bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Initial Condition of Fracture Surfaces, Acid Spending and Acid Type on Conductivity of Acid Fracture
Authors: Al-Momin Ali , Zhu D. , Hill A.D.
Published: February 2015

Predicating the conductivity of acid fracture is not possible using analytical or numerical models due to stochastic nature of acid reaction with rock and complex leak-off behavior of acid. Other alternatives are either empirical correlations or conducting experiments mimicking field treatments.

We adopted experimental approach considering scaling down of field conditions to laboratory scale by matching Reynold's number to represents flow along the facture and acid leak-off through fracture faces, and Pecelt number to represent acid transport to fracture walls. Experiments conducted comprise three stages: dynamic etching, surface characterization of etched cores and conductivity measurement.

One objective of this work is to understand mechanism through which conductivity is generated in acid fracturing treatment. Moreover, the effect of initial condition of fracture surfaces on conductivity was investigated to quantify the difference between rough-walled and smooth-walled fractures. Another area of interest is the variation of conductivity along the fracture due to acid spending. In previous works, experiments only represented fracture entrance of actual treatment neglecting that acid is spent along the fracture which affects conductivity. Therefore, to better predicate the performance of an acid fracture, experiments at different acid concentrations representing different positions along the fracture were conducted. We also investigate effect of contact time, acid system type and treatment temperature on conductivity using San Andres Dolomite cores.

Preliminary results showed that initial condition of fracture surface has a major influence on fracture conductivity where rough-walled fracture predicted higher conductivity by almost an order of magnitude compared to smooth-walled. And mechanism through which conductivity created is by smoothing peaks and valleys creating surfaces mismatch rather than creating asperities. Furthermore, results showed that acid spending does not necessarily cause a decrease in conductivity from entrance toward the tip of a fracture. Also, cross-linked acid is more effective in terms of dissolving rock and controlling fluid leak-off compared to linear gelled acid. Furthermore, more etching does not always translate to higher conductivity suggesting the existence of optimum contact time.

Results obtained provide new insights to better understand and predicate conductivity of acid fracture and suggest guidelines to optimize treatment design.
Insights into a New Super-Giant Gas Field - Sedimentology and Reservoir Modeling of the Coral Reservoir Complex, Offshore Northern Mozambique
Authors: Palermo Denis , Galbiati Mauro , Famiglietti Massimo , Marchesini Marco , Mezzapesa Domenico , Fonnesu Franco
Published: February 2015

The super giant Mamba field is located in the Area 4 deep water block, offshore northern Mozambique. Hosting over 80 TCF of natural gas, the Tertiary reservoir complex will supply a new LNG plant. The Coral reservoir represents the Lower Eocene reservoir unit of the Mamba Complex, which is formed by turbidite channel and lobe deposits of several deepwater basin floor fan accumulations. Generally, the coarse and massive reservoir sandstones are extraordinarily thick, clean and homogeneous compared to other deep water plays, e.g. GOM, West Africa. High quality 3D seismic and data from three wells, including 144m core, indicate that the excellent reservoir quality of the Mamba complex can be related to the presence of strong, deep water bottom currents that influenced the deposition of gravity-flows. An integrated sedimentological approach on multiple scales, which comprises detailed sedimentological core descriptions, seismic stratigraphy and seismic attribute analysis, provides new insights into the depositional processes and the reservoir architecture of a fascinating deepwater play. The depositional model suggests Lower Eocene bottom crossing the sand rich gravity flows perpendicularly. This results in significant flow-stripping and deviation of the turbulent, fine-grained suspension cloud. The process accumulates the greatest amount of fines on the leeward part of the channel complex and creates unilateral drift-mounds instead of bi-lateral levee complexes. This leads to relatively mud-free facies types and a characteristic low angle offset stacking of the amalgamated channel complexes. However, dependent on associated flow-velocities and grain sizes, also the depositional lobes show exceptionally good reservoir properties, characteristic geometries and stacking patterns. The integrated and process-oriented approach allowed detailed mapping and modeling of the reservoir bodies, which permits prediction of reservoir quality and optimization of the field development.
Integrated Optimisation for Surface and Sub Surface Towards Maximising Production
Authors: B Zainal Abidin Shahrul Azman , Bt Hussein Noorhidayah
Published: February 2015

Conventionally a standalone topside process model can only achieve production increment of up to 1%. In order to achieve higher production increment, an integrated topside process and subsurface model is required. This modeling technique requires the integration of different modeling platforms for reservoir, wells, headers, topside facility, interconnecting pipelines between platforms and re-injection wells back to the reservoir. The main challenge is to develop a seamless interface communication between the different modeling platforms.

PETRONAS has developed the link and global optimization engine to achieve seamless communication between the various Integrated Optimization tools such as PROSPER, GAP, and OLGA and iCON for steady-state and dynamic environment through parametric run approach. This allows faster diagnostic and effective decisions making in determining the topside optimum operating conditions.

