bluuebunny/crossref_metadata_2025 huggingface dataset:
Drilling Waste Reduction and Improved HSE on Maersk Giant Utilising Revolutionary Lightweight Vacuum Conveyor System
Authors: Kroken Asbjorn , Vasshus Jan Kristian , Grelland Tore
Published: February 2015

Description of the Proposed Paper:

Effective removal of contaminants from drilling fluids is widely accepted as a key factor in achieving optimum drilling performance and reducing fluid cost - but it also plays a critical role in minimizing environmental discharge. This paper describes the development, qualification, field testing and full scale systems results of arevolutionarysolids control solution that provides advances on several aspects that conventional equipment is infested with. The findings presented are based on results obtained on the full scale system utilized on Maersk Giant, located in the North Sea.

Application:

The introductionof the VCS system on Maersk Giant have demonstrated a substantial reduction in fluid adhesion on cuttings, improved filtration resulting in reduced operational cost.

As the focus on HSE in the drilling environment continues to intensify, drilling technologies must adapt to meet governmental and industry standards. With the lightweight vacuum conveyer system (VCS)described here, operators now have a revolutionary way to handle drilling fluids and solids. Studies and field tests show that it provides a significant improvement in safety and environmental risks during drilling operations.

Results, Observations, and Conclusions:

This intelligent fluid management system makes a positive impact on HSE conditions for onshore and offshore workers in the following ways:Health benefits:Elimination of oil mist/vapor and chemical exposure to personnelElimination of vibration: No need for structural reinforcement because of weight and structural low frequency vibrationNoise reduced to 68 dBA, well below recommended NORSOK standard of 83 dBA (for 12 hours working day)Safety benefits:No gas (H2S) releasedEnvironmental benefits:Less mud discharge offshoreLess waste liability

Significance of Subject Matter:

Reducing waste, costs, and health, safety and environmental impacts are always top of mind within the petroleum industry. For decades, the same shaker technology was used with no viable alternative. Today, engineers can benefit from increased production, lower waste, cost and environmental impact with the MudCube. Deployment is easy, proven and effective - and the time to act is now.
Optimum Well Completion Strategies in Tight Oil Reservoirs
Authors: Saputelli Luigi , Chacon Alejandro , Lopez Carlos
Published: February 2015

Hydraulic fracturing is currently the completion of choice in most tight reservoirs; however, the ultimate performance of fractured wells is severely affected by the interfering effects inside the fracture and inter fractures. Previous simulation studies investigated the effects of well spacing and fracture length on well productivity in low-permeability oil and gas reservoirs. It was shown that the most important parameters for determining the optimum fracture length are the formation permeability and the stimulated reservoir volume.

Although a number of studies have examined the performance of horizontal fractured wells and fracture geometry effect, fracture spacing and intersecting angles in vertical and horizontal wells should be further investigated.

This study presents the results of a tight oil reservoir in the Bakken shale. Reservoir parameters considered include local rock stresses, rock compressibility, absolute and relative permeability, and porosity. The well-completion parameters included fracture length, height, width, conductivity, number and spacing between fractures, fracture intersecting angle, and cased vs. open-hole completion. Fracture modeling considered rigorous description of the hydraulic fracture properties and finite difference reservoir modeling.

Economically attractive reserves recovery were modeled through multiple fracture placements in a 10,000 ft horizontal well. Numerical simulation showed that oil recovery increased between 8 to 15% while net present value (NPV) increased 8 to 24%, as the number of fractures increased. Based on the critical assumptions in the study (permeability, natural fracture distribution and stress orientation), an optimum number of fractures was identified. Open hole completions provided better performance in most cases, and recovery was greater for a higher number of contributing perpendicular vs. longitudinal fractures.

The results of the study may hopefully be used to improve the understanding of the role of fracture geometry, spacing and open/cased-hole completion strategy to enhance operators optimum completion design.
Ultra Deepwater Managed Pressure Drilling in Challenging Formations
Authors: Malt Roar
Published: February 2015

Ultra deepwater drilling is challenging. When easily fractured carbonates are encountered, the challenge increases further still. High hydrostatic pressures, as well as the narrow gap between pore and fracture pressures, add to the complexity. Performing successful cementing operations is equally challenging.

This paper describes the drilling of a well at 2180m in the eastern GoM. The formations were carbonates with potential for high-to-total losses. The rig was a new Sixth Generation DP MDU. To manage the BHP and prevent losses, the rig had been equipped with a new type of DGD/MPD system; a pumped riser system, with the pump mounted around 400m below the bell nipple. The pump reduces the riser level in a precisely controlled manner to manipulate the BHP as required.

Due to a very weak 20"shoe the 17 ½" section had a drilling window of only 0,3ppg. The pumped riser system was used to drill the section with nearly constant BHP, compensating for the ECD by manipulating the hydrostatic column level while drilling and bringing the level back up for connections. No losses were seen. The same applies for cementing of the 13 3/8 casing.

