bluuebunny/crossref_metadata_2025 huggingface dataset:
New Dry Thread Coating Reduces Risk and Costs
Authors: Klarner J. , Schalkhammer T. , Zacharias H. , Schaffer M. , Winkler P.
Published: November 2016

This paper describes a new developed dry coating for threaded Oil Country Tubular Goods (OCTG) premium pipe connections. An overview of the development is presented including the setup of the coating system and technical parameters. The basic structure of the coating system is described. The advantages of the coating compared to commonly used thread compounds are illustrated. Finally the operational areas of the coating system are presented. Different coating systems, their galling resistance and thermal stability were characterized employing tribological methods. The results of best-ranked coating systems were verified with make-up and break-out tests (M&B) on horizontal coupling application machines. Several dimensions and grades of OCTG premium connections were investigated regarding M&B capability under different conditions (e.g. deep temperature). Additionally the M&B capability was investigated with a vertical power tong, in order to simulate real life stabbing conditions on rig site. Parallel shortand long-term corrosion test series were performed to investigate the storage behavior. Finally tests according standard ISO 13679 were performed on threaded dry-coated specimens. An asymmetric coating system showed the best performance in surface adhesion and wear protection by several tribological tests. The M&B results of the dry-coated connections – without any additional lubricants – showed a stable behavior regarding torque turn monitoring. Premium connections coated with the new system were successfully made-up 15 times without initial and intermediate treatment. Recorded torque-turn diagrams revealed an unbelievable steady behavior after each make-up. In contrast to the standard procedure with doped threads the dry-coated connections haven’t to be cleaned and lubricated after each break-out. Thus, the use is significantly less time-consuming and a major risk of failure can be avoided. Additional the M&B tests with a vertical power tong and long pipes provide as well this steady behavior. The new coating system performs in a temperature range from -60°C to +60°C. Also the elevated temperatures according to ISO 13679 tests do not influence the behavior of the coating. ISO 13679 tests on a premium connection with applied dry thread coating were successfully performed. Short and long-term corrosion tests showed that dry-coated connections have enhanced corrosion stability than uncoated connections with storage compound. Hence long storage times before first make-up have no impact on the performance of the dry-coated pipe connections. A new ready-to-use product is introduced to the gas and oil industry. With the described new dry thread coating system no other lubricant is needed for the make-up of OCTG premium tubing and casing connections. This reduces risks and costs at the rig site due to easier handling. Additional there is also a positive environmental impact by replacing commonly used thread compounds through the new dry thread coating system.
Psyllium Husk in Water-Based Drilling Fluids: An Environmentally Friendly Viscosity and Filtration Agent
Authors: Salmachi Alireza , Talemi Pejman , Tooski Zahra Yarmohammad
Published: November 2016

Natural polymers are traditionally added to water based mud to improve rheological and filtration characteristics. Psyllium husk which is widely used in the health and food industries is produced from seeds of a plant which is grown and produced commercially in cool and dry weather. This study evaluates the performance of Psyllium husk as an environmentally friendly additive in water-based mud. Psyllium husk is added to pure water at various concentration to prepare water-based Psyllium husk mud. The optimal concentration of 0.75 to 1% by weight of Psyllium husk is found to have adequate rheological properties comparable with 5% by weight of bentonite. It has a fragile gel structure forming rapidly with time. Filtrate volume is reduced by 13% when Psyllium husk mud with a concentration of 1% by weight is used compared to the base bentonite mud. The insoluble parts of Psyllium husk create a very thin filter cake which are capable of blocking large pores to minimize the water loss into formations. Psyllium husk is more resistant to salinity of make-up water compared to the bentonite based mud and can develop higher viscosity when added to saline water. The advantage of Psyllium husk over currently used water soluble polymers such as Starch and CMC (Sodium Carboxymethylcellulose) is insoluble parts that can possibly block large pores and reduce filtrate volume. The laboratory findings of this research create a groundwork to use Psyllium husk as a viscosity and filtration agent in water-based drilling fluids and may facilitate further research and field trials.
Industrial Power Augmentation Technologies for Aero-Derivatives GT Used as Natural Gas Compressor Drives
Authors: Martinez Guillermo
Published: November 2016

Gas Turbines are widely used for Mechanical Drive applications, especially compressor drive for LNG Plants. Aero-derivative turbines are increasingly used for this application as they offer many advantages in terms of superior efficiency and fast start up and reaction to changing demand. However, aero-derivative turbine are highly ambient dependent. When the weather gets hot, gas turbines lose up to 20-40 percent of power output and consequently the production of the LNG plant decreases. Efficiency also decreases when the ambient temperature is higher.

