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Collaborating Authors
Pressure Management
Use Of Fiber Materials to Mitigate Lost Circulation During Cementing Operations in Turkmenistan
Bugrayev, Amanmammet (Schlumberger) | Nafikova, Svetlana (Schlumberger) | Taoutaou, Salim (Schlumberger) | Gurbanov, Guvanch (Schlumberger) | Hanov, Maksatmyrat (Schlumberger) | Rathod, Vishal (Dragon Oil)
Abstract Lost circulation in depleted sands during a primary cementing job is a serious problem in Turkmenistan. The uncertainty in formation pressure across these sands increases the risk of losses during drilling and cementing, which results in remedial operations and nonproductive time. The need to find a fit-for-purpose lost circulation solution becomes even more critical in an environment with narrow pore pressure-to-fracture gradient, where each cement job with losses compromises the downhole well integrity. An engineered lost circulation solution using innovative materials in the cement slurry was carefully assessed and qualified in the laboratory for each case to optimize the formulation. The lost circulation control treatment combines specialized engineered fibers with sized bridging materials to increase the effectiveness of treatment, formulated and added to the cement slurries based on the slurry solids volume fraction (SVF). Cement slurries with low SVF were treated with higher concentrations of the product and slurries with high SVF used lower concentrations. More than 50 jobs were performed with cement slurries designed at various densities and SVF up to 58% and using this advanced lost circulation material (LCM) to mitigate losses during cementing. Field experience showed positive results, where the differential pressure up to 2,800 psi was expected during cementing operation. A local database, generated based on the design and development work performed, enabled improved decision-making for selection and LCM application requirements for subsequent jobs and development of a lost circulation strategy. The mitigation plan was put in place against losses in critical sections and depleted sand formations in Turkmenistan. It assisted in meeting the cement coverage requirements on numerous occasions, improving overall the integrity of the wells and thus, was considered to be a success. This paper provides insight of this advanced LCM, its application in cement slurries, the logic behind the developed loss circulation strategy, and the high success rate of its implementation. Three case histories are presented to demonstrate the strategy and results.
- Asia > Turkmenistan (0.82)
- North America > United States (0.68)
- Well Drilling > Pressure Management > Well control (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid management & disposal (1.00)
- Well Drilling > Casing and Cementing > Cement formulation (chemistry, properties) (1.00)
Abstract The critical components of Managed Pressure Drilling (MPD) operations include surface manifold, surface chokes and the pipes connected to Mud Gas separators. The MPD surface equipment needs to safely handle a multiphase mixture of drilling mud, cuttings load and reservoir fluid influx during operations. The focus of this work is to establish safe cuttings load limit that can be handled by MPD system using advanced computational fluid dynamics (CFD) modeling approach. In MPD operations the surface choke is the key surface manifold component through which the fluid and cuttings flow before entering the Coriolis meter. Based on choke position only a certain volume and size of cuttings (cuttings load) can pass through chokes without causing unintentional pressure surges. In this work, Non-Newtonian fluid flow using Eulerian-Granular modeling approach is presented to understand the effects of cuttings load and different choke positions on the overall pressure drop through MPD surface manifold. Several CFD studies were conducted for different choke sizes, cuttings load and fluid properties to understand velocity profiles, cuttings accumulation and pressure drop across the MPD surface manifold. CFD results were first validated with available test data to generate confidence in CFD simulation model settings, good match was observed in pressure values between test and numerical results. Based on CFD simulations, charts were developed showing effect of operational parameters that help field personnel design the best surface equipment configuration, determine associated pressure drop and guard against the possibility of Non-Productive Time (NPT). CFD studies provided insights into cuttings accumulation and associated pressure drop change across choke for given operating conditions. Usage of advanced computational methods helped model the multi-phase flow with cuttings accurately and provided safe cuttings load estimation for given range of operational parameters.
