Design of a Pressure Transient Campaign for a Giant Middle Eastern Field

Imperial Users onl

Permanently-Installed Distributed Pressure Sensors for Downhole Applications

Technology advancements (e.g., hydraulic fracturing and horizontal drilling) to recover unconventional oil and gas (UOG) resources are critical in maintaining future U.S. oil and gas production levels. Permanently installed distributed downhole pressure sensors could monitor fracture propagation, assess the effectiveness of hydraulic fracturing, and optimize hydraulic fracturing placement so that overall UOG recovery efficiency can be increased. However, the harsh environment (high temperatures, high pressures, strong vibration, and presence of brine, mud, debris, hydrate, and various gases), the long data telemetry distance, and the requirements of reliability and service lifetime make the downhole monitoring a very challenging task. To combat these challenges, this thesis presents three sensing systems for downhole pressure monitoring. First, A microwave-photonic low-coherence interferometry (MPLCI) system is proposed for optical fiber based distributed sensing. The system can be used to interrogate the intrinsic Fabry–Pérot interferometers (IFPIs) based distributed downhole pressure sensors. Assisted by an unbalanced Michelson interferometer (MI), a low-coherence laser source is used to interrogate IFPIs along with an optical fiber for a dark zone-free (or spatially continuous) distributed measurement. By combining the advantages of microwaves and photonics, the MPLCI system can synergistically achieve high sensitivity and high spatial resolution. Second, to solve the packaging and drift problems in optical fiber sensors, an all-digital sensing method based on an electrical encoder is developed for downhole pressure monitoring. The key innovation of the all-digital sensor concept is the built-in nonelectric analog-to-digital converter (ADC), which eliminates the need for downhole electronics for signal conditioning and telemetry in conventional electrical downhole sensors. As such, the sensors are more robust, less expensive, and have less drift in comparison with the existing sensors. Because the sensor outputs are digital in nature, the developed sensors can be remotely logged over a long distance, and many sensors can be digitally multiplexed for distributed sensing using a single surface instrument. The all-digital pressure sensors and their surface instrument were designed, engineered, fabricated, and calibrated. The integrated sensing system was tested/validated at both laboratory and research wellbores. Third, to solve the hysteresis problem induced by the electrical encoder, a non-contact optical encoder based all-digital pressure sensor for downhole applications is proposed. The proposed sensor combines the advantages of both optical fiber and all-digital sensing method. The noncontact-type encoder, which is composed of an encoding pad and an all-glass optical fiber sensing head. A glass additive and subtractive manufacturing (ASM) system was used to embed the multi-channel optical fibers into a bulk-fused silica glass substrate with high positioning accuracy and good thermal stability even at elevated temperatures. The optical fiber only serves as the telemetry channel to directly transmit the data in digital format, such that the system has long-distance telemetry capability as well as low drift. The proposed pressure sensor was manufactured and experimentally verified to have a high SNR, linear pressure response, and good long-term stability. In addition, a mathematical model to study the relationships between the sensor’s performances and design parameters was established

Next generation intelligent completions for multi-stacked brownfield in Malaysia

Multi-stacked brownfield in Malaysia is known to have zonal contrast reservoir pressure and water cut. Commingled production without any flow control such as conventional on-off sliding sleeve will induce cross flow of production from a high pressure reservoir to lower pressure reservoir which disables optimum oil production. Having high zonal water cut contrast will cause early or excessive water production translates to deferred oil production. To pro-actively prevent these occurrences, adaptation of intelligent completion components such as Permanent Downhole Gauge (PDG) and surface-controlled Flow Control Valve (FCV) can be used. Downhole FCV choke is designed to cater for the dynamic changes of reservoir properties predicted over well life. In order to standardize the FCV choke sizing by well or by campaign, the choke sizing will be averaged to fit for all layers which is not the ultimate optimized design for maximum oil production. Latest in market today, electrical driven infinite position FCV is the solution to conventional hydraulic actuated FCV. Having infinite position enables optimized choke sizing for all reservoir layers and flexible to tackle uncertainties and dynamic changes of reservoir properties over time which enables the ultimate optimum oil production and water cut reduction. Besides choke sizing, deployment method and operating method also contribute to installation and operating efficiency. Conventional multi-position FCVs in market today are either fully hydraulic operated or electro-hydraulic operated which require hydraulic pump units at surface to enable pressuring up hydraulic control lines to change the position of FCV. It is also time consuming during deployment due to the requirement of electrical splicing, hydraulic splicing and FCV actuation sequence. Infinite position FCV is electrically operated using single downhole cable that can be multi-dropped to more than 25 FCV which reduces deployment time. With WellWatcher Advisor software that provides real time optimization features, operating efficiency is improved significantly with infinite position FCV as compared to conventional multi-position FCV and on-off sliding sleeve