The high ambient dependency of aero-derivative turbines has been the main drawback of this technology in very hot climates. Turbine inlet air cooling (TIAC) has been proven to be the solution for this challenge, especially in Middle East. The technical background behind this phenomenon is that aero-derivative turbines have a fixed volumetric inlet air flow. When the ambient air temperature increases the density of the air decreases and therefore the inlet mass flow decreases accordingly. As the power output of the gas turbine is proportional to the inlet air mass flow, for higher temperatures the output will be lower. With TIAC technologies, the inlet air is cooled to avoid the problem of high temperature and low density.

TIAC has been implemented in the power sector as a cost efficient power augmentation solution for more than 25 years but it is not common for gas turbines used in Oil & Gas fields because of two main reasons: ▪For the las years, Oil & Gas market was not so much concerned about cost▪Standard chillers are not able to comply with the high requirements of the Oil & Gas Industry

However, the falls in oil price are forcing the industry to find solutions for capital cost reduction, which together with the state-of-the-art TIAC technologies characterized for using API standard industrial compressors, is recently turning TIAC a cost effective needed technology in the Oil & Gas sector. Initial examples include the last greenfield developments made by Saudi Aramco and Gazprom in which TIAC technologies has been considered and successfully implemented to reduce the overall capital cost.

After several years of successful operation and data collection, the results of the TIAC system implemented in three LM6000-PC located in the North of Mexico will be presented. The power output and heat rates were measured with and without cooling, and the CAPEX and OPEX was evaluated and compared with the installation of a new gas turbine. Based on those results, it is found that capital and operation cost is significantly reduced with TIAC for aero-derivative turbines at Oil & Gas fields.
NAD 360 Management Tool - An Innovative Approach for Reducing Risk of Non-Accidental Death at Labour Camps
Authors: Qureshi Farrukh , Karyum Hanafi , Al Blooshi Maha
Published: November 2016

Objectives/Scope

An innovative, universal, and first-of-its-kind management tool was developed that helps minimizing risk of Non-Accidental Death (NAD) at labour camps. NAD 3600 Management Tool supports prevention of NAD by ensuring proactive implementation of a comprehensive healthcare system at a defined level of effectiveness and periodic measuring and monitoring of capabilities and performance of a Contractor in provision of emergency healthcare facilities at worksite and camp. Tool can also be used for investigating a case of NAD.
An Innovative Technique for Relative Permeability Estimation of Tight Porous Fractured Limestone Formation- Laboratory and Numerical Simulation Studies
Authors: Aljehani Abdulrahman S. , Doonechaly Nima Gholizadeh , Rahman Sheik S.
Published: November 2016

This paper presents a new and innovative approach for the estimation of relative permeability of porous fractured carbonate rocks. The presented method differs from previous studies in that the relative permeability estimation for three different systems that exists in fractured rocks is measured. Fracture, matrix, as well as fracture-matrix porous systems are all taking into account with laboratory measurements of relative permeability and capillary pressure. In this study, both steady and un-steady states are used for the estimation of relative permeability in addition to the produced water during drainage flooding. Fracture surface topography is imaged by the use of surface scanning technique to determine the asperities of the surface and their heights. Simulation based on Reynolds equation is considered when developing the mathematical formulation of multiphase flow simulation. The developed mathematical model based on the integration of Darcy, cubic law and Reynolds to account for the variation of different porosity systems. The results simulated numerically are in a good agreement with the laboratory.
Geomechanical Solutions for Drilling Through Challenging Nahr Umr Shale at High Angle: A Case Study From Offshore Field, Abu Dhabi
Authors: Xi Guifen , Singh Rudra , Haddad Mohamed , Lecoq Thierry Francis , Al Badi Bader Saif , Zahaf Kamel , AL-Kindi Rashid Khudaim , AL-Wahedi Khalid Ahmed , Leblanc John , Singh Hemant , Perumalla Satya , Salter Tim , Imtiaz Saad , Kirby Cliff , Paila Phalgun
Published: November 2016

ADMA-OPCO has undertaken a prestigious campaign to drill a large number of wells from artificial island in ABC field, most of these wells are extended reach drilling (ERD) wells with step-out up to around 18,000 ft. Operational efficiency/costs for drilling ERD wells is highly dependent on the wellbore stability, especially while drilling through the problematic Nahr Umr shale at different deviations and azimuths. Nahr Umr shale has a known history of causing wellbore instability in UAE and the surrounding countries and therefore a geomechanical study was initiated to understand the geomechanical setting in ABC field as well as fluid-rock interaction between drilling fluid and Nahr Umr shale formation. The main objectives of this geomechanical study were to optimize well design and drilling fluids in order to drill through Nahr Umr shale interval efficiently, additionally estimation of sustainable pressure variation that major faults can take without being reactivated was also performed.

An integrated geomechanical study including a 3D geomechanical modeling was carried out, in order to ensure drilling through Nahr Umr shale formation efficiently. This study covered formation petrophysical characterization, chemical tests on cuttings from Nahr Umr shale, chemo-poroelastic modeling, weak bedding analysis and also faults reactivation analysis.