- Well Drilling > Pressure Management > Managed pressure drilling (1.00)
- Well Drilling > Drilling Fluids and Materials (1.00)
Abstract Cementing is one of the sequences in the drilling operations to isolate different geological zones and provide integrity for the life of the well. As compared with oil and gas wells, geothermal wells have unique challenges for cementing operations. Robust cementing design and appropriate best practices during the cementing operations are needed to achieve cementing objectives in geothermal wells. Primary cementing in geothermal wells generally relies on a few conventional methods: long string, liner-tieback, and two-stage methods. Each has challenges for primary cementing that will be analyzed, compared, and discussed in detail. Geothermal wells pose challenges of low fracture gradients and massive lost circulation due to numerous fractures, which often lead to a need for remedial cementing jobs such as squeeze cementing and lost circulation plugs. Special considerations for remedial cementing in geothermal wells are also discussed here. Primary cement design is critical to ensure long-term integrity of a geothermal well. The cement sheath must be able to withstand pressure and temperature cycles when steam is produced and resist corrosive reservoir fluids due to the presence of H2S and CO2. Any fluid trapped within the casing-casing annulus poses a risk of casing collapse due to expansion under high temperatures encountered during the production phase. With the high heating rate of the geothermal well, temperature prediction plays an important part in cement design. Free fluid sensitivity test and centralizer selection also play an important role in avoiding mud channeling as well as preventing the development of fluid pockets. Analysis and comparison of every method is described in detail to enable readers to choose the best approach. Massive lost circulation is very common in surface and intermediate sections of geothermal wells. On numerous occasions, treatment with conventional lost-circulation material (LCM) was unable to cure the losses, resulting in the placement of multiple cement plugs. An improved lost circulation plug design and execution method are introduced to control massive losses in a geothermal environment. In addition, the paper will present operational best practices and lessons learned from the authors’ experience with cementing in geothermal wells in Indonesia. Geothermal wells can be constructed in different ways by different operators. In light of this, an analysis of different cementing approaches has been conducted to ensure robust cement design and a fit-for-purpose cementing method. This paper will discuss the cementing design, equipment, recommendations, and best available practices for excellence in operational execution to achieve optimal long-life zonal isolation for a geothermal well.
- Asia (0.49)
- North America > United States (0.46)
- Well Drilling > Pressure Management (1.00)
- Well Drilling > Drilling Fluids and Materials (1.00)
- Well Drilling > Casing and Cementing (1.00)
- Reservoir Description and Dynamics > Non-Traditional Resources > Geothermal resources (1.00)
A Spectacular Cementing Record in Myanmar Offshore Deepwater Well
Sun, Gang (COSL) | Ullah, Mohammad Solim (COSL) | Li, Yi (COSL) | Maheshwari, Mukesh (PTTEP) | Khumtong, Thirayu (PTTEP) | Xiong, Shao Chun (COSL) | Ai, Wu Chang (COSL) | Balaraman, Balasundaram (COSL) | Edward, Mic Mac (COSL) | Chen, Feng (COSL) | Yao, De Gang (COSL)
Abstract Myanmar offshore is considered to be a very promising exploration and production (E&P) location for oil and gas but poses significant challenges to drilling and cementing operations. Low temperature at sea bed delays the cement compressive strength development, High pore pressure with steep gradient and low fracture pressure created a very narrow drilling margin, presence of shallow flow in riser-less section further complicated the cementing operation, low density cement with high performance is a must. With the exorbiant cost of Deepwater drilling, much needed fit for purpose cementing technology with efficient logistic support and excellence in execution became crucial. This paper elaborates the cementing challenges at different sections of a recent deep-water well in offshore Mynamar and techniques that were planned and used to address those challenges. This paper will describe in detail the cementing method, how it fit the well situation, how the cement slurry was designed then evaluated and how the logistic support and execution were carried out, resulting in a resounding success.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.69)
- Geology > Geological Subdiscipline (0.50)
