bluuebunny/crossref_metadata_2025 huggingface dataset:
NMR While Drilling in 6-in Hole - Advanced Technology as a Source-Less Solution for Well Placement Efficiency and Formation Evaluation for Reservoir Characterization in Highly Heterogeneous Carbonate Reservoir – A Case Study from Offshore Abu Dhabi
Authors: Khemissa Hocine , Ashraf Muhamed , Al-Felassi Ali , AL-Dhafari Bader , Goraya Yasser In. , Smart Charles , Bhatt Pranjal , Soliman Ahmed , Fernandes Warren , Saravanakumar Krishnan
Published: November 2017

This paper presents the successful implementation of logging-while-drilling (LWD) nuclear magnetic resonance (NMR) source-less and lithology-independent technology to place an extended horizontal drain in best porous zone of a challenging, highly heterogeneous thin layer of carbonate rocks. The technology enables this goal by providing advanced formation evaluation and characterization.

The objective was to drill a 3000-ft horizontal drain, targeting two stepped down porous units with a net thickness ranging from 6 to 9 ft, a porosity of 3 to 20 %, and a permeability range of 4 to 20 mD.

To compare NMR porosity measurement and derived density/neutron porosity in a reference well, a combined bottom hole assembly was designed with density-neutron and NMR along with resistivity and gamma ray instruments to simultaneously log the reservoir. The NMR permeability index was calibrated using parameters developed by integrating the LWD-NMR results with core/mobility data. The generated relationship was then applied to calculate rock properties in wells with LWD-NMR, targeting the same reservoir in this field.

The LWD-NMR porosity played an important role in real-time confirmation of well placement within the best porous zones. In addition, the instruments performed reservoir characterization such as porosity distribution (total, movable and bound) and permeability index derivation along the horizontal drain. The LWD-NMR results, porosity and calibrated permeability were used to identify reservoir flow units by applying a Modified Lorenz Plot, which resulted in identifying best producible flow units zones for well completion.

Based on a consistent correlation between the neutron density-derived porosity and the NMR measured porosity achieved in the studied wells, NMR combined with resistivity and gamma-ray was a solution for geosteering. This combination also resulted in rig-time savings, and it eliminated risks associated with drilling using radioactive sources and formation evaluation rock properties in this reservoir.

The replacement of radioactive source-based technology with the source-less LWD-NMR enabled efficient well placement and reservoir characterization for reservoir completion.
Technology Trends in Cement Job Evaluation Using Logging Tools
Authors: Khalifeh Mahmoud , Gardner Dave , Haddad Muhammad Yasser
Published: November 2017

The present article reviews the technology trends in cement job evaluation using logging tools and considers the main advantages and concerns associated with each technology. The technologies covered include recent acoustic tools, temperature logging, noise logging, resistivity logs, oxygen activation logs, X-Ray measurements, Gamma-Gamma density measurements, Neutron-Neutron logging, and fiber-optic measurements.

Technology trends in cement logging tools suggest that acoustic measurements such as pulse-echo and flexural measurements may be the leading techniques for cement job evaluation into the next decade. Although temperature logging tools are available and have potential for well integrity evaluation their application for primary cement job evaluation remains limited to top of cement location and qualitative evaluations. Various noise logging tools are commercially available to detect leaks but their application is limited to investigating well integrity issues and not primary cement job verification. Among the technologies and techniques reviewed, theoretically Neutron-Neutron and X-ray measurements may have the potential to be future technologies for cement job evaluation. Neutron-neutron logging tools have the advantage of being already available whereas X-ray logging tools are not yet developed for cement job evaluation. Besides tool availability, power supply, tool size, and data analysis are challenges to be solved when implementing an X-ray based technique.
Do You Know About Vibration In Static Equipment?
Authors: Mashjari Khoula Al , Awadhi Ibrahim Al , Sharma Ashok
Published: November 2017

High vibrations were observed in one of the largest incinerator (6m diameter and 44m long) of recently commissioned all four SRU in GASCO plant (Fig. 1) which could lead to integrity concern and increase inspection and maintenance of the unit. Some damage of refractory, insulation and nozzle weld were also observed. This paper presents state of the art analysis and approach followed to not only identify the root cause but also provide solutions to mitigate the vibration.

The high vibration posed a challenge, as unlike rotating equipment/piping, no industry standard defines acceptable vibration for static-equipment. Actual vibration measurement across complete length of the incinerator were performed for various operating condition. Operating data were analysed for these condition. In order to study the acoustic response, natural frequencies of the system and identify source of vibration, 3D models of not only burner, but incinerator, superheater, stack and air and process gas ducting was also build. Further, instead of conventional CFD, specialized thermo-acoustic CFD analysis for numerous operating cases and FE/Fatigue analysis were performed to address this complex combustion issue.