Based on the study mentioned above, both customized drilling fluids program and suitable mud weights were optimized to stabilize Nahr Umr shale, and mitigate different types of wellbore instability issues. In addition to mud fluid optimization, the sustainable pore pressure variation was also estimated for several major faults.

A successful drilling campaign is in progress; so far many deviated wells have been completed without any noticeable troubles while drilling through Nahr Umr shale. This geomechanical model is helping to implement an effective drilling program for a smooth well placement. A learning curve has been building up continuously for handling more complex well trajectories successfully in the future. From this study, it was realized that, not only fluid-rock interaction and geomechanics related factors need to be taken into consideration for stabilizing a wellbore, but also special attention is needed for the existing micro-fractures within the formation, where increase in mud weight may make hole condition worse. A balanced approach has been adopted including drilling fluid optimization in order to avoid possible multiple failure mechanisms.
Heat Stable Salts Accumulation in an Acid Gas Removal Unit
Authors: O'Neill Stephen
Published: November 2016

Objectives/Scope

During 2015 a marked increase in the concentration of heat stable salts (HSS) within amine circulating around this unit was observed. This paper will present how the root cause of HSS accumulation was identified and addressed and also provide feedback from amine analyses indicating the concentration of individual HSS components that were identified to have been the main contributors to accelerated corrosion of the unit in this instance.

Methods, Procedures, Processes

An Acid Gas Removal Unit (AGRU) was installed within the Dolphin Energy onshore gas plant to remove H2S and some CO2 from raw gas prior to further processing. 

Results, Observations, Conclusions

A root cause analysis identified that a failure of the nitrogen blanketing system on the Lean Amine Storage Tank had been the origin of this HSS accumulation, and measures were taken to avoid any future re-occurrence.  However, the resulting high HSS concentration in amine had already begun to cause accelerated corrosion of the unit, in particular within the AGRU Stripper Reboilers.

Novel/Additive Information

The paper will be of interest to all those involved in the design and operation of Acid Gas Removal Units and to those involved in the reclaiming of amine within such units.  It will add to the body of literature already available from others that have experienced similar problems resulting from increased HSS concentrations in amine within AGRU's.
Optimizing Well Location in Clastic Reservoir Using Seismic Inversion for Onshore Field Located South-West Abu Dhabi
Authors: Ghafri Thuraya Al , Neves Fernando , Lakhlifi Assia
Published: November 2016

One of the target formations of the studied field is a clastic reservoir of the Middle Cretaceous. This particular formation is comprised of multiple sand units (bars, channels), with varying thickness and lateral discontinuity, separated by thin shale intervals. Due to data limitation and complex depositional environment, the delineation and reservoir characterization of this clastic sequence is relatively complex. This paper describes the workflow used to extract information about the acoustic properties (acoustic impedance) of the target formation and infer additional knowledge of the reservoir properties (porosity) using a model-based deterministic post-stack seismic inversion.

The area of interest (AOI) is covered by a recent high quality 3D seismic survey which has been processed through true-relative amplitude pre-stack time migration. Few wells containing monopole sonic, density and gamma-ray logs were available in the AOI. A basic feasibility study comprising rock physics, 1D well-log based seismic forward modeling, seismic-to-well tie and wavelet extraction was carried out prior to running model-based acoustic impedance inversion. The input seismic volume was post-stack pre-conditioned prior to inversion in order to enhance the usable frequency bandwidth and to reduce residual noise. Several techniques (with and without wells) were used to extract the seismic wavelet. A range of background (low-frequency) models were constructed using different methods and their impact on the inversion was appraised with the assistance of blind wells and classical inversion diagnostics.

The resulting average map and cross-sections of acoustic impedance (AI) enabled to locate the areas of high porosity (low AI) within the target formation. Consequently, in addition to seismic interpretation, we could optimize the location of the candidate well within the high porosity area. The generated AI helped in refining the seismic interpretation of this clastic reservoir as well.

Despite the complexity and the unpredictability of the Clastic reservoir depositional environment, Post-stack seismic inversion was a powerful tool that helped to locate the areas of good reservoir quality and ultimately to optimize the location of the candidate well.
Generating Cost Reduction in the Supply Chain by Coupling Surface Facilities with Reservoir Data in Integrated Asset Modelling
Authors: Harley John , Abel Clive , Watson Martin
Published: November 2016

Integrated Asset Modelling (IAM) processes can be used to quantify and monetise reservoir potential during the concept design process. Through quantification, risks can be mitigated and managed to deliver greater certainty through the concept selection process. IAM can be deployed throughout the hydrocarbons upstream sector to deliver robust field development and concept design solutions with more robust project economics.

