bluuebunny/crossref_metadata_2025 huggingface dataset:
Resistivity Independent Hydrocarbon Saturation Computation across a Lithologically Complex Jurassic Carbonate reservoir, Offshore Abu Dhabi
Authors: Serry A. M. , Espinassous M. , Raina I. , Thum S. , Cig K.
Published: November 2015

The Jurassic carbonate Reservoir-X, offshore Abu Dhabi started to produce hydrocarbons in the early sixties of the last century. The reservoir is generally formed of regressive sedimentary cycles and can be divided into four highly heterogeneous carbonate units with mixed compositions of limestone, dolomite separated by dense anhydrite layers. Down-flank water injection using relatively low-saline sea water had started in the early 1970s. As of the present day, this ongoing process has highly altered the original formation water super-salinity, in a way that the Archie water saturation computation for Reservoir-X is very challenging and not a straight forward practice anymore. The objective of the presented approach is to introduce a resistivity independent saturation across Reservoir-X, using the novel Pulse Neutron Log (PNL) Spectroscopy measurements.

In order to meet the subject challenges; a comprehensive logging suite consisting of gamma ray, resistivity, density, neutron and spectroscopy is used. The particular interpretation methodology is chosen such that it becomes possible to solve for the hydrocarbon saturation using elastic and inelastic capture spectroscopy. A further observed added challenge is the presence of light hydrocarbon and gas in the porous Reservoir-X layers with the unknown mixed-saline formation water in addition to mud filtrate. Here we present a method for hydrocarbon typing across Reservoir-X.

The precise and accurate acquisition of spectral elemental yields allows for a detailed lithological evaluation, hence allowing for an accurate porosity determination, also taking into account wellbore fluid properties that affect the logging sensors due to the presence of formation water and mud filtrate in the formation. This helps to obtain a resistivity independent hydrocarbon saturation that is independent of Archie parameters m, n and water formation salinity. The solution has also been verified by a subsequent, downhole wireline formation tester fluid identification analysis.
Smart Design for High CO2 Removal for LNG Production
Authors: Bowerbank Gary
Published: November 2015

Recent Oil and Gas discoveries provide an increasing outlook of gas fields containing CO2 content between 10 mol % to as high as 70 mol % CO2. The gas needs to be treated for managing CO2 emission and to fulfil treated gas specification for sales gas or for LNG production. The increasing amount of CO2 content in newly discovered gas fields requires smart designs to minimize CAPEX/OPEX while adhering to emissions requirements. Amines and membranes are commercially available technologies for CO2 removal. However, membranes alone can only do bulk CO2 removal and cannot achieve low CO2 specifications (certainly not deep CO2 for LNG specifications). So membranes will often need an amine unit meeting the CO2 specification as a polishing step.

For this paper, a case study based on amine technology will be discussed. The gas contains high CO2 (~20 mol %) which will feed a LNG plant downstream. The treated gas specification is the typical required LNG specification of 50 ppm. Amine technology is a well-proven process for CO2 removal and capable of meeting these stringent specifications, but comes with high CAPEX and OPEX at these increased levels of CO2. In this study a smart design, which involves a pioneering approach, was undertaken which enables reduction of OPEX by 30 %, and capturing a CAPEX gain of 24 % against a conventional amine design.
Improved Fracture Characterization by Utilizing Seismic-Derived Attributes including Anisotropy and Diffraction Imaging in a Giant Offshore Carbonate Field, UAE
Authors: Skeith Gene , Obara Tomohiro , El-Awawdeh Raed , Sultan Akmal , Al Messabi Abdulrahman , Liu Enru , Johns Mary , Zelewski Gregg , Burnett William , Wu Xianyun , Zhang Jie , Molyneux Joe
Published: November 2015