Vibration measurement concluded that even though frequency of vibration is same throughout the incinerator, high amplitude upto 38rms with 11Hz frequency is in superheater and frequency drops by a decrease in temperature. As conventional CFD analysis could not identify the source of the vibration, a specialized complex thermo-acoustic analysis was carried out. Analysis concluded that vortices are formed in burner region due to improper mixing of combustion gases which created pressure fluctuations causing vibrations at frequencies correlating with field measurements. Hence improper burner design was identified as the root cause of vibration. FEA and fatigue analysis indicated potential premature nozzle failure in superheater region. Although conventional approach of replacing complete burner with new burner and ducting would have resolved the vibration and ensured integrity, however it would have costed 4MUSD. Instead, several options to eliminate the root cause were explored and provision of choke ring inside the incinerator was identified as optimum solution ($1.2M). To "Deliver More for Less" alternate solution of installation of a stiffener-ring ($80K) in super-heater region was recommended to change the natural frequency and reduce vibration to acceptable limits.

Vibration issues in the incinerator package may not only be due to flow but can also be related to combustion. Such issues are more complex especially for such a large incinerator and difficult to resolve with a conventional approach. This specialized study not only helped to identify root cause or source of vibration but also address the same in most economical way and success of analysis is supported by proper technical analysis and justification.
Application of UBD and MPD Improved Discovery of Fractured Granitic Basement Hydrocarbon Reservoirs
Authors: Chen Peng , Wang Xi , Chen Lei
Published: November 2017

Extensive discoveries of basement hydrocarbon reservoirs have been made in many places of fractured granite and carbonate basement in the world. Important hydrocarbon findings were achieved in fractured granitic basement in Chad and Indonesia by means of UBD and MPD technologies.

The granitic basement in Chad and Indonesia featured with hydrostatic pore pressure gradient with narrow density windows and well developed fractures. The pore pressure coefficient of the basement of Chad was predicted in between 1.02-1.06, and an underbalanced drilling (UBD) technology with a micro-foam drilling fluid was used to make an attempt on reducing drilling fluid losses; the pore pressure coefficient of the basement of Indonesia was estimated to be 1.04, and an underbalanced managed pressure drilling (UB-MPD) technology with a synthetic based drilling fluid was utilized to avoid drilling fluid losses and in favor of hydrocarbon discovery.

Different drilling technologies or modes received different results although drilling in same fractured granitic basement with similar pore pressure. Losses and kicks continued almost all the time during drilling, coring and wireline logging in some wells during UBD in Chad. Losses happened as soon as the rig pump started while overflow occurred no sooner than the rig pump stopped. However, the potential problem of losses and kicks was completely controlled by utilization of UB-MPD technology in Indonesia. No losses were found during underbalanced managed pressure drilling, tripping, connection, and circulation. Nevertheless, both basement hydrocarbon reservoirs in Chad and Indonesia have been obtained important discovery. Crude oil returned to the surface during UBD in Chad and abundant natural gas produced during UB-MPD in Indonesia.

Both UBD and UB-MPD technologies are effective to gain the discovery of fractured granitic basement reservoirs. The underbalanced MPD technology, a precisely pressure controlled drilling system, is able to accurately control the annular pressure profile throughout the wellbore, therefore it could effectively achieve safe drilling in narrow density window and cut non-productive time. It is proved to be more effective and safer in drilling of fractured granitic basement.
Human Factors Engineering HFE: A Review of Human Elements that have Contributed in the Occurrence of Major Accidents in Process Industries and Total Abu Al Bukhoosh TABK Means of Engineering Effective Mitigations
Authors: Viramuthu Vijai Ananth
Published: November 2017

Major accidents happen in the process industries with relatively low frequencies coinciding with extremely severe consequences. The harm to workers and the public, resulting from a loss of company property and other assets, business interruptions, and environmental degradations are all possible outcomes of such events. This paper explores the human factors in occurrence of major process accidents within the last decade and offers suggestions for their prevention via process safety management (PSM) principles, risk assessment and engineering philosophies to prevent and mitigate the occurrence of major accidents.

In the process industries, a major accident is an incident that typically results in numerous severe injuries and possible fatalities. In seeking to prevent these outcomes, a series of barriers in combination of human and engineering elements have been integrated into the process system designs. This study will review the broken human factors and barriers leading to the development of these events, while also highlighting key aspects of the Total Abu Al Bukhoosh (TABK) Technological Risk Assessment (TRA) processes. These assessments seek to ensure similar major accident hazards and threats are arrested through proper evaluation and systematic installment of human specific barriers.
Extensive Miscible Water Alternating Gas WAG Simulation Study for a Giant Offshore Oil Field
Authors: Kohata Akihiro , Willingham Thomas , Yunus Khan Mohammad , Al Sowaidi Alunood
Published: November 2017

The subject field is a giant offshore reservoir with light oil and a planned long production life extending beyond 100 years. In order to sustain oil production, EOR will be implemented at the appropriate time. As a result of EOR screening, miscible water-alternating-gas (WAG) injection was identified as one of the suitable methods. In order to evaluate miscible WAG potential, extensive WAG simulation studies were conducted in each step including 1D, 2D and 3D simulation.