IAM offers significant value and potential to identify supply chain cost reductions across the full spectrum of upstream developments, from full field development planning to individual equipment item modifications. The process offers particular value in development planning; in identifying and assessing sensitivity options and in definition of the optimum concept.

Full IAM incorporates expertise in reservoir, flow assurance, facilities and project economics expertise into a single integrated asset model. The process defined here is most effective as it is built upon integrating industry and in-house software, a combination of which facilitates Life of Field analysis to be carried out within a single package. The process offers unparalleled speed and flexibility in identification and analysis of concept design sensitivity cases. The IAM approach offers significant advantages and benefits to operators in addressing the three main reasons for destruction of project value; poor estimation of reserves, schedule overruns and cost overruns.

This IAM process is configured for fast and robust evaluation to ensure the right decisions are made at the right time based on the right information. The process will therefore preserve project value for operators and reduce the risk of value erosion through over or under engineering, or project recycle.
A Robust and Environment Friendly Artificial Lift System: ESPCP with PMM
Authors: Zhu Shijia , Hao Zhongxian , Zhang Lixin , Wang Quanbin
Published: November 2016

Up to 2015, the number of oil wells has reached more than 200,000 for CNPC. It is estimated that conventional beam pumping units are applied to 87% of wells. The traditional pumps suffer from eccentric wear between sucker rod and tubing and high electricity power cost, especially for deviated and horizontal wells. In this paper, we introduced a new artificial lift system, electric submersible progressive cavity pump (ESPCP), to solve these problems.

The new system includes a progressive cavity pump driven by a downhole permanent magnet synchronous motor (PMM), the motor protector and flexible shaft connecting the pump and the motor. In the design no gear reducers is used, which is the most likely failure point, in order to increase the robustness of the system. The motor protector is filled with oil for the lubrication and cooling of the motor. The speed of motor can be adjusted by frequency inverter on the ground from 50 to 500 rpm according to the liquid producing capacity. The operators can remotely control the working state of the system and the running data can be transmitted to the server in the remote office.

We have used the ESPCP systems on 4 troublesome wells for field trials in Jilin oil field. The results show that the system can save more than 20% of the electricity power and double the working life comparing to the traditional beam pumping unit system. Moreover, the system is located at the bottom of oil well, so less site occupation and less noise pollution to the environment are achieved.

The low electricity power and less frequent workover operations can reduce cost especially for the low oil price period. This paper will elaborate on the key learnings based on these field trials.
Successful Well Testing Operations by Using a Single Trip Retrievable Isolation and Testing Packer in Ghasha Appraisal Well Offshore Abu Dhabi
Authors: Jimenez Jose , Slatewala Huzefa , Negron David , Huda Shamshul
Published: November 2016

The discovery of offshore sour and corrosive gas reservoirs and the need to satisfactorily drill and produce them began in the late 1950's. The Ghasha 15 well includes deep oil / gas reservoirs containing up to 38% H2S and 7% of CO2. The objective was to perform safe and efficient drilling and several well testing operations in a highly corrosive environment with a rig that was located in a stand-alone offshore location in Abu Dhabi. The well was an exploration well in a location considered wild or remote well; there was no tower or platform facility with pipe lines to support the well testing operations available. 14 x well drilled previously were unsuccessful in obtaining the necessary reservoir data to prove deliverability. These challenges required the use of state of the art technology and highly reliable down hole equipment to subsequently enable successful exploration & appraisal of future UAE giant gas field development optimization.

Among other down hole tools and surface equipment used, highly sophisticated DST tools including HPHT high integrity packer, acoustic wireless telemetry systems, Dual Ported Slick Joints (DPSJ), flanged connections, surface close loop well testing package, special H2S and fire & gas detection systems and dispersion modelling were designed to successfully deliver the required data for field developments.

Attention to detail, rigorous planning, team work, multidiscipline input and approach were some of the key success factors in delivering the objectives in a safe and efficient manner.

While many drilling, data gathering, surface and down hole tool solutions were employed, this abstract will focus solely on the packer equipment and deliverability
Lesson Learnt from Immiscible Gas Injection Pilot in Offshore Carbonate Reservoir
Authors: Agrawal Pawan , Kumar Jitendra , Draoui Elyes
Published: November 2016

Hydrocarbon gas injection projects are undertaken in order to maintain reservoir pressure, produce oil through swelling and reduce residual oil saturation by decreasing the interfacial tension (IFT). Along with local displacement efficiency, macroscopic sweep efficiency plays a dominant role in the success of gas injection projects, as recovery from the field depends strongly on reservoir geology and petrophysical properties.

In this paper, a case study of one of the hydrocarbon gas injection pilots is discussed as the performance of the other two pilots has already been described in Kumar et al. 2015a. A five-spot pattern hydrocarbon gas injection pilot in tertiary mode has been carried out in a giant carbonate reservoir offshore Middle East, which has long peripheral water injection history. A comprehensive monitoring plan, including an observer well, was applied through time-lapse saturation logging, single well chemical tracer test (SWCTT), pressure measurements, production testing, and tracer campaign to assess the pilot performance and minimize uncertainties before large-scale application.