In the 12,25" section the system was rested due to robust formations and a generous drilling window but was used again successfully to ensure a good 9 5/8" cement job.

In the 8,5"section the pumped riser system was again necessary due to potential severe losses in weak reef-type carbonates. It soon became evident that this formation could not have been drilled conventionally as weak zones were penetrated at the start of the section. Loss pressure was 8,4 ppg. Drilling with returns was still required in order to get the required geological information from the well, which was achieved. As drilling proceeded a normal-pressured zone was encountered. The pumped riser system was used to balance the resulting pressures downhole with required returns to the surface.

The system was also used to perform a good Plug and Abandonment operation after TD was called.

This paper will describe the planning and drilling operation of the mentioned ultra deepwater well and present the operational results.
Weight Distributed SCRs with Quality Fabrication from Large Motion Floaters
Authors: Karunakaran Daniel , Jones Richard
Published: February 2015

Steel catenary risers (SCR) have been an attractive choice for deep-water field developments due to its simplicity. However, design of SCRs from large motion host platforms has been a great challenge. The key issues for the design of SCR in such conditions are the fatigue near hang-off and at touch down point.

Design of SCRs by distributing weight along the riser enhances the fatigue performance of SCRs thereby extends the feasibility of SCRs from large motion floaters, fulfilling both strength and fatigue requirement. The weight distribution along the SCR is obtained by fully qualified ballast modules and also fully qualified light weight add-ons at TDP which are designed for mud-line application. Further, by high quality welding and optimized weld geometry the fatigue performance of the SCR welds are improved and optimized. This paper also describes the mechanism that drives the weight distributed SCR design and also fatigue test data from optimized weld geometry.

The results clearly indicate that it is possible to have a robust design of SCRs from large motion host platforms using presently qualified material and technology. These qualified products extend the applicability of the weight distributed SCR concept to most dimensions and applications. This concept is also applicable in less demanding environments.

Fatigue test results will be presented from both carbon steel and clad/lined riser qualification programmes which will demonstrate that high fatigue performance can be sustained with established girth welding procedures with appropriate control of pipe fit up tolerances and weld soundness.

The weight distributed SCR concept combined with high performance weld, will make the applicability of SCRs a credible alternative option for use from host platforms with large motions. Since the ballast and light weight add-ons are fully qualified material they are cost effective and ready for project application.
Compact and Light Weight Equipment for Floating Production Systems
Authors: Sellman Erik , Mandewalkar Pavan , Sams Gary W
Published: February 2015

Floating production systems present special considerations considering both mechanical aspects and well as process aspects for the crude oil dehydration train.

The effects of sea heave produces fluid dynamic forces inside the treaters and also mechanical forces on the supports of the process equipment, which require special attention for the design of the treater internals, supports and instrumentation. In addition to the amplitude of the roll and pitch of the facility hull, the frequency of these movements has an equally important role.

Through the use of advanced fluid dynamic designs and advanced electrostatic technologies, the dehydration and desalting equipment on a floating production system can be made more compact, thus reducing the required footprint on the process deck as well as the weight load on the floater.

This paper describes special design considerations for dehydration and desalting equipment for floating production and how these process vessels can be drastically reduced in size and weight while still maintaining the required process performance. We will also discuss special considerations for instrumentation, slosh suppression and operating procedures, in addition to the potential for additional production from upgrading existing treaters.

The paper also includes case stories with examples of compact equipment installed on FPSOs, SPARs, TLPs as well as semi submersibles.

Company affiliation: Cameron Process and Compression Systems

Presenter: Erik Sellman, Sr. Product Manager (erik.sellman@c-a-m.com)
Multinomial Logistic Regression for Bayesian Estimation of Vertical Facies Modeling in Heterogeneous Sandstone Reservoirs
Authors: Al-Mudhafer Wathiq J.
Published: February 2015

Precisely prediction of rock facies leads to adequate reservoir characterization by improving the porosity-permeability relationships to estimate the properties in non-cored intervals. It also helps to accurately identify the spatial facies distribution to perform an accurate reservoir model for optimal future reservoir performance.

In this paper, the facies estimation has been done through Multinomial logistic regression (MLR) with respect to the well logs and core data in a well in upper sandstone formation of South Rumaila oil field. The entire independent variables are gamma rays, formation density, water saturation, shale volume, log porosity, core porosity, and core permeability.

Firstly, Robust Sequential Imputation Algorithm has been considered to impute the missing data. This algorithm starts from a complete subset of the dataset and estimates sequentially the missing values in an incomplete observation by minimizing the determinant of the covariance of the augmented data matrix. Then, the observation is added to the complete data matrix and the algorithm continues with the next observation with missing values.

The MLR has been chosen to estimate the maximum likelihood and minimize the standard error for the nonlinear relationships between facies & core and log data. The MLR is used to predict the probabilities of the different possible facies given each independent variable by constructing a linear predictor function having a set of weights that are linearly combined with the independent variables by using a dot product.