To date, this integrated surface and subsurface optimization approach has realized up to 5% production increase from several platforms in Sarawak Operations. This paper also discusses the current and future application of the integrated approach for PETRONAS Carigali Integrated Transient Network Modeling (ITNM) and Integrated Operation (IO) projects.
Innovative Bit Design Coupled with New Cutter Technology Improves PDC Bit Performance in Challenging Changbei Gas Field Application
Authors: Yan Li , Shan Xun , Seng Yeong Soon , Suresh Kottapurath , Ningbo Wang , Jianping Wang , Hongliang Zhang , Peng Li , Lu Zhang
Published: February 2015

Changbei is a marginal tight-gas field in Yulin, west China. Because of high drilling costs associated with the Changbei gas field, operators focus on improving drilling performance by means of reducing drilling and tripping times. One effective way to maximize drilling efficiency is proper bit selection. This paper presents an improved bit design and successful field results from two representative sections: CB 17–2 and CB18–2, both 12.25-in. sections. Both applications were characterized by a 2500-m long directional section, usually drilled through varying formations ranging from soft abrasive to very hard, with compressive strength ranging from 7 to 20 kpsi. Three main challenges were encountered during this operation. First, when drilling the upper portion of the sections, a series of transitional hard/soft formations, such as abrasive sandstone/siltstone and claystone, were encountered, which generated extensive vibrations and decreased the rate of penetration (ROP). Secondly, the long soft claystone intervals and frequent thin but very abrasive sandstone stringers in the lower part of the section not only increased bit balling potential, but also created premature cutter wear and loss of aggressiveness. The third challenge using a polycrystalline diamond compact (PDC) bit in this area related to drilling the whole section in fewer trips and maximizing the ROP to reduce drilling costs. To overcome these challenges, extensive geological research was performed within the 12.25-in. section of the Changbei gas field. Then, an improved bit design proposal was implemented, which consisted of three aspects:apply new cutter technology to the bits,optimize the bit design based on directional and formation challenges, anddevelop optimum drilling parameters. Based on field results, this approach set both ROP and interval records compared to offsets and helped the operator save 3.26 drilling days_one trip and one bottomhole assembly (BHA) in Section CB17–2. Drilling efficiency for both sections was enhanced by more than 20% compared to offset wells. Furthermore, for both sections, the bit used exhibited improved dull conditions compared to offsets.
FPSOS for Deepwater Applications
Authors: Su Zhiyong , Luo Yong , Qi Xiaoliang , Xie Yi
Published: February 2015

This paper addresses the design and challenges of FPSOs for deepwater applications. The building blocks of FPSOs of topsides, hull, turret, mooring and risers are reviewed and a design concept of FPSO for deepwater application in the South China Sea is configured. Especially, the turret configuration of the deepwater FPSO is proposed. Engineering analysis with regards to the system global performance, Turret loads design, mooring and riser designs and their impact to the turret and hull is conducted. The technical challenges facing the deepwater FPSO design in areas of turret loads, mooring and riser design, coupling effects between FPSO and moorings/risers are highlighted. In the deepwater application, the single point mooring system and the riser system design for the FPSO become the key issues in the project because both systems have to face new challenges, such as deep water depth, wild environments and high fluid pressure.

A case study of a specific FPSO design in 1500m water depth in the South China Sea environment is then presented. The paper concludes that even though the design of the deepwater FPSO in harsh environment conditions can be technically challenging, the FPSO concept is a versatile solution for the deepwater applications in the South China Sea.
The History of Hydrocarbon-Based Ultrafine Cement Slurry System for Water Shutoff in Offshore Mexico
Authors: Deolarte Carlos , Zepeda Rafael , Cancino Victor , Robles Fernando , Soriano Eduardo
Published: February 2015

Excessive water production can detrimentally affect the profitability of hydrocarbon producing wells if not controlled properly. Water cut present in the oil stream coming from the wells producing in several of the offshore Mexico fields is an issue of critical importance because oil production is sent to exportation. In the beginning the operators didn't have water handling facilities, forcing operators to monitor wells with water cut as low as 60.0 %. Forced to control by decreasing the choke size, in some cases the operator can handle the water, but in many cases required shutting the well in completely causing a negative impact on the production of the fields. Two of the main drivers of excessive water production is the mature fields are the influx of water behind the casing and/or water flowing through the natural fractures of these carbonate reservoirs. This paper describes the best practices of using a selective hydrocarbon-based ultra-fine cement (UFC) slurry system to slow down water production in offshore Mexico wells.

The UFC slurry consists of ultra-fine cement with an average particle size of 2.5 μm, a surfactant, and a hydrocarbon carrier fluid (i.e. diesel). Because the slurry is hydrocarbon-based, it remains inactive when contacting an oil-producing zone. When the system contacts a water producing zone the slurry will remain mobile for an additional 20 to 30 minutes before beginning to set. The delayed setting of the cement slurry is ideal for placing the ultrafine cement slurry into water-bearing formation fractures some distance away from the wellbore. The slurry is designed to selectively shut off water flowing into the wellbore and is applicable up to 400°F (204°C).