This paper presents the overview of the pilot, monitoring plan and the findings which include microscopic and macroscopic sweep efficiency. The pilot areal sweep performance was affected by the existing pressure gradient of peripheral water injection while the vertical sweep efficiency was strongly affected by the reservoir heterogeneity. At the cessation of the pilot, a value of 6 ± 3% was measured from SWCTT in the producer well, which shows the robustness of the gas local displacement efficiency. The history match performed indicates that for the same pilot, the performance can be improved using horizontal line drive in place of five-spot pattern and it can further be enhanced through water-alternating-gas (WAG) injection. The learning from the three gas injection pilots is used in re-designing the future large-scale development plan and is described in details in Kumar et al., 2016a and 2016b.
New Drill Bit Technology Sets Drilling Records in Carbonates and Harsh Rock Applications
Authors: Rahmani Reza , Bradford John , Barocio Hector
Published: November 2016

Harsh rock applications in general, specifically carbonates, are challenging in many aspects: 1) A combination of rock ductility and high strength contributes to low rate of penetration (ROP) in carbonates. 2) Applications are generally interbedded. 3) Significant thermal degradation of the cutters, especially in the shoulder area of the PDC bits, costs companies premature bit wear and unwanted extra runs. This paper presents the development of a new drill bit technology that addresses those challenges.

More than 40 pressurized laboratory experiments were conducted on Carthage limestone to identify proper positioning of a new shape cutter for carbonate applications. Furthermore, computational fluid dynamics (CFD) coupled with finite element analysis (FEA) were implemented to evaluate solutions to prolong the thermal life of the PDC cutters. This resulted in development of a novel nozzle geometry to cool and clean primary cutting structure as well a dedicated flow path for the secondary cutters. After successful laboratory testing, the new product and features were tested in several field applications in both North America and Middle East.
A Design for the Evaluation of a Waterflood EOR Technique by Single-Well Chemical Tracer Test in an Offshore Environment
Authors: Webb Kevin , Marrion Maynard , Stapley Jon , McCormack Martin , Williams Dale , Salino Pete , Al-Busafi Badar , McNeilly Kevin , Yammahi Fatmah
Published: November 2016

Single-well chemical tracer tests (SWCTT) have proven to be a valuable technique for evaluating Enhanced Oil Recovery (EOR) responses in clastic reservoirs. Development of carbonate waterflood EOR technologies are relatively immature in comparison, but the use of SWCTT for providing evidential basis in the field promises to be quick and relatively inexpensive compared with inter-well trials.

SWCTTs measure the remaining oil saturation (Sor) to waterflood at a 15-20 feet distance from the wellbore. The technique indirectly measures the Sor by analysing back-produced fluids for partitioning tracers in a well which is producing at 100% water cut. Completing the test pre- and post-EOR treatment quantifies the EOR benefit, at least in that near-well region.

Laboratory studies suggest that the use of ionically designed waters for EOR in carbonate reservoirs is temperature sensitive. This makes the design of a single-well test complex as it is essential to understand the thermal behavior of the well and the near-wellbore reservoir during any sequence of SWCTTs. Commercial simulators were used to investigate the thermal characteristics of the well and the near-wellbore reservoir respectively. These simulation results were also benchmarked against a water injection trial in another analogous well. The results showed that to ensure the temperature in the near-well region is kept sufficiently high to trigger an EOR response, it is necessary to pre-heat the injection water to >100°C. This is a complex operation especially offshore where the technical and HSE considerations need to be integrated into a sufficiently-sized heating system where space may be limited. Artificial lifting of produced fluids from a well which is producing at 100% water is also problematic offshore. Benefits and drawbacks of various lift options will be reviewed. The effect that delays during the production phase can have on the quality of data from the SWCTT will be shown as well as the options considered to reduce the likelihood of such problems occurring.

The need to test this EOR technique in a controlled manner places stringent requirements on the surface facilities to deliver a test within the design specification. The need for low salinity water injection led to the selection of an integrated water treatment system able to produce desalinated water on-demand.

This paper is the first of a series of papers aimed at describing the development of an ionically designed waterflood EOR technology for a giant carbonate oil field.
Establishing an Energy Baseline for Drilling Contractors – An Opportunity for Huge Savings Environment and $$
Authors: Pushkarna Arun , Al Mulla Hind , Elbadiich Akram , Hendawy Mohamed , Badenhorst Petrus , Chandran Dileep , Ricaplaza Archie
Published: November 2016

As a drilling contractor when NDC opted to put in place an Energy Management system it became imperative to establish a baseline of energy consumption so that improvement of energy practices could be measured against this baseline. The task was entrusted to DNVGL Noble Denton. But this posed a unique challenge because very little work had been previously done in the field of energy management by drilling contractors across the world. Due to this ready reference material was not on hand that could be adapted to achieve the baseline study. This paper explains the process adopted by both companies and the outcome of the effort.