Beta distribution of facies has been considered as prior knowledge and the resulted predicted probability (posterior) has been estimated from MLR based on Baye's theorem that represents the relationship between predicted probability (posterior) with the conditional probability and the prior knowledge. To assess the statistical accuracy of the model, the bootstrap should be carried out to estimate extra-sample prediction error by randomly drawing datasets with replacement from the training data. Each sample has the same size of the original training set and it can be conducted N times to produce N bootstrap datasets to re-fit the model accordingly to decrease the squared difference between the estimated and observed categorical variables (facies) leading to decrease the degree of uncertainty.
Wettability Alteration by New Acid-Alkali-Surfactant-Polymer Formulation in High Salinity Carbonate Reservoirs
Authors: Kalwar Shuaib A. , Elraies Khaled A. , Kumar S. , Abbas Ghulam
Published: February 2015

Formation wettability is considered as one of the controlling parameters for residual oil recovery from carbonate reservoirs. It has a significant impact on reservoir rock properties - relative permeability and capillary pressures, and consequently on oil displacement in porous media. In this paper, wettability study is conducted by using contact angle and natural imbibition methods in the presence of acrylic acid, sodium metaborate, alpha olefin sulfonate and a copolymer. Acrylic acid was used as a precipitation inhibitor to sequester divalent cations from precipitation. The effect of different acrylic acid concentrations on interfacial tension reduction, polymer viscosity and wettability was also investigated using hard brine with a total salinity of 59,940 ppm. Various fluid-fluid interaction tests were first performed to find an optimum ratio of acrylic acid-alkali to prevent precipitations for 30 days at 80 oC. Based on the fluid-fluid and rock-fluids interfaces, it was observed that the combination of acrylic acid with ASP revealed positive impacts on the interfacial tension, solution viscosity and wettability alteration. Further, a considerable amount of oil was recovered during natural imbibition process. This implies strength of new Acid-Alkali-Surfactant-Polymer (AASP) formulation to alter formation wettability. Hence, AASP system can be a feasible and an alternative approach to conventional ASP flooding technique particularly for offshore applications in which hard brine or sea water might be used to prepare ASP slug.
Modelling and Imaging Through a Gas-Obscured Zone in Malaysia
Authors: Zhu Xianhuai , Sood Sanjay , McMahon Tim , Brewer Joel , Keys Robert , Mosher Chuck
Published: February 2015

Description of the material

The study area is situated SB311 block of Malaysia. The tectonic evolution of the area is linked to the rifting of South China Sea. The image of the target in this study is affected by the shallow gas-obscured zone in the overburden. The goal of this study is to investigate new acquisition techniques and parameters capable of imaging through the gas-obscured zones, using advanced modeling and imaging technologies.

Application

Based on regional geology and seismic data, two sets of models containing "geobodies" filled or partially filled with gas were built. The geobodies were constructed based on the characters of seismic amplitudes and stratigraphy, and they were distributed above and below the top of KBB formation. P-wave velocities (Vp), S-wave velocities (Vs) and bulk densities (ρ) inside geobodies were modified based on Biot-Gassmann fluid substitution and the Xu-White Differential Effective Medium (DEM) method. A 15m thick of unconsolidated low velocity materials was added to model immediately beneath the water bottom to investigate the feasibility of P-to-S converted wave recording.

Results, Observations, and Conclusions

Acoustic modeling and RTM imaging have suggested that long offset (>10 km) is required in order for undershooting. Any newly acquired long-offset 2D streamer data could not only have potential for imaging the base of KBB, but also assist reprocessing of existing 3D seismic data.

Elastic modeling followed by dual-velocity RTM has suggested that P-to-S converted waves have potential for imaging both top and base of the Kebabangan reservoir, even with the 15m thick of low velocity layer below the water bottom. This assumes that vector fidelity and coupling of the phones or nodes at the ocean bottom can be secured.

Significance of Subject Matter

With the recent advances of ocean bottom nodes (OBN) technologies, converted wave survey may have potential to solve for the obscured-zone imaging problems in Malaysia and other regions around the world.

Acknowledgement

We thank Robert Beham of Malaysia Business Unit and Brad Bankhead of Geophysical Technology at ConocoPhillips for supporting this project.
CFD Simulations and Experimental Validation of Sand Erosion on a Cylindrical Rod in Wet Gas Conditions
Authors: Wong C.Y. , Boulanger J. , Zamberi M.S.A. , Shaffee S.N.A. , Johar Z. , Jadid M.
Published: February 2015

The paper analyses original wet gas data from laboratory experiments and computational fluid dynamics (CFD) simulations. Air and water containing sand particles are transported in a vertical pipe and eventually impact on a centrally located aluminium rod. To determine the surface material loss over the rod surface, the surface profiles of the rod before and after the erosion test are accurately measured by a coordinate measurement machine. Three types of flow regimes with sand are examined and simulated, namely, water only, slug and annular flows.