This paper describes the successful best practices and mistakes of the implementation of the UFC slurry system in Offshore Mexico to seal off unwanted water flowing through natural fractures and/or behind the casing. A variety of case histories will be discussed in detail along with post-production numbers after the treatment. Up to date, more 100 UFC treatments have been performed in Southern Mexico
Concept Proofing of Supersonic Nozzle Separator for CO2 Separation from Natural Gas using a Flow Loop
Authors: Ahmad Samawe R. , Rostani K. , Mohd Jalil A. , Esa M. , Othman N.
Published: February 2015

Application of nozzle supersonic expansion has been used for dehydration and hydrocarbon dew pointing. Recently, the potential of the supersonic expansion technology in bulk CO2 separation from natural gas has been studied. The proof of concept testing of the nozzle prototype is being validated via a 15 MMSCFD flow loop at 36 bar and -19°C at KEMA, Groningen. The setup consists of a multiphase pump, gas-liquid separators and heat exchangers. Pressure transducer has been installed along the nozzle tube prototype and the pressure reading is recorded through the data acquisition system. Besides pressure, the temperature inlet, primary and secondary outlet of the tube has been monitored. Two vibration sensors have been installed to monitor the effect of the high vibration to the prototype. For quality check, an on-line gas chromatography has been installed at the inlet and the outlet. Several challenges had been faced during the start-up of the test in order to achieve the test condition. The pressure profile plotted along the prototype will be compared with the CFD simulation with various parameters evaluated. The shockwave predicted via simulation has been observed at the pressure profile and significant flow of liquid CO2 has been produced during the initial test. Reduction of temperature at the outlet of the tube gives an indication of separation has been occurred in the process. The preliminary results from the experiment will provide the improvements for the CFD simulation numerical modelling as well as the in-house coding for CO2 separation efficiency.
Maintaining Wellbore Integrity in Steam Injection Wells Using Fit for Purpose Cement Systems in Oman
Authors: Jain Bipin , Khattak Mohammad Arif , Mesa Alvaro Martin , Al Kalbani Sultan , Ahmed Junaid , Al Aghbari Salim , Qassabi Nabhan
Published: February 2015

In Oman, certain fields contain heavy oil and recovery of this oil is done through steam injection, which leads to rapid heat-up of the cemented annulus to very high temperatures. Throughout the lifecycle of steam injection wells, stresses in the cement sheath induced by rapid temperature cycling, results in mechanical damage and ultimate failure of the cement sheath. Such failure leads to loss of steam down-hole and an increased amount of steam is required to extract the oil. This translates into higher energy costs for steam production. In extreme cases steam can be seen breaking through to the surface.

In Oman heavy oil reserves are found in naturally fractured limestone formations prone to severe losses while drilling. To ensure proper cement placement, systems with densities below 1,400 kg/m3 are required. In the past certain wells were cemented using foam cements with density close to that of water. Data collected from earlier steam injection drilling campaigns by PDO suggests that maintaining cement integrity is a key challenge. The issue is related to initially not being able to place the cement properly due to losses and subsequent degradation of set cement as it does not withstand the stresses created during steam injection process.

A recently developed specialized cement system was used to successfully cement one such well. The system was placed successfully using fibers based pill ahead of the slurry to cure the losses. Stresses created on the cement sheath during steam injection were simulated, mechanical and thermal properties of the cement system were optimized to prevent failure, and evaluation was performed for wellbore integrity. Excellent mechanical and thermal properties for a 1,400 kg/m3 slurry system showed no breakthrough of steam when exposed to multiple temperature cycles of up to 300 degC. Multiple wells in Oman have been cemented using this technology.

The current paper looks at various aspects of design, execution and evaluation of such cement systems.
Kinetic Hydrate Inhibition Performance of MEG in Under-Inhibition System: Reduction Opportunities of MEG Injection for Offshore Gas Field Developments
Authors: Kim Jakyung , Shin Kyuchul , Kim Juneyoung , Chang Daejun , Seo Yutaek , Chang Kwang Pil
Published: February 2015

In offshore gas field development, mono-ethylene glycol (MEG) has been a robust choice for hydrate inhibition in subsea production systems and flowlines. Once hydrate blockage forms, considerable efforts and loss of production are inevitable to remediate the hydrate blockage. Therefore, the industry has been relying on the injection of considerable amount of MEG which is used to be over-estimated based on the worst operation condition: shut-in pressure, sea water temperature, and maximum water cut. However, during steady-state operation, the range of operation condition might be different from the worst condition and for shut-in condition; the sufficient cool down time for hydrate formation could be guaranteed with appropriate insulation. More thorough analysis is required using the multiphase flow simulator. Furthermore, recent studies suggest that MEG may have kinetic hydrate inhibition (KHI) performance. An under-inhibited system where an insufficient amount of THI is present might be possible to avoid hydrate blockage issues and to reduce the operating cost for the injection of large amount of MEG.