Abstract With the many challenges associated with Deepwater Drilling, Managed Pressure Drilling has proven to be a very useful tool to mitigate many hurdles. Client approached Managed Pressure Drilling technology to drill Myanmar's first MPD well on a Deepwater exploration well. The well was drilled with a Below Tension Ring-Slim Rotating Control Device (BTR-S RCD) and Automated MPD Choke System installed on semi-submersible rig, Noble Clyde Boudreaux (NCB). The paper will detail MPD objectives, application and well challenges, in conjunction with pore pressure prediction to manage the bottom hole pressure to drill to well total depth safely and efficiently. This exploration well was drilled from a water depth of 590m from a Semisubmersible rig required MPD application for its exploratory drilling due to uncertainties of drilling window which contained a sharp pressure ramp, with a history of well bore ballooning there was high potential to encounter gas in the riser. The Deepwater MPD package integrated with the rig system, offered a safer approach to overcome the challenges by enhanced influx monitoring and applying surface back pressure (SBP) to adjust bottom hole pressures as required. Additionally, modified pore pressure hunting method was incorporated to the drilling operation to allow more accurate pore pressure prediction, which was then applied to determine the required SBP in order to maintain the desired minimum overbalance while drilling ahead. The closed loop MPD circulating system allowed to divert returns from the well, through MPD flow spool into MPD distribution manifold and MPD automated choke manifold system to the shakers and rig mud gas separator (MGS). The automated MPD system allows control and adjustments of surface back pressure to control bottom hole pressure. MPD technology was applied with minimal overbalance on drilling and connections while monitoring on background gases. A refined pore pressure hunting method was introduced with manipulation of applied surface back pressure to define this exploration well pore pressure and drilling window. The applied MPD Deepwater technique proved for cost efficiency and rig days to allow two deeper casing setting depths and eliminating requirement to run contingency liners. MPD system and equipment is proving to be a requirement for Deepwater drilling for optimizing drilling efficiency. This paper will also capture detailed lesson learned from the operations as part of continuous learning for improvement on Deepwater MPD drilling.
- Well Drilling > Pressure Management > Managed pressure drilling (1.00)
- Well Drilling > Drilling Operations (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
Intelligent Pressure Control System for MPD
Song, Zhao Hui (Engineering Technology Research Institute of XDEC) | Li, Fu Qiang (Engineering Technology Research Institute of XDEC) | Xie, Deng Pan (Vertechs Oil & Gas Technology) | Zhu, John (Vertechs Oil & Gas Technology) | Zeng, Liam (Vertechs Oil & Gas Technology) | Wang, Xu Dong (Shale Gas Research Institution of Petrochina Southwest Oil & Gasfield Company)
Abstract MPD (Managed Pressure Drilling) is an important technique for challenging drilling operations especially in narrow operational windows. This paper is to introduce the IPC (Intelligent Pressure Control) system with super compact footprint, unique algorithm and IoT (Internet of Things) feature which bring operator a fresh understanding of MPD operation. IPC system is equipped with the ultra-compact MPD manifold (L11.75ft × W7.50ft × H9.08ft) with complete functionality of measurement & automatic control, benefit the operators on footprint reducing for limited field space. With the unique algorithm integrated in iPWD (Intellegent Pressure While Drilling) module, the real time downhole pressure data could be generated without any downhole PWD (Pressure While Drilling) sensor, the deviation between iPWD data and real PWD data is within 3%, which was proven in field operations. NEBULA system is an add-on feature for IPC system, using cloud and IoT technologies, it could track the equipment’s specific location, working status and parameters, providing statistical diagnosis based on data collected from field operations, which helps operators to make decisions quickly. The data uploaded to cloud could generate different reports based on end user’s requirements to analyze drilling operation challenges or difficulties. You can receive all data provided by NEBULA system on your cellphone and PC (Personal Computer) at any time anywhere. The compact design of IPC system manifold benefit the operator by minimizing the footprint in limited field space especially for offshore operations; iPWD module provides full time data during drilling operation regardless of connection or any pump off scenarios; also erases the need of PWD sensor on BHA(Bottom Hole Assembly). NEBULA system featured on IPC equipment generates different report based on real-time data received on site after cloud calculation and big data analysis, all data and report could be accessed via cellphone or PC at any time anywhere, which can be an upgraded intelligent features on conventional MPD technology.