The application of CFD as an engineering tool for assessment of sand erosion in field equipment is highlighted as well as the application of erosion intrusive well monitoring devices (e.g. ER probes) in wet gas conditions.

CFD simulation results predict the maximum depth loss in liquid only and annular regimes within 12%. In contrast, erosion caused by slug flows is under predicted by 2 orders of magnitude. The material loss is more focussed on the central location of the rod in the wet gas condition than it is in the annular flow case. The material loss in the liquid only case is more distributed over the rod than the annular case. Experimental results for all the flows show higher erosion loss on the cylindrical rod on the pipe centreline than closer to the pipe wall.

The work has identified important areas for improvement and further development in CFD techniques as they relate to sand erosion in field equipment.
One-Trip Fluid Activation and Filter Cake Break in One Step for Shape Memory Polymer Sand Control System
Authors: Garza Ramon , Liu Bairu , Sadana Anil
Published: February 2015

An innovative sand control technology is being developed that has the capability to totally conform to the wellbore and apply a positive stress on the formation face. This positive stress helps stabilize the formation, thereby preventing formation resorting. It is a shape memory polymer with the capability to change geometric shapes by heating above the glass transition temperature (Tg) or by chemically shifting its Tg. This shape memory polymeric material is molded to an initial geometric shape. The material is then heated and compacted to a smaller volume for run-in hole (RIH) geometry. As any shape memory polymer, it can recover its original shape if heated close to its Tg, or by chemically shifting its Tg to a new lower temperature that of its original Tg. This paper will present the results of additives added to completion fluids, giving the final fluid composition the ability to activate the polymer to its original shape, and simultaneously clean up the filter cake left by the drilling fluid before the polymer reaches the wellbore. The additives are delayed so the filter cake retains fluid loss properties during activation, but breaks shortly after the polymer reaches the gauge-hole there by allowing for production at maximum flow rates.
An Investigation on Factors Influencing In-Situ Emulsion Stability
Authors: W Razak Wan Nurul Adyani , Md Zain Zahidah , Zhang Yong  Sheng , Muthiah Chandramalar A V , Tusiman Fuziana , Hamdan Victor Hugo , Ohen Henry
Published: February 2015

An oil sample, collected from the wellhead of a shallow sand of a Malaysian reservoir, was identified as a very stable crude oil emulsion. This micro-emulsion type crude could not been separated in field separation facilities by gravity settling alone. The emulsion was very stable that it required either a high speed centrifuge (40,000 ppm) or high doses of emulsion breaker to be demulsified. Hence, from the perspective of field operational cost, it is critical to further investigate the factors that have potentially contributed to the stability of the crude oil emulsions.

The field of interest has been producing for over 30 years and its reservoir pressure has dropped to a level very close to the original bubble point pressure. All the wells in the field are gas lifted to enhance well productivity. Due to the unconsolidated nature of the reservoir rock, fines migration was one of contributing factor to formation damage. The reservoir crude was identified as biodegraded with missing of intermediate components from the reservoir fluid composition. As such, a structured bottom-hole sampling program was developed and bottom-hole samples were collected below gas lift mandrels while the gas lift was shut-in to thoroughly investigate the contributing factors to the formation of the crude emulsions and to identify the in-situ status of the crude.

Potential factors which could contribute to the formation of stable crude oil emulsions include 1) mixing of two or more incompatible crudes; 2) emulsifying agents including surface active materials (asphaltenes and resins, organic acids and bases, injected surfactants or oilfield chemicals) and finely divided solids (clay particles, sands, asphaltenes, wax, scale etc.). This study has investigated several potential contributing factors related to formation of the stable crude emulsions. It was concluded that naturally occurring fines could be the major contributing factor for the formation of the observed stable crude emulsion from the reservoir under study. Effect of gas lift on formation of the crude emulsion was found very minimal since the crude was at emulsion state even at reservoir depth.
Floating LNG is Coming of Age
Authors: Choi Michael S.
Published: February 2015

Global LNG trade is expected to more than double to more than 725 Mtpa by 2020. Some of the new projects will be developed with floating LNG (FLNG) technologies, perhaps even with a full floating LNG chain: FPSO for LNG production in the field, offshore LNG transfer to shuttle tankers, and floating receiving terminal that leads to the eventual gas distribution grid.

There are already many floating LNG receiving terminals operating successfully in the world. Now that construction has started on the Shell Prelude FLNG, floating LNG chain will finally be completed in 2016. Undoubtedly, more projects will follow. The economics of floating LNG is too compelling. Major cost savings can be achieved by: eliminating well head/production platform(s); processing platform to facilitate gas treating, liquids recovery and stabilization; FSO for condensate and NGL; gas compressor and pipeline to an LNG plant onshore; with a FLNG system located in the field. There are also the intangible cost savings such as efficiency gains by constructing the entire system in a ship yard, material and manpower logistics, and shorter project duration.