In this work, the evaluation of under-inhibited system is carried out to identify the possibility of hydrate blockage formation using multiphase flow simulation tool, OLGA, and accompanying hydrate kinetics experiments. The temperature and pressure profiles along with the liquid holdup are estimated during the steady-state and transient operation of offshore gas fields. The optimized concentration of MEG is calculated form the simulation results. Then the under-inhibition concept is evaluated from hydrate kinetics experiments to investigate possible reduction of MEG injection rate. The obtained results suggest that at least 30% of MEG injection can be reduced using the kinetic inhibition performance of MEG in under-inhibited system, which in turn increase economic feasibility of offshore gas fields. More advanced strategy to manage hydrate blockage in offshore field developments would be developed based on the optimization of the injection rate in under-inhibited system.
Numerical Analysis on the Interaction between Two Zipper Frac Wells Using the Continuum Damage Method
Authors: Shen Xinpu
Published: February 2015

Description

A numerical simulation has been performed on the formation fracturing process under hydraulic stimulation. The Continuum Damage method has been used for modeling of formations fractures. A coupled calculation of hydro-mechanical problem using the three-dimensional (3D) finite-element method (FEM) is also introduced.

Application

This model was used to estimate the results of a zipper-frac design from stimulation measurements of two horizontal wells in a tight-sand field.

Results, Observations, and Conclusions

The parameter calibration of the continuum damage model used here was performed with measured micro-seismic data of fracture propagation under injection stimulation obtained from an offset well. The initial damage value was assigned to the formation before injection stimulation simulation to model the effect of natural fractures. With a given geometry (100 m width, 100 m length, and 20 m thickness), which has two injection sections, damage evolution was calculated under a given value of injection fluid flow rate. The model is made simple as a result of geometrical symmetry.

Numerical results of the 3D-coupled hydro-mechanical problem are presented, which include:damage distribution between two injection stages after stimulation. The value of the continuum damage variable here represents both natural and induced fractures around a horizontal injection well for a specific injection pressure;The distribution of pore pressure and maximum principal strain components are analyzed and shown;damage variable develops in a similar pattern to that of maximum principal strain;comparison of damage distribution and stimulated formation volume for two different injection measurements.

Significance

This work shows that interaction between two neighboring stimulation stages can increase the effective fracture length by overlapping the front area of the damage zones. This work shows that the coupled hydro-mechanical finite-element model is an effective tool for estimating stimulated volume in tight sand reservoirs.
Remote Control Systems Advance Offshore EPRS
Authors: Lim George
Published: February 2015

Description of the Material

Integrity management programs are used to prevent, detect and mitigate integrity threats that occur throughout a pipeline's lifecycle, from construction through operation to decommissioning. But unfortunate events occur, causing pipeline failures that jeopardize people, the environment and business. Offshore operators often establish a dedicated Emergency Pipeline Repair System (EPRS) to effectively respond to - and recover from - an incident. This paper describes several remote control systems that contribute to EPRS capacity.

Application

Attributes of an effective EPRS include its ability to cover 1) all incidents, by having a comprehensive inventory of the right tools, 2) the full lifecycle of pipeline assets, from design to decommissioning, and 3) all operating areas, including deep water or where unsafe diver conditions exist.

Results, Observations and Conclusions

T.D. Williamson (TDW) has developed several remote-controlled tools that may assist in establishing optimum response capacity. Inserted in the pipeline in strategic positions along the suspended section during pipe laying, the SmartLay™ tool acts as instantaneous barrier against flooding in case of an inadvertent wet buckle, protecting the vessel from undue forces from the heavier flooded pipe and preventing costly and time consuming dewatering and re-commissioning of the just-laid pipeline. The Clamp Installation Tool (CIT) is a lightweight, readily deployable tool run with standard work class ROVs for the installation of any size repair clamps or hot tap tees from any third party supplier. Combined with the CIT for tee installation, the remote-controlled Subsea 1200RC Tapping Machine offers a hot tap solution that not only facilitates deep water repairs, but also reduces risk to personnel and increases efficiency. The SmartPlug® tool is an un-tethered inline tool for isolation management of a range of repair scenarios where intrusive plugging is less desirable. It is remotely controlled via thru-the-wall communication by SmartTrack™ technology, which can also act as stand-alone pig tracking equipment.