First, 1D simulations were conducted for tuning the equation of state (EOS). Second, 2D conceptual model simulations were carried out for the preliminary evaluation of WAG. Then, 3D conceptual models for two typical geological areas of the subject reservoir, the "Homogeneous" and "Heterogeneous" geologic areas were generated and findings from the 2D simulation study were validated. Finally, 3D sector model simulations were conducted using the history-matched simulation model to evaluate the miscible WAG potential for full field implementation and its economics. In all simulation studies, CO2 and hydrocarbon (HC) gas were evaluated as miscible injectants.

1D simulations replicated a slimtube test and EOS parameters were tuned to match the minimum miscible pressure (MMP) of CO2 and HC gas. As a result of 2D simulations, "Tapered" WAG appears the most attractive WAG injection scheme in terms of gas utilization and oil recovery. In the Tapered WAG concept, the durations of gas injection varies where longer gas injection cycles are completed initially progressing towards shorter gas injection cycles with progressive WAG sequences. The Tapered WAG concept was also tested using the 3D conceptual model and similar findings were obtained. To evaluate miscible EOR WAG for the full field, due to the size of our field, the high resolution gridding required to capture fluid transport and the 9 component tuned EOS, the required computing resources exceed typical computing capacity; hence, two sector models which represent the Homogeneous and Heterogeneous areas were generated. Based on simulation results, normalized type curves for the hydrocarbon pore volume injected (HCPVI) with incremental recovery factor were generated for each geological area. A production and injection profile for full field WAG implementation was generated by applying these type curves to each pattern and incremental oil production was estimated.

The potential incremental oil production for WAG application for a giant offshore oil field was successfully assessed utilizing extensive simulation scenarios from a preliminary concept using simplified models to a detailed full field analysis using complex models. Through this step-by-step analysis, we were able to efficiently identify the key criteria impacting full field recovery including Tapered WAG, impact of injectant and impact of multi-scale heterogeneity (e.g. 2D-3D).
Success Through Continuous Innovation to Achieve Better Zonal Isolation in Extended Reach Wells in a UAE Field
Authors: Mahamat Habib Abdelkerim Doutoum , Al Katheeri Yousif Saleh , Seales Sheldon , Ramdeen Rayaz Evans , Bermudez Romulo Francisco , Navas Luis Eduardo , Kapoor Saurabh , Pallapothu Surya , El Hassan Azza , Jain Bipin
Published: November 2017

Achieving well integrity relies on achieving zonal isolation among narrowly separated sublayers of the reservoir throughout a long openhole section. This requires flawless primary cementation with a perfect match of optimized fluid design and placement.

In a UAE field, there are several challenges experienced while cementing production sections, predominantly due to long open holes with high deviation, use of nonaqueous fluids (NAF) for shale stability, and loss circulation issues while drilling and cementing. The need to pressure-test casing at high pressures after the cement is set and the change in downhole pressures and temperatures during well completion / production phases result in additional stresses that can further endanger the integrity of the cement. Breaking of the cement sheath would lead to sustained annular pressure and compromise the needed zonal isolation. Hence, the mechanical properties for cement systems must be thoroughly tested and tailored to withstand the downhole stresses.

A systematic approach was applied that used standard cementing best practices as a starting point and then identified the key factors in overcoming operation-specific challenges. In addition to the use of engineered trimodal slurry systems, NAF-compatible spacers, and loss-curing fibers, an advanced cement placement software was used to model prejob circulation rates, bottomhole circulating temperatures, centralizer placement, and mud removal. To enhance conventional chemistry-based mud cleaning and to significantly improve cleaning efficiency, an engineered fiber-based scrubbing additive was used in spacers with microemulsion based surfactant. Furthermore, a real-time monitoring software was used to compute and monitor equivalent circulating density (ECD) during the cementing operation and to evaluate cement placement in real time. Results of cement jobs were analyzed to define the minimum standards/criteria and then to verify the efficiency of the applied solutions.

The 9 5/8-in. casing / liners were successfully cemented using this methodological approach, and lessons learned were progressively used to improve on subsequent jobs. Advanced ultrasonic cement bond logging tools along with advanced processing and interpretation techniques facilitated making reliable, conclusive, and representative zonal isolation evaluation. The cement bond logs showed significant improvement and increased the confidence level towards well integrity.