Many technologies have combined to make floating LNG chain a reality. Reliable subsea well and control systems have mitigated the risks of well operations. Proven glycol (MEG) and other regenerative hydrate management systems have allowed longer tie-back distance. Cost-effective mooring systems for large FPSO, flexible flowlines and catenary risers have enable floating system of FLNG size to be considered seriously. However, it is the advances in floating LNG technologies that have evolved over the past 25 years that finally tipped the risk-reward equation. Technologies such as offshore ship-to-ship transfer, motion tolerant processing and rotating equipment, LNG spill and gas safety, and deepwater cooling have matured to an acceptable stage.

This paper will present the economic drivers that make FLNG chain attractive to producers and buyers alike, and the many conventional production technologies and those unique to FLNG that combined to enable a FLNG chain to be developed in confidence. FLNG chain should be of especial interest to Southeast Asia which benefit both as a producer and a consumer of LNG.
Deepwater Hybrid Riser Systems
Authors: Luppi Ange , Cousin Gilles , O'Sullivan Robby
Published: February 2015

The future "Asia" deep water field developments will require new riser technologies to meet with the economical & operational demands, while ensuring safe and environmentally responsible applications.

The development of deep water oil & gas fields have motivated the need to develop new riser concepts (i.e. hybrid risers) in complement to the existing top tensioned risers, flexible or steel catenary risers.

The paper starts with a brief historical review of the "popular" Free Standing Hybrid Risers (FSHR) and the bundle Riser Towers (RT). Both riser concepts have been successfully installed in recent years; mainly in Angola, Nigeria, Brazil and Gulf of Mexico.

The Llatest evolution on hybrid riser designs will be also presented such as the Buoy Support Risers (BSR, Brazil), the Free Standing Flexible Riser (FSFR) and the Multi-Line Free Standing Risers (ML-FSR); the latter being a riser bundle to be fully assembled & installed offshore.

Application:

The paper will include the riser design methodology with references to industry codes & standards, recommended practices, etc. Typical functional loads and environmental load case matrix will be presented. Outline installation procedure of each riser system, including typical marine vessel spreads will be presented, e.g. for "Asia" installation fleet benchmarking and (future) availability review.

The Specific aspects of each technology readiness for "Asia" applications will be discussed, including the pros and cons of each system will be discussed.

Results, Observation, Conclusions:

The riser systems shall be designed for Asia "cyclone" conditions (e.g. 10 000 years wave return period) for both short term strength robustness verification and long term fatigue analyses.

Typical functional loads and environmental load case matrix will be presented.

Significance of Subject Matter:

Outline installation procedure of each riser system, including typical marine vessel spreads will be presented, e.g. for "Asia" installation fleet benchmarking and (future) availability review.

The future "Asia" deep water field developments will require new riser technologies to meet with the economical & operational demands, while ensuring safe and environmentally responsible applications.
Through Tubing Perforation Through 3 Barriers; Tubing Plus Two Casing
Authors: El Abdein Ossama Zein , B Yahia Zaidil
Published: February 2015

A brown field producing mainly from two main reservoirs, currently experiencing low reservoir pressures and high GOR ranging 400-1000 psig and 2000-20000 scf/stb respectively with about 17% average water cut. Re-perforation and adding new perforations are one of the key production enhancements activities for this field.

Two candidates were identified for additional perforation opportunities. Nodal analysis evaluation study based on reservoir parameters (permeability, water saturation, reservoir thickness) suggested oil can be gained by executing these opportunities.

The main issue in executing the perforation job was that the proposed perforation intervals are covered by 3 barriers which are the 2–3/8"tubing, 7" and 9-5/8" casing. Technical simulations and practical surface tests were performed to verify the integrity of the 2-3/8" tubing, and when shooting in multiple casings (7" Liner and 9-5/8" Casing). These tests were done to select the proper gun type, size and phasing (shot density) due to the limitation and risks associated with the through tubing perforation. The gun selected after the study was 1–11/16" strip gun with 2 SPF and 0 deg phasing.

The through tubing additional perforation jobs were executed with 20 ft and 135 ft for the two highly deviated (60-70 deg) candidate wells. These were the first job for PETRONAS Carigali in through tubing perforation through three barriers of tubing, liner and casing.

Very good results were achieved, where oil production increased by about 300 bopd and 200 bopd for the two wells respectively, and the WC% decreased from 45% to 0% for the first well due to higher reservoir pressure of the upper zone.

The successes of this application can enhance re-looking to many wells that have additional perforation ignored initially due to covering by tubing plus multiple casing which result in increasing oil production.

