased-hole production logging experts. Overall, despite heavy investments made to perform downhole measurements, results are often disappointing and interpretation affected by a great deal of uncertainty.
A new instrumentation technology using microelectromechanical systems (MEMS) as well as new interpretation methods is offering new perspectives to this domain. In this paper, we describe a short and modular multiphase flow-sensor platform capable of achieving up to 10 times reduction in toolstring length compared to existing technology. Miniature pressure, temperature, optical, electrical, acoustic, microspinners, and ultrasonic Doppler sensors can be mounted independently from each other and easily interchanged to adapt the tool to address the well-specific challenges and meet the objectives of the surveillance program. By using both the sensor multiplicity made possible by hardware miniaturization, and diversity from multiple measurements, resolution and robustness is greatly improved. In addition, the use of digital power integrated into each individual sensor (smart sensor) provides calibrated data output, which highly facilitates the interpretation.
The new technology is an ultracompact array platform, with new sensors designs, whose superior measurements are enhanced by the new interpretation methods it enables.
Donovan, Glenn (Shell Exploration and Production Co.) | Kamath, Sagar (Shell Exploration and Production Co.) | Tanis, Elizabeth (Shell Exploration and Production Co.) | Abbassi, Linda (Openfield Technology) | Gysen, Alain (Interpretive Software Products)
Abstract This paper discusses the effectiveness of the third-generation (Gen3) Production Logging Tool (PLT) technology which incorporates the use of co-located digital sensors for simultaneous acquisition of flow data. Case studies are provided which demonstrate that this technology is a step-change in the application of digitalization to a down-hole sensor platform which provides the most accurate characterization of the flow condition at each depth surveyed. The resulting data allows for much improved processing which is also described. The probabilistic interpretive model used in the processing has been updated to incorporate this and future developments in PLT architecture. Planning, execution, and analysis of data for the wells is described in detail. Due to the significantly shorter configuration of Gen3 tools, safety at the wellsite is enhanced by allowing for a much-simplified surface rig-up. One well was logged in surface readout (SRO) mode while data in the other two were recorded in the downhole tool's memory for retrieval at the surface at the end of operations. This flexibility in logging modes optimizes operations by addressing the needs of the operation teams. Three Deepwater Gulf of Mexico producers logged with the Gen3 PLT are described. In each case, a clear path forward is provided for optimal management of the reservoirs through effective production management. The first generation (Gen1) of PLT provided a single discrete measurement for each sensor along the tool assembly's length, resulting in long tool assemblies and measurements taken at different points along the flow path. This approach had several drawbacks: long toolstrings, point sensors only provided a measurement at a single point in the cross-section of the flow, and measurements were not acquired simultaneously at each depth logged. The second generation (Gen2) of PLT was an improvement as sensors were arranged as an array enabling multiple measurements to be made at a single depth but were still long and not all were optimally arranged to capture data in the path of flow. The Gen3 PLT is one-tenth the length of the Gen1 versions and roughly one-third of the shortest Gen2 tools. Digitization allows for direct measurement of flow conditions and rapid interpretation of results. In multi-phase flow and deviated wells, the co-location of sensors in a spatial geometry provides the optimal information with which to create a fully accurate picture of the downhole flow.
Abstract Multi-stage hydraulic fracturing in horizontal wells is an essential stimulation technique to enhance production and economics in unconventional tight gas sands in North America. However, one of the challenges that still remains is to understand and quantify the efficiency of each perforation cluster in order to optimize completions. Operators have used various production logging technologies in an attempt to understand completion efficiency. Even then, these low rate horizontal wells with unstable flow conditions and fluid segregation provide a challenging environment for production logging, and even the use of different tools / software provides no definitive answer. Absence of direct comparison between logging tools renders it difficult to assess the suitability of a particular tool in a given downhole environment. A field trial was thus conducted to acquire and compare the log data using two very different instruments, an array based logging tool and a downhole distributed fiber optic (DFO) with distributed temperature and acoustic sensing (DTS / DAS) capability. A multiple array tool, consisting of multiple spinner and resistance arrays, was deployed downhole via tractor into a well that had been on production for approximately three months. Multiple up/down passes were made at different speeds in both lateral and vertical sections to assist with spinner calibration. Following this, a retrievable DFO system (with both DTS/DAS) was run in the same wellbore and data was collected continuously for two days. A memory temperature tool was also added to the DFO toolstring to ensure post-acquisition temperature calibration and depth correction. This paper highlights the advantages and disadvantages of both logging techniques and suggests ways to improve flow profiling in low rate horizontal wells. It also shows that overall comparison of the data from the two tools looks good, with some differences resulting from the different nature of these measurements. This paper further shows how other surveillance data including radioactive proppant and chemical tracers, open-hole logs, cement bond logs, and geomechanical data in these horizontal wells can be used to complement the production logging results and provide insights to optimize future completions.
Petrophysical Surveillance in Clair Field faces challenges due to reservoir properties, fluid properties, completion design and limited technology offers. Low porosity, low salinity reservoirs under waterflood recovery, coupled with high angle – horizontal wells completed with sand face valves limits the ability to log for saturation monitoring. The wells are packer segmented between major flow units, making it difficult to assess the inflow profile from individual units (sand bodies) and almost impossible to differentiate matrix from natural fractures contribution. The presence of heavy fluids (completion or asphaltenes) pose further challenges to conveyance and frequently affects the sensor responses. A surveillance campaign conducted in 2019 lead to significant improvement, with results that helped us better understand the reservoir and wells behaviour and change the surveillance strategy.
There were several different elements that we considered which led to successful results. Candidate selection is important for saturation monitoring. For the specific environment of the field we found that access to logging while drilling data (baseline capture cross section) is critical. This will also be considered for data acquisition in the remaining infill wells to be drilled. A different approach was taken for flow diagnostic in terms of sensors selection and data acquisition procedure. Generally, there is a limit on rig up height, hence a need for short tool-strings. Access to short tool-strings is also important in data gathering due to better sensors collocation and less flow disturbance, translating into a more representative downhole measurement. A tandem string of both new compact flow diagnostic sensors and traditional production logging sensors was deployed. The traditional sensors failed due to harsh well conditions while the compact system delivered reliable results without mechanical failures. One major achievement was the value we extracted from Doppler shift measurements, demonstrating that in this specific environment they can replace mechanical spinners. The compact flow diagnostic tool enabled us to change the acquisition program, reducing the logging time. This translates to less risk, less production deferment and less wear to sensors. A new multidetector pulsed neutron tool with surface and memory read out capabilities was deployed for first time in Clair field. The data proved useful to monitor the saturation change and to complement the flow diagnostic behind pipe. It also helped us to understand the dynamic behaviour of fracture vs matrix.
The paper will describe the new surveillance approach, the sensors response and the results impact on our field management strategy.
Zett, Adrian (BP) | Webster, Michael (BP) | Noordermeer, Alwin (BP) | Hockley, Mitchell (GE Oilfield Technology) | Lockyer, Glynn (GE Oilfield Technology) | Browne, Hugh (GE Oilfield Technology) | Donkin, Charles (GE Oilfield Technology)