After establishing field-specific guidelines over 2.5 years, continuous success was replicated in every well for all the rigs operating in this UAE field.
Sour Service Challenges
Authors: Bruschi Roberto , Gentile Manuela , Torselletti Enrico
Published: November 2017

Material selection for sour service is generally based on International Standards. Sometimes there are project conditions that are not properly covered, therefore additional investigations are needed. This fact can arise conflictual discussions between the lay contractor and the field operator, regarding first the selection of the laboratory, and then the method and extent of the weld qualification campaign: disagreements may impact the installation schedule as well as significantly affect the operational requirements. The subject is crucial in field development projects, in both shallow and deep waters, when performance requirements are particularly demanding. In the meantime, field experience shows failure conditions in sour service due to erroneous design choices, inaccuracies during construction, unexpectedly severer flow conditions and/or poor mechanical performance of both line pipe and welds.

Therefore, the upstream community is currently involved in joint industry initiatives that aim to establish international consensus on updating guidelines, aiming to include the lesson learnt from recent project outcomes. The challenges of sour service mainly regard material selection in case of long distance export pipelines from offshore fields, as well as the allowance of functional and environmental load effects on flowlines, i.e., the permissible number and entity of either few high stress cycles on high temperature high pressure flowlines or many small stress cycles on risers and free spans.

In this paper an outline of sour service in offshore projects will be given, with comments on the state of the art from the designer and laying contractor's viewpoint. In particular, lessons learnt from recent experiences are discussed, in relation with the efforts for standardization currently undertaken by international certification bodies.
Deepest Horizontal Well Drilled to TD Using an Underbalanced Nitrified Foam System in a Depleted Limestone Formation in Pakistan: An Analysis of the Design, Execution, and Results
Authors: Khalid Ali , Ashraf Qasim , Luqman Khurram , Takla Elie , Nabi Agha Ghulam , Ashraf Sajjad , Hasan Naveed , Ali Muhammad
Published: November 2017

Located in Sindh on the right bank of the Indus River, the Kandhkot Gas Field was discovered in 1959 and was estimated to contain up to 680 Bcf of gas reserves. The field contains three producing formations: Habib Rahi Limstone, Sui Upper Limestone, and Sui Main Limestone. The Sui Main Limestone formation has been depleted because of extensive production, and it currently exhibits a very low pressure of approximately 3.5 lb/gal (419 kg/m3) equivalent mud weight (EMW).

An operator drilling with a conventional mud system encountered total losses and resorted to heavy lost-circulation material (LCM) pills and cement plugs to cure them. All bridging materials pumped in the hole to cure losses invaded the reservoir formation. As a result, the completed well required excessive cleanup operations to bring it into production. Therefore, the operator faced costs of loss curing materials, damage to the reservoir formation, and a substantial amount of time for drilling and cleanup operations.

The operator sought a solution to not only reduce the costs associated with drilling this highly depleted reservoir formation, but also mitigate invasion damage that inevitably affects overall production volumes. Although underbalanced drilling had been used in similar situations, the operator considered the challenges of this well before execution. The horizontal well design contained a vertical section of about 1,640 ft (500 m). Challenges to account for while drilling the horizontal leg included designing appropriate directional drilling equipment for use with a multiphase fluid, cleaning the hole in the horizontal leg, maintaining underbalanced wellbore pressures in the presence of high annular pressure loss, and achieving drilling performance to offset the cost incurred by underbalanced drilling.

For the given reservoir pressure of 3.5 lb/gal (419 kg/m3) EMW, a nitrified foam system was designed to achieve an equivalent circulating density (ECD) below 3.5 lb/gal (419 kg/m3) EMW. The foam system used a specially formulated polymer system to yield a high foam quality for suspension and cutting carrying capacity. The directional drilling equipment consisted of a special mud motor and extended range electromagnetic measurement-while-drilling (MWD) system to enable drilling with a multiphase fluid system. In addition, a downhole isolation valve deployed inside the casing string enabled isolating the live well while tripping. Using the custom underbalanced system, the operator drilled the well to total depth (TD) in just 3 days and achieved an ROP average of 49 ft/hr (15 m/hr). The paper outlines the planning and design of the underbalanced drilling package, the wellsite execution, and the achieved results.
Security of Critical Infrastructure Using Marine Radar Surveillance
Authors: Johnston Brian
Published: November 2017

The protection of the critical national infrastructure involving oil, gas, water and electricity is vital for the functioning of every country's societal and economic well-being. The selection of high performance and cost effective monitoring solutions for the safety and security of both the people working on offshore platforms as well as locations of national critical importance is crucial. Marine radar surveillance systems can provide early and rapid detection and notification of marine hazards or threats. Trends in various threats to critical infrastructure, such as from terrorist and criminal activities, have created a shift towards a stronger perimeter security model with a focus on countering irregular, asymmetrical threats within a nation's coastal security zone or a localized offshore platform security zone. This has necessitated a change towards smaller, integrated surveillance platforms with associated technologies that serve multiple operational profiles. Separating cooperative targets, using technologies such as AIS, from uncooperative or unidentified targets, has become a priority for many who operate in the maritime environment.