We present a case study of fracture characterization by integrating borehole data with a variety of seismic attributes in a carbonate reservoir from a giant offshore field, United Arab Emirates. The objectives are to determine to what extent seismic data may be confidently used for mapping spatial distributions of subtle faults and fracture corridors in the reservoirs and to better understand the distribution of overburden anomalies (karsts, high impedance channels) for field development planning. Borehole data used in our study include information from core descriptions (fracture density and orientations), image logs, cross-dipole shear-wave anisotropy analysis, and dynamic data (well testing, PLT, tracer, and mud-loss). The seismic attributes include standard and advanced post-stack geometrical attributes; pre-stack seismic azimuthal AVO attributes, and recently developed pre-stack diffraction imaging. We conclude that (1) there are common features that can be identified in different attributes, and the differences may indicate different scales of fractures; (2) There is a qualitative correlation in the area of history match challenges and strong anisotropy, where seismic anisotropy can identify relatively high fracture intensity regions/zones instead of pinpointing individual fractures and complements other attributes as differences do exist between seismically identified fracture zones and well data due to overburden anisotropy, resolution and sampling issues; and (3) diffraction attributes have revealed more detailed geological features in overburden (e.g. karsts) and reservoirs (e.g. lineaments) than in reflection data and a comparison with mud loss data in the shallow zones looks promising with good correlation between mud loss and collapsed features. This work has provided an improved understanding of the applicability and limitations of the using multi-seismic attributes for fracture characterizations in carbonate reservoirs.
Prediction of Carbonate Reservoirs Pore Pressure and Porosity in Onshore Abu Dhabi Using Petroleum Systems Modeling Technology
Authors: Mohamad R. , Fadipe O. A. , Zhang X. , Djuraev O. , MacGregor A. L. , Bouhlel A. M. , Koutsabeloulis N. C. , Noufal A. , Sirat M. , Popa D.
Published: November 2015

Prediction of pore pressure and porosity in an unconventional resource assessment area of Abu Dhabi was performed by using petroleum systems modeling techniques, combining seismic and well data and geological knowledge to model sedimentary basin evolution. The study objective was ultimately to reconstruct basin history and key geological structures as a basis for further geomechanical and fracture prediction studies. Twelve surfaces were interpreted from seismic data and derived from isopach maps. These maps were used to construct the basin model. The model was built from the top of the surface sediment down to the Shuaiba formation. Sediment decompaction was modeled, which enabled the reconstruction of the formation structures through time. Athy's law, formulated with effective stress, was used in the forward modeling simulator for the calculation of pore pressure. Information such as formation ages, erosional events, and hiatus periods were taken into account during simulation. The evolution of porosity, pore pressure, temperature, and thermal maturity through time were simulated and calibrated to measured data. Model porosity is dependent on burial depth, weight of the overburden sediment columns, and lithology properties. Porosity calibration was achieved by adjusting the compaction curve to effective stress. Pore pressure was calibrated by adjusting lithology porosity-permeability relationships. Low-permeability lithologies result in high pore pressure. A regional Paleocene pore pressure reduction was observed, caused by substantial erosion of the Simsima formation. Generally, formation overpressure is observed at greater depth. Additionally, modeled overpressures depend on the evolution of connate water vectors over geological time; these vectors depend on multiple lithology parameters as well as the capillary entry pressure of adjacent model layers. In the Shilaif fm, overpressure zones were identified at the anticlinal structures. Interestingly, higher overpressure was observed in the shallower anticlinal structure. The simulation results provide the estimated porosity and pore pressure in the unconventional play, as well as the reconstruction of the overall basin geometry through time. The resulting models were subsequently used as the basis for further fracture prediction studies; results were ultimately consistent with faults derived from existing seismic interpretation. Model porosity, pore pressure, and predicted fractures will be used for the development of static geological and dynamic reservoir models.
Helical Piles as a Novel Foundation System for Offshore Piled Facilities
Authors: Spagnoli G. , Gavin K.
Published: November 2015