The task was approached by first preparing an inventory of the energy consumers across the company. Because the company owned assets stretching across Onshore and Offshore, real estate and transport vehicles, the assets were first grouped into various types. These were: Onshore RigsOffshore RigsCentralized crew campsHead Office BuildingsWarehouseWorkshops, andTransportation assets

Then a sample of each type of asset was visited and the main energy consumers identified. The energy consumption patterns of these assets was then examined to arrive at a specific consumption value that could serve as a baseline for continuous improvement.

The challenges of identifying a typical energy demand for drilling rigs arose from the fact that the energy demand was greatly influenced by the vagaries of the drilling program, type of well, operational practices etc.

Overcoming these challenges required that assumptions be made to rationalize the data so that it could be applied across the company assets.

The baseline energy audit was successfully concluded and areas for improvement were meaningfully identified.

This was the first time that a baseline energy audit for a drilling contractor had been prepared and it has paved the way for other drilling contractors to benefit from the effort. Not surprisingly the audit revealed that the major consumers were the rig engines and thus the maximum benefit could be realized from focusing the company energies on managing these engines. Naturally other easier to implement options exist and have been identified for improving the energy consumption

This is the first effort at establishing an energy consumption pattern for a drilling company in the region and is likely to become a trend very soon because the adoption of the recommendations can be easily and quickly translated into savings for the company running into millions of dollars.
Simulation Study on Influences of Wellbore Tortuosity on Hole Cleaning in Extended-Reach Drilling
Authors: Naganawa Shigemi , Kudo Hiroyasu , Matsubuchi Hitoshi
Published: November 2016

As widely known, wellbore tortuosity or spiraling can lead to the trapping of a cuttings bed in a trough of a tortuous hole, thereby leading to poor hole cleaning in extended-reach drilling. The objectives of this study included quantitatively evaluating the influences of wellbore tortuosity on hole cleaning and cuttings transport behavior in extended-reach drilling. Additionally, the study provided a recommendation of effective drilling practices. The study involved performing hole cleaning optimization studies for an extended-reach well with a long horizontal section aiming for a maximum reservoir contact, using a transient cuttings transport simulator. The planned trajectory of the well was assumed to have a certain degree of wellbore tortuosity in the horizontal section. The pump rate and bottoms-up circulation operation were optimized based on parameter studies and additional transient simulations by considering the effects of penetration rate and variation in cuttings size.

Simulation results indicated the formation of a considerably high cuttings bed, particularly in the down-dip intervals (up dip in mud flow direction) at an insufficient pump rate. The height of 1/3 to 1/2 of the drill pipe diameter could be potentially buried in a cuttings deposit bed, and this results in a hole packed-off or a stuck pipe. A higher rate of penetration can cause insufficient hole cleaning. In this case, control drilling that maintains a reasonable low penetration rate may be effective. Furthermore, borehole breakout may enlarge hole diameter and generate large-sized cuttings. Both of these have negative impacts on hole cleaning, and thus, borehole stability and smooth wellbore trajectory controls should be carefully considered. To clean these holes, frequent bottoms-up circulations were effective at each stand of drilling even if the optimizations of other drilling parameters were limited. The findings also revealed that accumulated cuttings in a tortuous wellbore were trapped in the trough of the hole and that the bed height of locally trapped cuttings in the down-dip intervals could be much higher than that indicated by previous studies.
Robust Completion and Stimulation Design Methodology to Maximize Well Performance for Long Horizontal Laterals in a Giant Off-Shore Field Development
Authors: Al Hosani Fahad , Amin Alaa , Ali Yasser , Al Kiyoumi Ahmed , Sau Rajes , Beckham Richard , Shuchart Chris
Published: November 2016

A giant oil field offshore has been developed to date using vertical and then horizontal wells drilled off-shore from wellhead platform towers. In order to reduce costs reducing the number of wells required to drain the reservoir with improving recovery, further development of the field was planned using extended-reach long horizontal wells with throws greater than 18,000 ft and measured depths greater than 25,000 ft with some wells exceeding 35,000 ft.

This paper will discuss how to reach an integrated robust completion design methodology to maximize performance of these long horizontal wells. The methodology considers a combination of two essential designs; Lower completion design and Stimulation design.