Sensor systems that provide an enhanced 24 hour level of detection and tracking capability in littoral environments that also are cost effective and can be configured across a wide number and range of platforms and locations provide exceptional value in both performance and cost.

Rutter Technologies has developed an enhanced radar processor system, the sigma S6, which provides a superior detection and tracking capability through the implementation of scan averaging and signal processing, making it ideally suited for small patrol vessels, other enforcement platforms, commercial shipping vessels, oil & gas platform operators, and coastal/port security applications.
Identification and Modeling of Inter-Reservoir Communication Using an Integrated Multi-Disciplinary Structural Framework in a Giant Offshore Carbonate Field, UAE
Authors: Shekhar Ravi , Almazrouei Khulood A. , Wendland Corey , Obeta Chukwudi , Al Zinati Osama , Omura Taihei , Bengharbia Mourad , Al Neyadi Abdulla , Khouri Naeema , Al Shehhi Budoor Hasan
Published: November 2017

The challenges to effectively manage a field with stacked reservoirs that are in known hydraulic communication are enormous. Conventional management of such fields can result in many undesired outcomes such as premature water production caused by cross-communication from different reservoirs, inefficient pressure support to some of the individual reservoirs, or large volumes of bypassed oil. The major challenge is to identify the reasons and magnitude of inter-reservoir communication, and accurately capture these in the models which are utilized for optimized well placement and efficient field development.

This paper discusses an integrated multi-disciplinary approach to identify and model inter-reservoir communication in a giant offshore carbonate field from UAE. Tracer study conducted for several years combined with detailed seismic interpretation suggest that the cross-flow of reservoirs due to fault juxtapositions is the major cause of inter-reservoir communication. This observation is further supported by pressure-transient analysis, logs, cores, drilling reports and regional structural studies. Hence, it becomes absolutely essential to build a robust static and dynamic model that can accurately capture the communication between different reservoirs. This paper proposes a novel approach to build a full-field integrated framework that allows coupling of multiple reservoirs that have been previously modeled independently. The methodology includes; detailed reinterpretation of faults and key chronostratigraphic surfaces, qualitative/ quantitative attribute analysis using reprocessed 3D seismic (post-stack time migrated) data, interpretation of pressure transit analysis, logs, surveillance data and regional structural history studies. The updated framework ensures accurate fault throw and fault extension in order to capture fault juxtapositions.

The ability of the new model to allow inter-reservoir communication has been tested and confirmed in dynamic simulation model. This was achieved through series of simulation sensitivities where tracers injected in wells targeting specific reservoirs were successfully sampled from different reservoirs due to inter-reservoir communication through fault juxtaposition. Based on the results of sensitivity test, it is expected that the new integrated framework will provide a much improved history match in faulted areas where cross-communication across reservoir is very prominent. The improved model will lead to a better understanding of field and possibly will be used as guidance for field development plan.
Intelligent Drilling System: Expanding the Envelope of Wired Drill Pipe
Authors: Sehsah O. , Ghazzawi A. , Vie G. J. , Al-Tajar T. , Ali A. , Al-Mohammed A. H. , Itani M. , Ullah S. , Escalera H. , Balka M.
Published: November 2017

The intelligent drilling system (IDS), based on the 57,000 bits per second and bi-directional wired drill pipe telemetry, has been under experimental trial in the industry in a variety of applications. Several SPE papers have covered these applications, which include: drilling optimization, hole cleaning, drilling risks and NPT reduction. The IDS can also be utilized with other tools to expand the window of drilling optimization applications to include the risk management approach, where the system value and the impact on drilling operations will be greater.

To achieve this change, it is important to expand and improve the current techniques and develop new methods that will expand the application of the wired drill pipe (WDP) system. This paper will describe the application of WDP in middle east during a trial test, showing how it was expanded and customized to suit complex drilling environments.

This field trial involved a three-phase approach. Each of these phases tested the functionality and application of the IDS to determine the potential benefit for different projects.

Phase 1 aimed at testing the system functionality and integrity. This includes along string measurements (ASMs), logging while drilling (LWD) data transmission, wired bottomhole assembly components, top drive and surface system, and interface sub and signal boosters.

Phase 2 aimed at testing the top-of-mud measurements derived from the ASMs pressure readings. The objective was to test the algorithm and validate the results to ensure accurate readings. Measuring the fluid level is critical in managing total loss situations.