Significance of Subject Matter

The anti-flooding SmartLay™ Tool can cover the construction phase; the Subsea 1200RC Tapping Machine and Clamp Installation Tool assist deep water intervention and repair during operations; SmartPlug® technology offers isolation management; and SmartTrack™ pig tracking affords integrity management.
Composite Abrasive Technology: A Key Part of New Sustainable Commissioning & Process
Authors: do Nascimento Bernardino Nilton , Ramli Mazrin
Published: February 2015

In what isbeing called the first Oil and Gas "Sustainable Commissioning" project, advanced composite abrasives (ACAs) is beingused to help conserve precious resources. A recent field study and projectconducted by Odebrechtcommissioning manager, Bernardino Nilton do Nascimento revealed key points thathave already saved water in a region with unprecedented pressure to conserve. The core ofthis sustainable solution includes ACAs and a "pig" system, which were firstfield tested then used in Petrobras Refinaria Abreu de Lima (Brasil). Theproject entailed blast-cleaning cooling lines, hydrostatic testing and thennon-destructive testing in their TR-86 (Unity 32) Cooling Tower. Typically, residual products are removed (1) toassure efficient flow though refinerysystems and (2) to protect operating equipment. A rinsingsolution is passed through all pipes and then to a water treatment station. Testresults provided groundbreaking observations for Nascimento and PetrobrasProject Manager, Ricardo dos Santos Ramos:No water was used during ACA blasting it was concluded that 200,000 liters (or53,000 gallons) of water was saved on Unity 32 Cooling Tower alone.Water-relatedsteps (e.g. conditioning, special treatment, disposal anddisposal) were eliminated.Cleaningoperations on commissioning projects would have included seven steps:waterconditioning,water washing,chemical rinsing,drying,applyinglining/pipe treatment,water treatmentdisposal.

During ACAblasting, the number of steps dropped to two? (1) blasting pipe internals(2) applying the appropriate treatment via pig.

Nascimentoand Ramos extrapolated savings of 16 million liters (4.3 million gallons) ofwater by using ACA for all refinery line cleaning during the commissioning.

Withtesting and the first lines completed, Nascimento and Ramos then proceeded toother parts of the refinery commissioning project, continuing to usedust-suppressing ACA technology. They also found that sensitive equipment likecompressors and pumps had added reliability. This paperwill outline field testing and project data, comparing common cleaningoperations to the "Sustainable Commissioning" process. Results will convey environmental and economic significance and the carryoverto similar offshore applications - during commissioning and maintenance of internalpiping systems.
Subsea Development of Marginal Deepwater Fields
Authors: Samad J.
Published: February 2015

Development of greenfield deep water oil and gas fields are generally known to be expensive, compared with conventional shallow water fields development. Having marginal fields in deep water only compounds the challenge to development.

This presentation aims to discuss the challenges associated with developing marginal gas fields in deep water. It however centers primarily on the subsea portion of the development.

Marginal gas fields are typically < 500 bcf, and are best developed when there is an opportunity to combine a number of such marginal fields for a clustered development. However, invariably, each field has different characteristics (volume, pressure, composition) and hence requires careful planning to ensure constant flow to production facilities.

The presentation will thus elaborate on the use of software tools such as Maximus for phased field development planning to ensure base load gas production throughout the project lifetime.

At FEED stage, the subsea facilities and topsides facilities are typically carried out by separate design contractors, involving an interface at the surface that needs to be managed well to ensure optimum overall system design for smooth economical operation.

In the case of developments utilising FLNG the interface issues can become rather complicated when the subsea facilities design team at FEED stage has to interface with multiple FLNG FEED contractors participating in a design competition.

The challenges centred round the subsea development include Field Layout planning, FPF interfaces, subsea CAPEX, Flow Assurance, Hardware limitations (qualification), Technology (applications of dual directional subsea wyes, and subsea pigging launcher/receivers). The presentation will also elaborate on the use of other software tools such as ArcGIS for pipeline route layout planning and optimisation, and Star-CCM Plus for sand erosion CFD (Computational Fluid Dynamics) modeling.
Interval Pressure Transient Test and Stress Testing in Coal Bed Methane Using Dual Packer Formation Testers: Case Studies from Indonesia
Authors: Weatherall Glyn , Halinda Debby , Daungkaew Saifon , Suriyanto Olivia , Mas Cholid , Islam Anzar
Published: February 2015

Significance of Subject Matter

Coal Bed Methane (CBM) has become one of the most important unconventional resources for today petroleum industry since its discovery in many countries including Indonesia. The main challenge for CBM fields is a proper reservoir characterization in coal matrix, cleat and shale layers. Another main challenge is a variation in reservoir productivity from zone to zone. Formation evaluation for this unconventional reservoir is not as straight forward because the evaluation program needs to be adjusted to obtain enough reservoir information for an effective field development plan.

Application

The Dual Packer Formation Testers (FT) can be used to test zones where matrix porosity is too low for a single probe FT such as carbonate and fracture basement reservoirs. However, the use of dual packer FT remains quite a challenge due to time per station, tool sticking risk, and limited packer intervals. This paper reviews the use of Dual Packer FT to evaluate reservoir properties in one of the CBM wells in Asia.