This paper shares the details of the well, the nodal analysis carried out to quantify the possible gain, the preparation for the yard tests and the evaluation in the gun selection.
New Design Method of Multi-Stage Hydraulic Fracturing in Shale Horizontal Well
Authors: Jianchun Guo , Bo Gou , Ting Yu , Jizheng Yi
Published: February 2015

In recent years, China has a rapid development of shale reservoirs. QianJiang lacustrine shale oil reservoirs in Jianghan Basin are similar to Bakken shale where Multi-stage hydraulic fractured horizontal wells have been proven to be an effective method for reservoir development. In this study, we propose a novel three-step design method for Multi-stage hydraulic fracturing. Firstly, feasibility study on the formation of fracture network was applied to Q2 well by the analysis of brittleness index, the difference of horizontal stresses and the characteristic of natural fissure. Meanwhile the suitable fracturing fluid system was selected and optimized. Then, the fracture network is treated as a high permeable zone. The number, volume and permeability of high permeable zone represent the stimulated reservoir volume and these parameters were optimized by numerical simulation. At last, optimization of treatment parameters (scale and perforation mode) were conducted by the relationship between fracture network parameters (number, volume and permeability) and treatment parameters.

We applied the new design method in the first shale oil horizontal Q2 well in Jianghan Basin. Evaluation of postfracture data indicated that the new design method was proper and easy to use.

The paper describes a new and convenient design method of multi-stage hydraulic fracturing in shale reservoirs. The lessons learned from fracturing in shale oil formation were also discussed. Finally, further information about stimulation of shale oil formation in Jianghan Basin was provided.
Optimisation of Autonomous Vehicles and Corresponding Docking Stations in Offshore Environment
Authors: Soofi Khalid A. , Lu Fang , Shu Zhichao , Hasenbein John , Morton David
Published: February 2015

This paper describes in detail an optimization model that provides a range of required number of autonomously operated vehicles (AUV and/or Drones) to monitor hazardous objects in offshore environment. In addition to the number of AUVs required it also calculates the number of docking stations required to service these AUVs. Finally, an attempt was made optimize the location of the docking stations. The paper will describe the general theory and an example application to monitor ice floes in offshore Arctic as described next.

Arctic offshore exploration and development is inherently complicated due to harsh environment caused by extreme cold temperatures as well as the sea ice environment. The sea ice floes are dynamic in nature and have variable spatial size, thickness, speed and directions. The modern satellite imagery (particularly Synthetic Aperture Radar with its all weather capability) provides a powerful tool to get the size, speed and direction of the floes. However the ice floe thickness is not readily discernible from satellite images and attempts to calculate the thickness directly from satellite imagery have yielded mixed results.

One method is to make use of Autonomous Underwater Vehicles (AUV) which can be equipped with upward looking sonar (either in single beam or a multi-beam mode) and then sent to hazardous sea ice floe on command. The idea is that AUV will then make all the required profiles of the ice floe underside providing concrete information about the thickness and then report back to the control center where a decision could be made whether we need to initiate an ice management response or not. If we are to use the AUV and ancillary docking stations to measure sea ice thickness then we need to know what is the suitable number of AUV and corresponding docking stations required for a near zero tolerance of failure (i.e. failed to detect a hazardous sea ice floe based on its thickness). We decided to solve this problem using a linear mixed-integer programming method.
Drilling Operations in HP/HT Environment
Authors: Ahmad Izhar , Akimov Oleg , Bond Paul , Cairns Paul , Gregg Thomas , Heimes Thomas , Russell Greig , Wiese Frank
Published: February 2015

The development of oil and gas assets is becoming more complex, with reserves being found in more challenging environments. Wells are being drilled to greater depths and in areas where the temperature gradient is higher. This has led to requirement for downhole equipment that can withstand temperature in excess of 302° F (150°C) and pressures in excess of 30,000 psi. Directional wells require measurement while drilling (MWD) and drilling systems that are reliable in these challenging environments. The problem with pressure is solved by seals to isolate equipment from the wellbore fluid and variations in materials and dimensions to withstand the pressure. The greater challenge is with electronic components in a high-temperature environment. Conventional drilling assemblies are generally rated to 302°F (150°C), which is far below the rating required for a high-temperature MWD and rotary steerable systems (RSS). New techniques were required in the design of MWD and RSS tools for high-temperature wells. This paper covers the work of one service company in the development of high-temperature drilling equipment that can be used in environments up to 350°F (175°C) and at pressures of 30,000 psi. The paper will describe the development of a new system that included an MWD system and an RSS capable of drilling wells at 350°F (175°C) and up to 30,000 psi. The authors will use detailed case histories to show how this system was used to provide a true step-change in performance in this challenging environment.
Successful Installation of a Completion System for Gas Migration Prevention
Authors: Pleasants Charles , Joseph Basil , Glynn John , Munshi Ammar , Knebel Mark
Published: February 2015

Completion systems will be presented for prevention of gas migration composed of an annular casing packer with remote-set technology activated by either an acoustic wave generator or casing wiper plug (CWP) with a magnetic array. Proven and reliable zero-extrusion gap element technology provides a gas-tight annular seal while reliability is enhanced by eliminating all communication ports and potential leak paths between the packer's ID and casing annulus. Design and qualification of these systems will be discussed along with the recent successful field installation of a shallow depth 18 5/8" × 24" system in a Sakhalin Island offshore well.