Phase 3 aimed at early kick detection simulation. In this phase, a kick was simulated by pumping a heavy mud pill and checking ASM response while the pill was progressing up the annulus. This simulation has important applications in early downhole kick detection in total loss situations where there are no returns to surface.

Finally, the paper will outline future applications of the IDS in managing risk in complex and risky drilling environments. This is where total losses are encountered while drilling across high-pressure reservoirs. Fluid level, in total losses situation, will be monitored by high-frequency downhole pressure measurments at multiple depths. These measurements of the downhole hydrostatic and dynamic pressure will also be providing early kick detection.
Novel Compositions Based on Nanomaterials Designed for Use as Conformance Sealants
Authors: Kalgaonkar Rajendra , Wagle Vikrant , Alnoaimi Khalid , Alhussain Ismail
Published: November 2017

Conformance sealants are widely used in the oil industry to prevent unwanted water production. Though a variety of chemicals are used by the industry to control water production, most of them are not accepted in the regions with strict environmental regulations.

This paper provides development of a novel plugging and sealing system for the water or gas producing zones. The newly developed conformance sealant is based on a delayed activation chemistry to gel up nanomaterial based dispersion. The nanomaterial used in this study is environmentally benign. The activator which are used in this study to gel up nano material enables the conformance pill to be precisely placed in to the target zone, before the nano material dispersion gels up thus avoiding premature plugging of pipe lines, coiled tubing or other tubulars. The newly developed system can effectively prevent water and gas flow with BHST up to 300°F. The static gelation times were evaluated at different temperatures up to 300°F. An increase in temperature causes increase in the particle collision leading to lower gelation times. The effects of concentration and particle size of activators on gelation times of the new conformance system over a range of temperatures have also been studied. We report the effect of surface charge modification of the nanomaterials on their ability to effectively seal the target zone. The effect of shear rate on geling time of the conformance sealant was also evaluated. Different activators ranging from inorganic to organic were investigated for their effect on the gelation properties of the nanomaterials. The plugging efficiency of the new system was evaluated using coreflood studies. It was shown that the gelation time of the conformace sealant can be controlled by surface charge modification as well as by adjusting the concentration of the activator, which is advantageous as it allows the sealant to remain pumpable over predictable periods of time.

The system can effectively prevent unwanted water production. It gives a predictable and controllable pumping time, ranging from a few minutes to several hours at over a wide range of temperatures. This is an important advantage of the present invention as it allows the sealant to remain pumpable for sufficient time for placement and develops the network structure that leads to gelation, over a predictable period of time. The set gel appears as a crystalline solid. It could remain homogenous and stay in place under confined conditions, such as fractures and pore spaces.

The novelty of the newly developed sealant is to have a controllable gelation time under a variety of downhole conditions to allow accurate placement without premature plugging inside the wellbore.
Sweet-Spotting and Unlocking Tight Gas Volumes of Lower Miqrat Formation
Authors: Lukmanov R. B. , Ibrahim E. G. , Shamsi K.
Published: November 2017

Miqrat is a complex clastic deep tight gas reservoir in the North of the Sultanate of Oman. The Lower unit of the Miqrat formation is feldspatic sand characterized by low permeability not exceeding 0.1 mD and porosity up to 12 %. Based on results of the appraisal campaign of Field X, it contains significant volume of gas. However the production test data after fraccing showed mixed results. The objective of this study was to explain the production behavior and identify the sweetspot area for further development.

Understanding the reason of possible overestimation of log derived Hydrocarbon saturation is important. Thus the interpretation of conventional and special logs was revisited. In parallel, all the available core data including SCAL and thin sections were scrutinized. Besides, the analysis of hydraulic fracture propagation, well tests, cement quality, PLT including Spectral Noise Log was performed. The wells were subdivided into categories according to their production results:–wells producing no water–wells with water channeling from the water leg of Middle Miqrat–wells with transition zone intervals with 2 phase inflow of water and gas.

Based on the integrated analysis, extend of the gas and transition zones was established, and the location of future wells optimized. From the Spectral Noise log and Temperature data, water crossflow/channeling from Middle Miqrat was identified in 2 wells, either because of broken thin sealing shale above Lower Miqrat or due to poor cement quality. The sweetspot area with commercial production was mapped. Substantial gas volumes have been unlocked. Besides, an explanation of the uncertainty in log derived saturation was suggested. Core plugs and thin sections revealed presence of partially filled vugs, which is not a typical case in a clastic environment. The origin of this porosity is puzzling and likely due to dissolution of early diagenetic nodules. The rock with poorly connected vugs has high resistivity even if it is water bearing. The review of capillary pressure data revealed that the transition zone could exceed 100 m. This finding is consistent with the interpretation from well tests.