Description of the material

This paper presents the use of Dual Packer FT for an Interval Pressure Transient Test (IPTT) for reservoir pressure, fluid sampling, zone permeability, and also for a stress testing applications. This paper will be more focused on the stress testing technique using Dual Packer FT. This "micro-frac" application in CBM wells plays an important role in providing shale layers' stress parameters such as a fracture treatment design and an optimal completion design. However, it also has its operational challenges associated for pre-job planning.

Results, Observations, and Conclusions

This paper presents a systematic integration between pressure transient analysis and fracture diagnostic plots utilizing a G-function plot, as well as a Square-Root time plot in this smaller scale of fracturing operations. The output of the analysis including initial breakdown pressure, closure pressure, fracture propagation pressure, initial shut-in pressure, and shale permeability will be discussed and compared with full scale fracturing, drilling leak off tests, and modeling results from geomechanics study. This paper will also address technical and operational aspects of the Dual Packer FT operation in this unconventional reserve.
Development of a PDC-Tricone Hybrid Technology to Solve Drilling Problems of Surface Holes in North Africa
Authors: Moujbani Walid , Aliko Enis , Chaabane Naceur
Published: February 2015

A major oil company started a drilling campaign onshore South Tunisia, where wells require long, 16-in. diameter surface holes to be drilled through a variety of lithologies that present several drilling challenges..

The challenges in this section start with mud losses that usually require controlled rate of penetration (ROP) to manage the volume of cuttings. The second drilling challenge comes while drilling through clays, which can cause balling of the bit and stabilisers. The third and most difficult drilling challenge is presented when Pyrite and sometimes Chert nodules are encountered..

To overcome these challenges, a novel PDC-Tricone hybrid bit technology was designed and tested as a potential solution. The bit's combined cutting structure can drill with the efficiency and aggressiveness of a PDC bit and handle a hard nodular formation like a Tricone bit, without suffering any damage. The bit enabled the operator to drill the entire section in a single run and saved more than 55,000 USD on the first well. Following this run, the bit was modified to increase its aggressiveness and durability and was run in more wells, confirming the initial success..

As the operator and the service company became more confident that the hybrid bit could drill the entire section without suffering damage, the operating parameters were raised to gain higher ROP. Additional improvements were made to adapt to the more demanding conditions, and the PDC-Tricone hybrid bit matched the performance of conventional PDC bits, generating financial gains for the operator..

Based on the success of this campaign, the same bit type was proposed to other operators, drilling offshore Morocco, with the ambitious objective of drilling a long chert-bearing section in one run.. This paper describes the development of the PDC-Tricone hybrid bit design, the results of lab testing conducted during this development, design iterations, and the results of its application in North Africa. Details performance compared to conventional PDC bits and results of offshore applications will be also presented.
Reliable Lashing Lines Fatigue Monitoring for a Tender-Assisted Drilling Unit
Authors: Prislin Igor , Chabot Luc , Dean Linda H. , Liu Tuanjie , Ye Wei
Published: February 2015

Description of the Proposed Paper:

The paper describes a reliable, effective, and practical, solution for monitoring and reporting fatigue damage of lashing lines on the Murphy Kikeh DTU. The solution is based on a ton-cycle method that uses measured line tension and calculated number of cycles when the critical line segment enters and exits the sheave. The method is calibrated using real data and then implemented on-board of the DTU. It provides indication of the integrity endurance level of a critical lashing line. The same method helped in re-designing the original lashing system, which reduced wear and prolonged the fatigue life by a factor of four.

Application:

The integrity and the fatigue life of the lashing lines that keep TAD unit closely connected to the DTU is carefully and continuously monitored by the Integrated Marine Monitoring System.

Fatigue life of a line is monitored through cumulative ton-cycle value. When this value approaches the calibrated threshold, the line can be replaced at the most convenient time, avoiding unpleasant surprises such as when a line breaks during production, making the production safer and more cost effective.

Results, Observations, and Conclusions:

The lashing line ton-cycle method has been integrated with the other marine and structural monitoring parameters on board of the Kike DTU for several years.. When the values approach the 100% of the absorbed fatigue life, the results are displayed on the operator screens in the control room indicating that the line is in a critical condition with a high expectation to break. This indication helps the operator to plan, prepare and conduct the line maintenance or replacement in a timely manner and at the most convenient time without interrupting critical phases of operation. This process became a standard process for the lashing line integrity monitoring and maintenance and it has been working reliably for more than three years.

Significance of Subject Matter:

Developed and implemented ton-cycle method shows a simple yet effective and reliable method for increasing overall the safety of operations, as well as preventing costly interruption of normal production on the Kikeh DTU and the nearby TAD unit.
Pipe End Round Forming Equipment and Control System - The Fundamental Solution for Reducing Welding Defects in Offshore Pipeline Constructions -
Authors: Kishiguchi Tetsuya , Hosada Hiroyuki , Ikuno Yasuyukiy , Ikezaki Toru , Akasaka Masayoshi , Torii Tadashi
Published: February 2015

In offshore pipeline constructions, high productivity is required to minimize pipe laying cost. One of the most significant methods for achieving higher productivity is to reduce the welding defects, which lead to repairs.