While the key objective of lower completion and stimulation designs has been to connect wells to reservoirs at their best performances with the most effective and economical way, productivity/injectivity from every foot of these long laterals as well as long term performance are the keys to successful well design and reservoir development strategy. The design methodology incorporates several constraints from reservoir such as heterogeneities in permeability, pressure and porosity, and uncertainties in those properties prediction including presence of faults/thief zones. The design methodology also incorporates the objective to be able to perform well surveillance, such as PLTs, as well as manageable installation of lower completion. The paper will give examples of application of this methodology in designing a10,000+ ft long limited-entry liner which facilitates bullhead high pressure – high rate stimulation – high acid concentration in order to place acid across the entire lateral and maximize stimulation effectiveness of every foot of the lateral. The paper will also discuss actual well performances of available long lateral wells along with lessons learned.
Laboratory Scale Studies to Understand the Variation of Fracture Toughness with Acoustic and Other Rock Mechanical Properties
Authors: Talreja Rahul , Kumar Rajeev Ranjan , Subbiah Surej Kumar , Murthy V. M. , Munshi Shri B.
Published: November 2016

One of the main rock mechanical properties required for all design applications is fracture toughness. The fracture toughness values are helpful for simulation of hydraulic-fracture propagation, drill energy requirements, drilling rate prediction, wear rate etc. In this study fracture toughness testing of rock with core based specimens was performed with an emphasis on chevron shaped notches specimen. The same rock sample were then subjected to different small scale rock mechanics laboratory tests to determine various mechanical properties like drilling rate index (DRI), compressional slowness, uniaxial compressive strength and tensile strength of the rock. An outline of the methods used is given in the paper. Based on the data obtain from these tests, correlations are established using regression analysis between fracture toughness values and determined rock mechanical properties. This study provides empirical correlations, which will be helpful in estimation of fracture toughness for sandstones and siltstone.
Tablet-Based Mobile App Software Provides Precise and Instant Bit Selection in the Field
Authors: Roberts Danielle V. , Lee Roger K. , Aldarweesh Ayman M. , Agawani Waleed
Published: November 2016

Hydrocarbons from across the world are being explored every day. Significant effort is spent in optimizing the bit selection programs which may comprise a large number of bit design iterations. A large inefficiency is created because of the nonexistence of a quantitative method of relating these drilling applications and bit designs. This organization launched a new mobile drill-bit selection tool to enable faster, more-scientific, bit-selection decisions in the field.

The tool incorporates breakthrough methods to relate drilling applications and PDC bit designs to a comprehensive set of common quantifiable and measurable behaviors. The methods improve bit selection outcomes by focusing on application requirements and bit performance capabilities instead of traditional methods that focus on bit features such as cutter size, blade count and gauge length. Individuals enter drilling parameters as well as application behaviors that characterize the formation to be drilled. The optimum bit is then selected by a proprietary algoritm. The mobile app can draw on the full database of drill-bit data, and provide technical drilling solutions in a matter of seconds at the touch of a fingertip.

The innovation of this tool is its ability to quantitatively compare drill bits side-by-side with full knowledge of bit behaviors, instead of solely comparing the bit features that lead to those behaviors. With traditional methods, the benefits and tradeoffs of altering bit features were estimated by field personnel using technical intuition and past experience. By using the bit selection app, a quantified and technically justified comparison is achievable by individuals with all levels of experience. Applications can now be efficiently compared to other applications in various geographic locations to drive synergies for bit selections and drilling practices. Now, learnings from one application can be transferred to other bit selections and applications regardless of application type or location. Finally, the behavior methodology of this tool promotes the ease of technical communication between multiple user groups such as geologists, design engineer, field personnel and drilling operators, leading to a faster, more-accurate drilling optimization process.

The tool is the first mobile application in the oil and gas industry that combines historical engineering data with creative digital designs, enables an intuitive user interface, 3D modeling and real-time database search capabilities. Individuals of all levels of expertise have instant access to necessary information to make bit selection easier. The authors will present value-added case studies from the Middle East region.
Unconventional Fracturing Fluids for Unconventional Reservoir Challenges
Authors: Bukovac Tomislav , Akbari Aulia , Gurmen Nihat M. , Mehrotra Nagendra , Alabi Ibrahim , Orellana Roland , Arcano Nelson Suarez
Published: November 2016

To overcome the challenges specific to unconventional reservoirs that are being targeted across the Middle East region a synergy of unconventional technologies is needed. Fracturing fluids are one of the critical components of multi stage proppant fracturing solution when targeting extreme HPHT reservoirs while aiming to preserve freshwater. The objective of this paper is to reveal the performance of unique fracturing fluids that have been recently tailored and applied to tackle tight and unconventional reservoir challenges.

Three very different unconventional: polymer-free, carboxymethyl hydroxypropyl guar (CMHPG) and poly-acrylamide based fracturing fluids are presented in this work. They have been field-tested and recently successfully applied in the tight and unconventional reservoirs of UAE as well as the Middle East and Asia. These fracturing fluids collectively address the full spectrum of existing and future reservoir target bottom-hole temperatures ranging from 50 degF up to 450 degF. The unique chemistry characteristics for each of the fluids will be elaborated together with laboratory test results that will include compatibility, rheology and other qualification tests. Furthermore, results of extensive qualification tests performed to address specific local challenges will also be presented.