The most practical implication of the current study potential of Lower Miqrat is unlocked. The integration of Open hole and cased hole logs and the additive information from Spectral Noise log for channeling/crossflow identification is shown. Presence of vuggy-like porosity in clastic sections and the impact of isolated vugs on log derived Saturation is demonstrated.
Performance Improvement: New 16-in. TCI Design Addresses Multiple Drilling Challenges Through Interbedded Shale and Carbonate Application
Authors: Beheiry Karim , Al Heiny Ahmed , Linnerud Blake , Maouche Zakaria , Al-Shelian Jasim , Muqaddas Zahraa , Al-Mekhyal Abdullah , Al-Enezi Dakhil
Published: November 2017

A 16-in. section is one of the most challenging sections to drill in southeast Kuwait. The section consists primarily of highly interbedded carbonates, anhydrites, shale, and marl intervals, with significant variations in compressive strength that range from 3 to 25 kpsi. There are potential loss of circulation zones in the Tayarat and Dammam formations, which complicates the drilling performance, required flow rate, and other drilling parameters to be controlled. Bit balling of the cutting structure was expected in some intervals where water-based mud was typically used. The drilling assembly was a pendulum rotary design for vertical wells. A positive displacement motor (PDM) assembly is typically used in directional wells.

In addition to the loss potential and long section interval, insufficient hydraulics and the high weight on bit (WOB) necessary in the Dammam to Ahmadi carbonates led to the premature failure of the cutting structure and bearings. A durable and reliable bit design was needed to drill the entire interval and the subsequent well to help reduce overall drilling costs.

Collaboration between the operator’s drilling team and the bit supplier team resulted in successfully drilling a challenging 16-in. section and multiple additional wells. Rock types, performance, and compressive strength were analyzed using an advanced software program to determine the required design changes to develop the new tungsten carbide insert (TCI) bit. The goal of the new design was to improve hydraulics configurations, create durable and robust rubber seals, and design new advanced cutting structure materials.

The new bit design provided exceptional performance in multiple wells in the 16-in. section in southeast Kuwait. The bit was used to drill three wells, with a cumulative footage of more than 9,000 ft in more than 240 drilling hours. Approximately two million revolutions were achieved with effective bearings and slight normal wear to the bit cutting structure elements. The new bit design helped to drill longer intervals and multiple wells with no risk of premature failure; it also helped to reduce drilling time and bit costs. A further test was implemented in directional drilling wells where the inclination was up to 50°.
When we Dare to Look Deeper: Drilling Downflank on Alternative Fluid-Fill and Reservoir Architecture Concepts for a Carbonate Field in the Sultanate of Oman
Authors: Ferrero M. Boya , Dhahli A. , Unal E. , Bazalgette L. , Wahabi A. , Holst M. , Doan H.
Published: November 2017

The development of thin oil rims in carbonate reservoirs requires good understanding of structural setting, reservoir architecture and transition zone saturations. Fields that have a tectonic and/or geochemical history after initial charge are likely to challenge standard assumptions of fluid distribution, contacts and saturation-depth relationships.

This paper is a case study illustrating downflank field extension opportunities in an oil rim, related to post-charge tectonics affecting fluid distribution and contacts.

The structure of this article encompasses four different aspects:begins by explaining the geological concepts that are being postulated for downflank hydrocarbon potential,proposes the alternative methodology of concept-driven analysis for log data interpretation,explains in detail the methodology applied to existing field data for reservoir architecture and fluid fill description,summarises the outcome of the appraisal well with respect to alternative concepts.

The workflows that justified the placement of appraisal wells downflank followed the philosophy of concept-driven analysis where data is used to eliminate hypothesis rather than averaged into one a-priori assumption or average fitting equations. The placement of the pilot appraisal well (at a depth interval and location where previous models predicted water-fill) has been enabled by the identification of stratigraphic rock types, regional variability of fracture intensity and the prediction of tilted contacts. The results of an appraisal well drilled in 2017 confirm the alternative concepts proposed from concept-driven analysis of legacy log data:–Flank reservoir thickness improvement due to post-deposition crestal erosion of best facies.–Fracture density reduction towards the northern flank of the dome structure.–Tilted oil contacts deepening towards the flank and related to paleo-charge.–Relatively dry oil production from deeper depth intervals with low oil saturation due to transition zone water mobility.

The drive mechanism and development options for the field should be investigated further.
Selected Best Practices for Geo-steering Jobs Opportunities to Grow and Enhance Customer Partnerships
Authors: Sitinjak Eri Sarmantua , Damiani Saverio
Published: November 2017

The objective of this paper is to summarize some good practices that must be in place to ensure that re-assigned geo-steering jobs run successfully. During recent years the amount of jobs that have been re-assigned to the BHGE from other Service Companies by the Drilling Team have increased significantly and were all executed successfully. This makes a strong statement, that re-assignment of jobs plays an important role in increasing the trust of the client to the services that are provided by BHGE. Job re-assignment typical results in optimized service and delivery not to mention the improved economics.