Recently, the acceptable level of welding quality, especially the root pass, becomes higher and higher. This means minimizing misalignment between both pipe ends is required to get rid of welding defects triggers.

On the contrary, the tolerances of commercially manufactured pipes have not been revised and shape fluctuation between both pipe ends is not ideal for welding condition. Various line-up clamp systems of pipes have been employed, however their control range is too limited to realize ideal alignment. To solve this problem fundamentally, authors have developed a pipe end forming equipment, to aim at perfect alignment between both pipe ends for girth welding. Applying the equipment, pipe ends are equalized in the shape, i.e. both diameter and roundness, and are fitted easily with each other for welding.

The pipe end forming equipment has two additional features. One is Compactness. The compact design enables its easy installation onto the existing barge with minimum modifications. The other is quick processing. The processing duration does not cause any interruption for the cycle time of pipe laying operation.

This shape equalization between both pipe ends leads to not only elimination of welding defects but also reduction of pipe fitting time prior to welding. We believe that the equipment will highly contribute to improve pipe laying productivity.
New Advances of Formation Testing in the Extreme Tight Gas Reservoirs using new 3D Radial Probe: Case Study in South China Sea
Authors: Cai J. , Guo S. , Gao Y. , Chen J. , Xian C. , Tellapaneni P.K. , Zhang T.
Published: February 2015

CNOOC is operating in YingGehai Basin and QiongSouthEast Basin of South China Sea. Formation testing has been routinely used by this operator in field exploration to confirm hydrocarbon presence, define the hydrocarbon type as well as getting PVT samples. Due to the high cost of DST operation in the offshore environment, formation testing is considered as the main testing method to test the small to medium size sand bodies. And the result is accepted to claim reserve of hydrocarbon.

As the recent offshore exploration has focused more on deeper formation where the sand permeability is between low to ultra-low, the pressure pretest mobility is easily lower than 1md/cp. In some particular formation, the formation mobility is even lower than 0.1md/cp. For this type of permeability of sand, testing becomes very difficult and getting fluid sample to claim reserve becomes a huge challenge. If the formation tester fails to obtain the samples, very often the later DST operation would not achieve a success.

A new probe module of formation tester has been introduced to the industry early 2013 and it has been designed to perform formation testing in low permeability environment. Especially it could apply a much higher drawdown than previous technology to move the tight hydrocarbon.

In this paper, a few cases will be presented to demonstrate how this new probe work in Yinggehai and QiongSouthEast basins fluid sampling operation where we sampled successfully at formation with the mobility is less than 0.1md/cp. With this result, great amount of reserve can be claimed and this new probe has been considered as the unique solution of testing these formation as well as predicting the possible production capability..
Well Performance Workflow Automation: An Integrated Operations (IO) Approach to Unlock the Field Potential for Samarang Asset
Authors: B Ahmad M Zul Izzi , Lajim Sayung Colinus , Muhamed Salim Muzahidin , Hin Wong Lee , Mohd Som Mohamad Kasim , Soriano Jerome , Biniwale Shripad , Nghia Vo Tri , Pedraza Sergio , Soh Kenneth King Han , Hermann Roland , Chong Ee Lau , Trivedi Rajesh
Published: February 2015

Samarang is a 35-year-old offshore oilfield in Malaysia, operated by Petronas. By 2003, with the declining production trends anddwindling reserves, the field abandonment was on the horizon. SamarangRedevelopment Project was kicked-off in 2012 with a vision to implementIntegrated Operations (IO) as an Asset Management Decision Support tool byimplementing a real time production, reservoir and process surveillance system. For the IO implementation, various intelligent asset decisionprocesses referred as workflow were identified and in various reservoir, production, and operations domains suchas Flow Assurance, Well Performance, Artificial Lift, Production and facilityPlanning and EOR Optimization. These workflow groups are linked to provide an integrated asset decision support system whichwill improve decision quality and operational efficiency. workflowm will deliver value with enhanced asset management by focusing on decisions toimprove reservoir drainage, production, and operations. In the initial phase, well performance workflow group, by acquiring data from the SCADA system andprocessing the real-time analysis workflows, enables the asset team to movefrom a reactive to a pro-active asset management system. ‘Well Status andUptime Calculation’ and ‘Well Rate Estimation’ workflow enable engineers to know in real-time the performance andstatus of wells to reduce the production deferment. The ‘Well Test Validation’ workflow will provide online validation, enhanced test quality andimproved confidence in back-allocation and reservoir modeling leading to betterField Management. ‘GasLift Surveillanceand Optimization’ workflow monitorslift performance, performs diagnostics and optimizes gaslift distribution. UsingReal Time data and integrated software, this solution will enable efficientdecisions with a shorter turnaround timeThus workflows equipthe asset team with cutting edge technology and collaborationenvironment for operational decision making. The IO implementation will help to extend the fieldlife and increase recoverable reserves while facilitating an effectivereservoir management strategy.
Recent Advances in the Analysis of Extreme Metocean Events
Authors: Ewans Kevin , Jonathan Philip
Published: February 2015