- Well Drilling > Pressure Management > Managed pressure drilling (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
On the Influence of the Equivalent Circulent Density Fluctuations on the Development of the Wellbore Natural Fracture
Kamgue Lenwoue, Arnaud Regis (China University of Petroleum Beijing) | Deng, Jingen (China University of Petroleum Beijing) | Feng, Yongcun (China University of Petroleum Beijing) | Songwe Selabi, Naomie Beolle (Wuhan University of Science and Technology)
Abstract Wellbore instability is one of the most important causes of Non-Productive Time during drilling operations causing billions of dollars of losses every year. During the drilling stage, the Equivalent Circulent Density (ECD) is subjected to fluctuations caused by some factors such as the drill string vibrations cyclic loads. The fluctuating ECD applied on the fractured formation progressively modifies the initial parameters of the fractured formation such as its length and its width and this process finally results into wellbore instability. In this research, a poroelastic model based on a finite element method has been established to analyze the influence of the drill string vibration cyclic loads on the development of the wellbore natural fracture. The analysis was conducted with a two-dimensional plane strain model. A traction-separation law based on energy has been proposed for the Cohesive Zone Model. A nonlinear finite element software ABAQUS was utilized as the numerical simulator. The numerical results showed that the profiles of the fracture width as a function of time follow a sinusoidal behavior similar to the behavior of the drill string vibration cyclic loads profile. For different values of the Weight On Bit (WOB) and constant drill string Revolution Per Minute (RPM), an increase of the fracture width with the fracture length is observed in the near wellbore region. In the region far away the wellbore, the fracture width globally decreases with an increase of the fracture length for each fracture profile. the investigation of the effect of some drilling operational parameters on the development of the wellbore natural fracture also demonstrated that the drillstring vibration cyclic loads lead to an increase of the fracture length, fracture width, the loss circulation and the Bottom Hole Pressure. This study couples the integration of the fracture rock development with the continuous cyclic load generated by drill string vibrations. This aspect has been rarely discussed in the literature. The study indicates that the cyclic loads significantly affect the development of the wellbore natural fracture during drilling operations, and therefore has an important impact on the wellbore stability analysis.
- Asia (1.00)
- North America > United States > Texas (0.69)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.46)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Pressure Management > Well control (1.00)
- Well Drilling > Drillstring Design > Drillstring dynamics (1.00)
- (3 more...)
Abstract Drilling high pressure gas wells requires special consideration and precautions. The main goal is to analyze wellbore stability to plan drilling fluids and best drilling practices to minimize drilling risks. Ultimate objective is to provide a stable and smooth borehole environment for wireline logging runs and completion of a deep high pressure high temperature gas wells. Continuous collaboration and integration among all disciplines including Drilling, Geology, Geo-steering, Production Engineering and Reservoir Management is deemed key to a successful well.
- Geophysics > Seismic Surveying (1.00)
- Geophysics > Borehole Geophysics (1.00)
- Asia > Middle East > Saudi Arabia > Eastern Province > Al-Ahsa Governorate > Arabian Basin > Widyan Basin > Ghawar Field > Lower Fadhili Formation (0.99)
- Asia > Middle East > Saudi Arabia > Eastern Province > Al-Ahsa Governorate > Arabian Basin > Widyan Basin > Ghawar Field > Khuff D Formation (0.99)
- Asia > Middle East > Saudi Arabia > Eastern Province > Al-Ahsa Governorate > Arabian Basin > Widyan Basin > Ghawar Field > Khuff C Formation (0.99)
- (4 more...)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Pressure Management (1.00)
- Well Drilling > Drilling Operations (1.00)
- (7 more...)