Developed a procedure for collecting data and documented some of the re-assigned jobs we did and found out the keys that can make the tool excel in execution. This good practice will really be needed in order to make successful re-assigned job. The re-assigned job comes in to play due to service provider’s (1) Tool failure, (2) Wellbore instability that causes stuck-pipe and lost in hole, and (3) Inability to provide back-up tool after tool failure or lost in hole. The unsuccessful service and inability to understand the wellbore problems become the most significant contribution in losing the job to another company. Some good practices in executing the re-assigned job will be summarized and concluded in order to get the idea how to provide expected service to client.

Integrated study from all aspect in drilling involving geo-steering engineer, geo-mechanic specialist, well planners, geoscientists, application engineers, workshop engineers, geologist, drilling engineer, drilling team and field engineer in location will enhance the ability to understand the situation in the hole and we will be able to provide faster decision how to execute the job successfully. Most of the re-assigned job initiated by wellbore stability issues in the hole, guide to another problem, and were not able to be recognized by the team in time. The second thing is series of tool failure and inability to provide the back-up tool in time. The last thing is the lack of service or unable to provide the service that is needed by the client. Successful execution in re-assigned job will increase the trust of the client to the tool and service, and also will become a good campaign in selling the service and make the client remember about our service quality. These findings will help service provider to learn about how to provide expected service and make a good decision while executing the re-assigned job.
Integrated Treatment and Disposal of Waste Drilling Fluid Onshore China: Laboratory Investigation and Process Design
Authors: Li Wai , Zhao Xionghu , Cai Bin , Liu Jishan , Yan Chao , Guo Wei , Zhang Jian , Jiang Jiwei , Peng Hui , Huang Danchao
Published: November 2017

The traditional methods of treating and disposing waste drilling fluid are encountering severe challenges with the tightening of environmental regulations in China. Commonly used chemical destabilization technology needs to be improved, and treating processes are required to be optimized and updated. This paper details a laboratory investigation on two waste water-based drilling fluids (a high-density drilling fluid and a reservoir drilling fluid) from the rig sites, as well as the corresponding treatment and disposal process design. The laboratory work focused on a solid-liquid separation technique on the basis of chemical flocculation and centrifugation. According to the properties of each waste drilling fluid, different flocculants were added to initiate chemical flocculation. The effects of type and concentration of flocculants as well as treating conditions (including sulfuric acid, dilution ratio, centrifugal speed and agent adding sequence) on the degree of separation were comprehensively investigated. To apply the separation technology in various fields, two integrated processes for collective and in-site treatments were designed and discussed respectively. The results showed that the correct combination of inorganic and polymeric flocculants can lead to a great degree of separation. In particular, a novel flocculant based on modified starch exhibited excellent performance. The molecular weight of polymeric flocculant substantially influences treatment efficiency, which can be explained by the combination of adsorption-bridging and sweep-flocculation mechanisms. Adding sulfuric acid to the waste drilling fluid in treatment is beneficial to solid-liquid separation due to the reduction of electrostatic repulsion between solid particles. Molecular weight of flocculant is also a crucial factor influencing the separation effectiveness and rate. For the two waste fluids studied, the optimal treating conditions were proposed. The weight fraction of separated liquid phase reached higher than 80% and the liquid content of the solid phase was lower than 30%. Detailed analysis and discussion of the advantages of this process were presented. Preliminary field practice of this technique exhibited its satisfactory performance. This highly-integrated technique based on novel chemical agents, rational design and high-efficiency equipment is helpful to deal with the increasing technical and environmental challenges. The information provided in this work offers a reference to relevant researchers, designers and engineers.
Integrating MPD into HPHT Well Planning
Authors: Cadd Michael , Steven Lewis , Graham Robert , van der Bos Fedderik , Maatschappij B. V , Leggett Craig , Stoian Emil
Published: November 2017

Managed Pressure Drilling (MPD) is an increasingly common technique in narrow margin HPHT wells. However, MPD is sometimes viewed as a 'bolt-on' technology, only added after much of the planning work has been carried out and all other alternatives have been exhausted. By this stage key aspects of the well design are already fixed and major benefits of MPD can therefore be missed. The decision to use MPD should be made at the earliest stage of well planning, not on the basis of having no remaining alternatives, but by understanding the value that MPD can bring to the project. By doing this, MPD can be fully integrated into the well design, rig specification, procedures and training. This paper describes how an early commitment to integrate MPD into an HPHT drilling operation can make MPD more than just an enabling tool, and turn it into a performance tool that offers significant operational benefits.