Accurate and reliable estimates of probabilities of rare, extreme metocean events are critical for optimal design of offshore facilities. They ensure facilities are neither over- nor under-designed, allowing target reliability levels to be achieved without undue conservatism. Engineering design requires metocean parameters to be specified with a return-period of 100 years, but often specification to a return period of 10,000 years is required. Modern hindcast data bases, typically used to derive extremal criteria, can be of limited extent, consisting of data for a few decades; hindcasts with periods of more than 50 years remain unusual. In addition, metocean criteria are often stratified by covariate - seasonality or directionality are common examples. Further, specification of joint occurrence of parameters at long return periods is necessary to avoid excessive conservatism, and such criteria may also need to be specified as functions of one or more covariates. Methods used by practitioners to meet these requirements are often somewhat ad-hoc, based on experience and intuition. In this paper we review recent applications which add statistical rigour and consistency to the estimation of design values. In particular, we present methods for maximising the benefit of limited data sets and deriving consistent extremal criteria with covariate, resulting in criteria that are consistent with respect to multiple covariates, including space, time and directionality.
Watertight Integrity Audits to Mitigate Risks of Progressive Flooding
Authors: Wozniak Chad , Brekke James , Unuvar Merih , Rousseau Joseph
Published: February 2015

Experience in the offshore industry demonstrates that while mobile offshore drilling units (MODUs) are designed to provide watertight integrity (WTI), incidents continue to test the WTI of MODUs. Owner investigations sometimes show flooding has progressed to hull compartments beyond the original breach. With the worldwide MODU fleet increasing to nearly 1,000 units in the next few years, the industry is seeking a greater understanding about the threat of progressive flooding during an incident and the benefits of available control measures. One such control measure to be discussed in this paper is a program of comprehensive, owner-driven audits to verify the crew's maintenance performance. On a vessel built to support a drilling process (e.g., a MODU), maintenance attention naturally focuses on the drilling process. In day-to-day operations, drilling equipment is susceptible to wear and tear, which can occasionally lead to downtime and an immediate need for repair and maintenance. Safety-critical marine equipment might only show flaws on those rare occasions when it must function as intended, without failure, such as in a marine safety drill or emergency. A natural tendency for "complacency" and "errors in risk perception" can affect the timely maintenance of marine equipment differently than drilling equipment. WTI audits address the need to properly assess the maintenance requirements of specific marine equipment on board the vessel. These rig-specific, owner-driven audits would supplement periodic class surveys to verify how well the crew is performing marine maintenance. The benefits that can be realized include avoiding major flooding incidents across the industry MODU fleet; improving industry safety performance, especially for aging rigs, non-self-propelled rigs, and newbuilds; reducing unexpected downtime during out-of-service periods; and increasing the crew's awareness, which can lead to improved competence, quality and safety culture. Ideally, best practices and lessons learned from the WTI audits would be shared with the industry to improve watertight design and owner inspection practices.
A Innovative Liquid Detection Sensors for Wet Gas Subsea Business to Improve Gas-Condensate Flow Rate Measurement and Flow Assurance Issue
Authors: Pinguet Bruno , Smith Michael Thomas , Vagen Nils , Alendal Gro Merete , Xie Cheng-Geng
Published: February 2015

In subsea business, the use of wetgas flowmeter is becoming a standard for deep and ultradeep field development. The business growth is outstanding over the last few years and it is expected to continue at the same path. Furthermore, the tieback of these fields to hosting platform or onshore facility has increased drastically. The critical measurement is not only on high accuracy flow rates but also on water detection with 99.x% of the production being gas. The liquid is initially predominantly condensate phase continuous before becoming more watery with the well ageing. Water is the main concern either in presence of H2S or because hydrate could be formed and will plug the production line. To counterbalance these catastrophic scenarii the chemical use is necessary, but the cost leads to loss of benefit, therefore an optimization is necessary. The need for a reliable water detection became a compulsory practice with constraint to be working initially in oil and water continuous phase. The innovative solution describes in this paper look at how an accurate measurement could be offered at any GVF and WLR based on the use of two different types of measurement having a different response to the water-hydrocarbon contrast and water conductivity sensitivity. This approach led to a development of an innovative add-on on the wet gas meter which provides a high accurate local water fraction measurement that can be comparing with a global measurement. This paper is focusing on the explanation of this innovative analysis after 10 years of work in this direction, and the value brought to oil/gas operator in detection of water and then optimizes the use of expensive chemical. It is also possible to identify clearly, if the water is coming from the formation or not in any WLR mix. It addresses also the use of MPFM beyond the classical metering flow rate performance and focus on the benefits of brought for a subsea flow assurance and reservoir management.