A Blowout Accident Causative Model of Hydrogen Sulfide Oil and Gas Wells using DEMATEL and ISM Algorithms
Han, Chao (China University of Petroleum (East China)) | Guan, Zhichuan (China University of Petroleum (East China)) | Xu, Yuqiang (China University of Petroleum (East China)) | Hu, Huaigang (China University of Petroleum (East China)) | Wu, Desong (Sinopec Research Institute of Safety Engineering)
Abstract Blowout is one of the most serious accidents in the drilling process of hydrogen sulfide (H2S) oil and gas wells, often accompanied by the leakage of H2S and other toxic gases, which easily causes casualties and huge economic and environmental losses. Therefore, this article uses DEMATEL and ISM hybrid algorithms to establish a blowout accident-causing network model for oil and gas wells with H2S content, thus strengthening the risk management. In this model, firstly, the general causative factors of blowout accidents are extracted by accident statistics. Secondly, expert knowledge is adopted to determine the correlation matrix among factors. Thirdly, based on the DEMATEL algorithm, the degree of the relationship among the factors is analyzed. The importance degree (centrality) of each factor and its status as well as role (causality) in the accident-causing system are given. Finally, the ISM algorithm is used to classify the factors and establish an accident-causing network diagram with hierarchical relationship. The proposed model has been applied in a gas field containing H2S in East Sichuan, China. The results show that causative factors of blowout accidents can be divided into cause group and effect group according to the influence relationship among them. The cause group implies the meaning of the causative factors, and the effect group denotes the meaning of the causative factors. Hence, it would be necessary to control and pay great attention to the cause group factors beforehand. The key causative factors of blowout accidents are geological exploration technology, safety monitoring facilities and on-site safety culture, which belong to the cause group and are at the basic level of the accident-causing network diagram. This model has provided effective decision-making guidance for HSE work in gas field and reduced the incidence of blowout accidents. This model uses a combination of qualitative and quantitative methods to analyze the causes of blowout accidents, not only considering the relationships between factors and accidents, but also considering the relationships between factors and factors. As a result, it provides decision-making basis for the prevention and control of blowout accidents in H2S oil and gas wells.
- Asia > Middle East (1.00)
- North America > United States > Texas (0.95)
- Asia > China (0.89)
Abstract A 3 year, 23 well project drilled by a major operator in Nigeria was challenged to develop methodologies to optimize every aspect of drilling for a development project to reduce total project time and costs. The team of operator and service company personnel created an approach that systematically examined and challenged the efficiency of all tasks. They then developed and implemented innovative methods to save time by both analyzing repetitive, lengthy, or troublesome operations and challenging many status quo rig activities. The culture of continually challenging the causes of invisible lost time (ILT) that developed resulted in the creation of several critical performance improvement methodologies each of which are explained in detail. The multiple focus areas where process improvements were made included hole cleaning efficiencies, optimizing the ROP to deliver shortest well time from drilling out the casing shoe to landing the next casing, anti-collision practices to drill out conductors with a separation factor of less than 1.0, BHA design efficiencies for equipment standardization and faster make up and break down times, managing differential sticking risks, improving survey times, and developing best practices to side-track with a point-the-bit Rotary steerable system. Exact times were tracked to establish the required baselines and drilling optimization services were introduced to modify the drilling practices to reach the technical limit. The technical limit for ROP was achieved and best practices developed in this environment for effective hole cleaning, ease of tripping, and improved tripping speeds of the BHA at the end of every run saved 38.25 days over 15 wells. Average ROP's were improved by 48% in the 17 ½" section and 57% in the 12 ¼" section. The new anti-collision methodology saved 5 hours per well. BHA assembly and tool download efficiencies saved 11.47 days. Wellbore strengthening techniques prevented seepage losses and reduced stuck pipe events. Surveying improvements saved 11.78 days and new sidetracking practices saved 5 hours per sidetrack. Tasks that could be done in parallel to the critical path were identified and tasks on the critical path were performed more efficiently. ILT elimination in drilling processes saved a total of 96 days of rig time over an established performance baseline during this 23 well project. The operator set two records for the fastest drilled and completed conventional offshore wells in Nigerian history.
- Africa > Nigeria (1.00)
- North America > United States > Texas (0.28)