Novel methods for active reservoir monitoring and flow rate allocation of intelligent wells

The value added by intelligent wells (I-wells) derives from real-time, reservoir and production performance monitoring together with zonal, downhole flow control. Unfortunately, downhole sensors that can directly measure the zonal flow rates and phase cuts required for optimal control of the well’s producing zones are not normally installed. Instead, the zonal, Multi-phase Flow Rates (MPFRs) are calculated from indirect measurements (e.g. from zonal pressures, temperatures and the total well flow rate), an approach known as soft-sensing. To-date all published techniques for zonal flow rate allocation in multi-zone I-wells are “passive” in that they calculate the required parameters to estimate MPFRs for a fixed given configuration of the completion. These techniques are subject to model error, but also to errors stemming from measurement noise when there is insufficient data duplication for accurate parameter estimation. This thesis describes an “active” soft-sensing technique consisting of two sequential optimisation steps. First step calculates MPFRs while the second one uses a direct search method based on Deformed Configurations to optimise the sequence of Interval Control Valve positions during a routine multi-rate test in an I-well. This novel approach maximises the accuracy of the calculated reservoir properties and MPFRs. Four “active monitoring” levels are discussed. Each one uses a particular combination of available indirect measurements from well performance monitoring systems. Level one is the simplest, requiring a minimal amount of well data. The higher levels require more data; but provide, in return, a greater understanding of produced fluids volumes and the reservoir’s properties at both a well and a zonal level. Such estimation of the reservoir parameters and MPFRs in I-wells is essential for effective well control strategies to optimise the production volumes. An integrated, control and monitoring (ICM) workflow is proposed which employs the active soft-sensing algorithm modified to maximise I-well oil production via real-time zonal production control based on estimates of zonal reservoir properties and their updates. Analysis of convergence rate of ICM workflow to optimise different objective functions shows that very accurate zonal properties are not required to optimise the oil production. The proposed reservoir monitoring and MPFR allocation workflow may also be used for designing in-well monitoring systems i.e. to predict which combination of sensors along with their measurement quality is required for effective well and reservoir monitoring

Brodgar Downhole Gauge Analysis with Deconvolution

Imperial Users onl

Development and evaluation of a coaxial cable sensing system for CO₂ sequestration wellbore integrity monitoring

Downhole monitoring plays a crucial part in geological carbon dioxide (2) sequestration. Various downhole monitoring technologies have been explored and applied, but they are either expensive or have system longevity issues. To address this issue, a robust and cost-effective downhole sensing system based on distributed coaxial cable sensors is developed and evaluated in laboratory, and a numerical simulation with staged finite element model is conducted to study the feasibility of using the coaxial cable sensing system for monitoring and evaluation of wellbore stability during CO2 injection. The real-time distributed sensing system is composed of Fabry-Perot interferometer based coaxial cable temperature and strain sensors. A high pressure high temperature (HPHT) sensor testing system is developed to study the temperature sensor accuracy, sensitivity, stability, hysteresis, and crosstalk effect under simulated downhole conditions. A lab-scale prototype of the casing imager based on strain sensors is developed and tested in laboratory to prove its real-time monitoring ability in casing axial compression, radial expansion, bending, and ovalization. A parametric study with staged finite element analysis is conducted to study the feasibility of using the casing imager in wellbore stability monitoring and evaluation during CO2 injection in the Weyburn field. The system is proved to perform under 1,000 psiaand 110 ⁰C, with real-time monitoring ability in casing axial compression, radial expansion, bending, and ovalization. And the parametric study with finite element model not only proved the feasibility of using the system for wellbore stability monitoring and evaluation during CO2 injection in the Weyburn field, but also provided insight into the best cementing practice and injection conditions as guidance to avoid leakage risks in a geologic CO2 sequestration project --Abstract, page i