There are three main benefits of these systems. They provide a reliable mechanical barrier to flow after cementing which can result in a significant financial impact to the operators and their service providers. They eliminate issues with annular casing pressure (ACP) and sustained casing pressure (SCP). They also provide a permanent seal between casing strings that reduces risks of costly plug and abandonment (P&A) operations.

One system for shallow depth applications employs an acoustic wave generator at the rig floor to initiate the setting sequence upon completion of cementing operations. Another system activates the packer setting sequence with the CWP during cementing operations. An optional contingency setting sequence can be programmed prior to deployment and later deactivated if not required.

Industry standards are focused on reducing annular flow prior to, during, and after completion of primary cement jobs. While these changes will improve annular isolation, conventional cementing contains fundamental limitations that complicate control of shallow gas hazards and water flows. The above completion systems will help alleviate these concerns.
Validation and Verification of Large-Bore Tubing Retrievable Safety Valves for Gas Wells
Authors: Thompson Grant R.
Published: February 2015

This paper discusses validation and verification considerations for large-bore sub-surface safety valves, particularly with respect to use in natural gas completions producing high flow rates to 450 MMSCFD and beyond.

With natural gas wells, it is generally desirable from an economic standpoint to use larger production tubing than typically used for conventional oil wells. The larger sub-surface safety valves used in gas wells are exposed to unique conditions during operation. An estimate of the expected production rate of a given gas well is written into the statement of requirements for completion equipment. Validation and verification of the valve design to meet these requirements is a great challenge for equipment designers and test agencies, particularly for high flow rate analysis and testing. Only a small number of facilities have the capability to meet the volume and pressure requirements for testing the closure performance of large-bore safety valves against high gas flow rates.

Production gasses flowing through the tubing string encounter discontinuities in the form of stepped changes in diameter at each tubing connection. As these large-bore safety valves are in the full-open position, changes in the diameter from entry to exit are only slightly larger than those at the tubing connections. During closure, and especially closure while flowing, the transient state of the valve provides a significant discontinuity to the flow path in the immediate vicinity of the closure mechanism. Discussion of valve design utilizing various analysis models is provided to understand how these high rate flow characteristics affect valve performance.

In addition to unique analysis methods, these large-bore valves also require physical validation to ensure reliable performance in high gas flow rate conditions. Validation testing for these conditions is highly desirable and lends additional confidence in the performance of these products in emergency high flow rate scenarios. By including the proper design and testing protocols as shown in an actual case history, these large-bore valves capable of high flow rate applications are shown as fit for purpose in the most demanding of gas fields.
The Role of Seismic Inversion in Exploration and Development: Adding Value and Reducing Uncertainties
Authors: Rajput Sanjeev , Ring Michael
Published: February 2015

Developing accurate and high resolution reservoir models imply integration of data from different sources in varying scales, which is one of the major challenges in reservoir characterization. Relatively low resolution of seismic data could only offer a structural model for the reservoir but its availability and areal coverage suggests that it has valuable information to constrain the reservoir model. This information could be extracted by the process of seismic inversion that transforms seismic data into a quantitative rock property, descriptive of the reservoir. In this study a novel intelligent seismic inversion workflow is presented to achieve a desirable correlation between low-frequency seismic signals, and the much higher frequency well log data with reducing uncertainties.

The proposed logical workflow consists of a systematic progression from well data analysis to rock physics modelling to seismic inversion and finally reservoir property estimation. The results reveals that optimization of seismic inversion workflow must be handled in unique manner. By using a series of simple examples to complicated case histories it will be demonstrated that significant benefits can be obtained by following an optimized workflow that is tailored to deal with the uncertainties that impact the end product.

It can be concluded that relative inversion should be performed first so that one should be crystal clear about what information can be extracted only from the seismic without bias from logs. The next step is absolute inversion which implies logs as geologic context and broadens the inversion band to establish the relation between log and seismic. At final stage one should consider more advanced techniques such as model base inversion, elastic inversion, simultaneous and geostatistical inversion. The ultimate goal is optimum reservoir characterization and management which leads to success and reduce uncertainties.
Permeability-Dependent Retention of Polymer in Heterogeneous Reservoirs
Authors: Choi B. , Lee K.S. , Yu K.
Published: February 2015

Polymer retention occurring in porous media induces significant mobility reduction as well as poor sweep efficiency. In the heterogeneous reservoir, it is very complicated and difficult to analyze performance of polymer due to permeability-dependent retention. Among various mechanisms of retention, mechanical entrapment of polymer affects mainly the propagation of injected polymer solution by forming macromolecular polymer plugging into pore throats, especially occurring in low permeability zone. Besides, polymer adsorption contributes to mobility reduction and polymer retention. The influence of heterogeneity on polymer retention has been not investigated accurately in the reservoir scale and limited to experimental studies, even though both mechanisms are highly dependent on permeability. In this paper, extensive numerical simulations incorporating mathematical modeling on the retention mechanisms have been performed to examine polymer propagation and flow behavior at various heterogeneous reservoir models. All reservoir models have same average permeability and different Dykstra-Parsons' coefficients (VDP) to represent wide range of reservoir heterogeneity.