All three fracturing fluids were effectively applied leading to treatment success and proving their performance in extreme reservoir temperature, stress or operational environment that demands high-efficiency. Each fluid proved compatibility with used mixing water and reservoir fluids tested. These fracturing fluid types can be continuously mixed simplifying operation, reducing fracturing equipment layout and minimizing waste. All these improvements are critical in an offshore operating environment. Polymer-free and CMHPG based high viscosity fluids are formulated with sea water to minimize environmental impact. Furthermore, these fluids are continuously mixed with seawater addressing the conventional fracturing fluid logistic constraints offshore. These key improvements made massive offshore and multi-stage proppant fracturing treatments technically and economically feasible.

The novel unconventional fracturing fluids elaborated in this paper offer a set of unique technical capabilities that did not exist previously. These three fluids are critical technology enablers and they are part of a multi-disciplinary, integrated technical collaboration project aiming to efficiently and effectively address local complex subsurface conditions and stringent economic requirements of remote offshore operations.
Innovative Approach for Class Certification & FFS Assessment of Spm'S
Authors: Al Shehhi Saif , Al-Sayed Talal A , Al Hammadi Hassan , Al Dhanhani Khalfan , Kallinkil Shammas
Published: November 2016

Offshore Tanker loading buoys,(SBM's) are lifeline of oil and gas business. Periodic inspection and class certification is critical for the integrity assurance of these tanker buoys. However to be in line with class requirements, the mooring chain has to be subjected to dry dock inspection every 5 years. This requires shutting down of buoys, dismantle mooring chain and send to dry-dock for inspection. This also incurs huge cost in hiring barges and resources to carry out these activities.

The whole process become trickier when your buoy is continually loading throughout the year, as in the case of ADMA OPCO's and don't have a spare buoy to offset the loading activities.

To overcome this challenge ADMA in collaboration with classification body DNV introduced advanced inspection technologies and assessment techniques which allowed for in-situ inspection and class certification of the buoys saving huge cost and production loss.

With this approach ADMA was able to carry out detailed fitness for service assessment for tanker buoy in line with our engineering division and generated a comprehensive asset certificate or passport in ADMA OPCO's term highlighting the asset condition, remnant life, mitigations required etc. for Loading Buoy the first time.
Evaluation of Porosity and Permeability in Lower Cretaceous Carbonates in UAE Using NMR Measurements at Laboratory and Reservoir Conditions
Authors: Hassall J. K. , Zakaria A. S. , Shtepani E.
Published: November 2016

Objectives

The objective of this paper is to calibrate porosity and permeability derived from NMR logs to core measurements and thus allow improved porosity and permeability prediction from new and historic NMR logs. Permeability, and to a lesser extent porosity, are the most important parameters in determining the potential production of a reservoir. Measuring these parameters accurately is challenging in carbonate formations due to heterogeneity and the wide variety of pore classes, such as interparticle porosity, moldic porosity, vuggy porosity, and microporosity. Traditional density-neutron and sonic tools used to measure the porosity are strongly dependent on lithology which might yield incorrect porosity measurements. NMR logs, while largely independent of matrix properties, can potentially underestimate microporosity. No wireline tool is capable of continuous permeability logging.

Methods

In this study, we provide an assessment of NMR measurements at laboratory and reservoir conditions to allow improved estimation of porosity and permeability. The formation under investigation is largely limestone, with negligible dolomite or clay – but has a large range of pore structures. Several samples from different rock types were selected for this study. These were investigated with computed tomography scanning, thin section analysis, and high pressure mercury injection capillary pressure (MICP) tests. NMR T1 and T2 measurements on fully formation water saturated samples were then conducted at laboratory and reservoir conditions. Finally, to define the bound and free water, and determine appropriate T2cutoff(s) for each rock type, samples were desaturated to irreducible water saturation (Swi) using a centrifuge technique, followed by NMR T1 and T2 measurements at Swi at reservoir conditions. Additionally, the laboratory NMR measurements are compared to wireline log NMR measurements at the same depths.

Results

Pore size distributions from NMR measurement agree well with those derived from MICP tests. The NMR measurements on desaturated samples showed that Swi and the corresponding T2cutoff vary from sample to sample. Possible controls on this will be discussed. The results from this study showed that T1 measurements confirm T2 responses: both are strongly dependent on temperature, but less dependent on pressure.

Novel Information

A strong 1 to 1 correlation between helium porosity, φHE and NMR porosity, φNMR was observed demonstrating that in this formation under recording of microporosity is not an issue. Based on NMR data, permeabilities were calculated using both the Coates and SDR models. It was found that the Coates model gives good agreement with permeabilities measured on core plugs by the standard laboratory techniques.