Application of Fiber Optic Technology in Reservoir Monitoring

The purpose of this thesis was to gain an overview of fields of application of fiber optic technology in reservoir monitoring, how such a measurement system is operated, and challenges that can occur. For automated and integrated processes in the exploration and production of hydrocarbons, the information available before, during, and after operations is of great value. Where to place wells and templates, at which rate and when production and injection is to take place are just a few of the decisions in such processes. Fiber optic technology which is common in reservoir monitoring tools in a production well, is also used for seismic and monitoring of the subsurface and pipelines along the seabed. Fiber optic measurement systems are of great value thanks to real-time data, which are an advantage in decisions to be made on short notice. By implementing fiber optic sensing elements along a wellbore, from the reservoir section and up to the surface, well intervention operations, testing of downhole safety equipment, well integrity assurance, and an active reservoir management on drainage and injection strategies can be optimized and profitability maximized. With in-well fiber optics already in place, they can be used for various operations. From cementing a liner, reservoir monitoring, and fluid characterization, to measuring strain and conditions of downhole equipment. Published papers, course material and equipment from Weatherford, discussion with field specialists, and personal experience have been the basis of the thesis. It was successfully demonstrated how a bad splice affects the optical power transmitted through a fiber optic cable, that attenuation on the emitted light has a boundary, and how important a test of an entire measurement system before operations is. The installations by Equinor at the Johan Sverdrup field are a good example of benefiting from implementation of technology from the start of development. The digitalization of the green field is part of their high ambition of a 70 % recovery. Fiber optics are a great choice of measurement systems for reservoir monitoring with many sensing elements already available in today’s market, and will most likely be a preferred choice for monitoring many wells and reservoirs in the years to come

Evaluation of ceramic coaxial cable sensors for long-term in-situ monitoring of geologic CO₂ injection and storage

Monitoring is an essential component of CO₂ injection and storage projects in order to manage the injection process, identify leakage risks, provide early failure warnings, determine the movement of CO₂ plume and provide input into reservoir models. In-situ monitoring provides critical and direct data points that can be used to fulfill the above objectives. However, downhole sensors that can withstand the harsh conditions and run over decades of the project life cycle remain unavailable. A new idea of ceramic coaxial cable temperature, pressure and strain sensor has recently been put forward and the sensors are under development. A high pressure high temperature (HPHT) testing system was developed in order to characterize the novel ceramic coaxial cable sensors under combined temperature, pressure and strain conditions with water, oil, brine, CO₂ and CO₂ brine mixture. Tests were conducted on a semi-rigid coaxial cable temperature sensor under combined temperature and pressure conditions with water. Besides, a preliminary test was conducted on the ceramic coaxial cable pressure sensor model to help with the design of the sensor. The semi-rigid coaxial cable temperature sensor showed an excellent ability of recording the actual temperature of hydraulic water with a constant resolution of ± 1 ºC. The preliminary test on ceramic coaxial cable pressure sensor model decided stainless steel as the proper material for sensor jacket. --Abstract, page iii

The Mechanical Behavior of a 25Cr Super Duplex Stainless Steel at Elevated Temperature

Peer reviewedPostprin

Investigation of Batch Foamer Efficacy and Optimisation in North Sea Gas Condensate Wells

Imperial Users onl