The results show the amount of polymer adsorption is at high level in low permeability zone. The mechanical entrapment also exhibits same trend with adsorption. Most of polymer retention is accumulated in the low permeability zone, which causes a substantial increase resistance factor in the area. After polymer flooding, total amount of polymer accumulated by retention in the reservoir with VDP=0.72 is 2.5 times more than that of homogeneous reservoir. Furthermore, flow path of polymer solution is restricted to only high permeability zone in the highly heterogeneous reservoir. Thus, the polymer propagates through small pores at a lower rate, giving very poor sweep and irregular propagation path. Sweep efficiency of polymer flooding in the case of VDP=0.72 is reduced about 33% compared to the case of VDP=0.14. This paper could be helpful for an accurate assessment of polymer retention during polymer floods in the heterogeneous reservoirs.
Comprehensive Rigsite Operations Surveillance for Better Drilling Efficiency
Authors: Mohamad Azlan , Mad Desa M Latif , Ismail Zulhilmi M. , Hj. Abu Talib Hj. Sa'aid Hazley , Kardani Ilen , Deshamduli Dintho , Rosli Azlesham , Hj. Salleh Intan Hairunissa
Published: February 2015

Implementing total operational surveillance can provide a detailed statistical breakdown of each rig's activities within an operation, enabling operators to accurately measure operational efficiency and flagging potential downtime events. PETRONAS has embarked on a full scale rigsite since 2010 with the setting up of a comprehensive operations surveillance monitoring center (Smart DOMC). This paper describes the process and benefits of streaming down rigsite operational information and data on a real-time basis to the monitoring center.

The Smart DOMC has become a center of excellence for domestic knowledge sharing, exchanging information, as well as a database of best practices, systematic trouble shooting, applied technologies, and capturing lessons learned. Very soon, the Smart DOMC will monitor all PETRONAS Carigali operations worldwide, which will encompass almost all drilling operations including land jobs, offshore operations, deep water, high pressure/high-temperature (HP/HT), carbonate drilling and unconventional technologies. These complex operations must be monitored and supported with robust infrastructures and competent manpower within the monitoring center.

Operationally, high-resolution tools and sensors (surface and downhole) must be installed at the rig site for automatic data generation and transfer to the Smart DOMC by means of satellite. This information is segregated to produce reports related to wellbore integrity, formation evaluation, bottom hole assembly (BHA) performance, and drilling efficiency. Proprietary software is then used to transform digital data into presentable graphical formats for further evaluation and data storage.

Implementation of such engineering and data surveillance were implemented in recent drilling campaigns in the Angsi Field, Sumandak, Tangga Barat, and Sepat projects. USD millions were saved by eliminating potential non-productive time (NPT) events and implementing efficient decision making. Obtaining accurate statistical data from each rig's operations allowed drilling management to reduce the NPT to barely minimum i.e., less than 5%.
Using LWD Tools during Soil Boring Operation to Identify Offshore Geohazards
Authors: Kardani Ilen , Askar Mohd Azlan Shah , Bong Martin , Sidek Rosli , B Mokhtaza M. Haflan B , Muhamad Zakaria B , B Zubir Ahmad Bakri , Yun Thiam Yap
Published: February 2015

Logging While Drilling (LWD) tools have been used in most drilling operations whether offshore or onshore, and from top holes all the way to total depth. This practice provides most of the information required for all stake holders of oil and gas reservoirs. The focus of this paper will be the use of LWD tools in soil boring operations which has never been done or recorded before.

Site investigation is the first step in gathering geotechnical information for evaluating soil integrity for activities such as pipeline installation, platform construction, jacket installation, or drilling rig positioning. A feasibility study is done by performing a series of in-situ (or lab) tests to help operators and drilling contractors identify any geohazards and prepare suitable mitigation plans. Failure to do so can lead to expensive incidents during subsequent operations such as shallow gas, jackup rig punch through, damage on the jacket, pipeline failures, shallow water flow, gas hydrates, and environmental pollution.

LWD tools in combination with standard soil boring investigation (coring, soil sampling, cone penetration test, etc.) provide comprehensive site survey information including rock types, gas identification, wellbore imaging, water saturation, shear measurement, wellbore stability, lithology, and fracture identification. More detailed information can be acquired by using nuclear tools or seismic while drilling but these are not recommended for soil boring operations. In addition, the operator will have continuous formation evaluation data in cases where the surface hole is driven by conductor pipe. (LWD tools cannot acquire data once the casing is set.)

Combining petrophysical, geophysical, and geotechnical data at the earliest stage lets operators prevent undesired events by clearly identifying geohazards, and then either mitigating the hazards or determining that the location is unsuitable for further operations.