Driven piles are used to support the majority of offshore oil and gas structures with jacket structures supported by axially loaded piles still remaining the most common form of fixed offshore platform. Piles for conventional platforms are normally driven open-ended steel piles. This paper presents general considerations regarding the use of helical (or screw) piles as a novel foundation system for offshore structures. This type of pile has many advantages over driven piles, these include; ease of installation, the ability to remove using a reverse torque technique and cost savings due to much smaller installation vessel requirements. Other uses of helical piles are as support system for anchoring systems used for floating structures (e.g. tension leg platforms, SPARS, semi-submersible production platforms). To investigate their potential a joint research project was performed between BAUER Maschinen GmbH and University College Dublin (UCD). This project to date has involved small-scale laboratory tests, full-scale field tests and finite element modelling. This paper reports the results from finite element (FE) analyses that investigated the effects of the pile geometry, soil stiffness and soil friction angle on the compression and tension capacity of a helical pile in sand. In total, 48 models were created using Plaxis 3D. Axial tension and compression load tests were performed for piles with an embedment depth of 6m. In addition to the FE analyses, a series of laboratory model tests were performed in a large sample of sand at UCD. The primary purpose of these tests was to study the effect of installation method on the capacity of a helical pile. Wished-In-Place (WIP) piles (formed by placing the pile in the testing chamber prior to sample preparation), with helical helix-to-shaft ratios of 1.2 and 2.5 were load tested and their capacity was compared to the piles installed using the torque method. The results of the lab tests suggest that torque installation results in compaction of the sand around the pile. As a result the uplift capacity of the pile of the torque installed pile was much higher than the WIP pile. The wall thickness depending on the maximum applied torque and the permissible torsion stress of the steel is also briefly discussed.
Turbodrill Bottomhole Assembly and Real-Time Data Improve Through-Tubing Coiled-Tubing Drilling Operations in Sour Gas Well
Authors: Ebrahimi A. , Schermer P. J. , Jelinek W. , Pommier D. , Pfeil S. , Flint G.
Published: November 2015

Through-tubing (TT) drilling was used to drill Upper Permian Zechstein carbonates in Germany. The project was partially set up as an experimental performance comparison between a positive displacement motor (PDM) and a turbodrill bottomhole assembly (BHA) equipped with real-time logging tools. This would be a world-first drilling run for this size of turbodrill as well as the first turbodrill run on coiled tubing (CT) using this real-time data feedback.

Through-tubing coiled tubing (TT-CT) drilling incurs significantly lower cost per drilled footage than conventional rotary drilling methods. A dedicated candidate selection process emphasized the geometry and extent of the pay zone, borehole stability, tubing geometry, and well integrity, which are all crucial for the application of TT-CT drilling. As a result of this screening process, well Sh Z1a, a horizontal sour gas production well was selected. Dedicated BHA designs were used for both the PDM and the turbodrill to allow for a direct performance comparison whilst drilling the section.

TT-CT drilling was used to deepen the well. Initially, 410 ft [125 m] were drilled with a 2.283-in. [58.0-mm] impregnated bit and a 2.125-in. [54.0-mm] PDM using 1.750-in. [44.5-mm] CT suitable for sour service. An additional 148 ft [45 m] were drilled with a 2.283-in. [58.0-mm] impregnated diamond bit with polycrystalline diamond compact (PDC) cone cutters. This bit was run with a 2.125-in. [54.0-mm] turbodrill BHA equipped with real-time logging tools using a sour-service-suitable 1.750-in. [44.5-mm] CT with a fiber-optic cable. The section was drilled under total losses and through multiple natural fractures. While drilling with the real-time logging tool, internal and external downhole pressures, torque, and tension and compression forces were recorded to assist in the drilling process. Direct comparison of the PDM and the turbodrill BHA was made for rate of penetration (ROP), weights and pressures. The turbodrill BHA produced more than double the ROP than was possible with the conventional PDM BHA using less weight on bit and showed overall smoother drilling mechanics.

The well is currently on production. The project showed that TT-CT drilling is a viable technology for production enhancement in depleted gas reservoirs and that new turbodrill technology generates significant performance improvements over conventional drilling tools.
Integrated Approach to Evaluate Unconventional and Tight Reservoirs in Abu Dhabi
Authors: Steiner Stefan , Ahsan Syed Asif , Noufal Abdelwahab , Franco Bernardo , Koksalan Tamer , Amjad Kashif , Helja Emina , Alhosani Sabah , Adesanya Akindele
Published: November 2015

ADCO has drilled a number of wells and evaluated hydrocarbon potential of the Middle Cretaceous Wasia Group Unconventional reservoirs onshore Abu Dhabi since 2012. Latest logging and core analysis technologies were applied to assess key parameters such as Total Organic Carbon (TOC), source rock maturity, mineral compositions and fluid saturations, as well as geomechanical parameters such as Young's modulus, Poisson's ratio and minimum horizontal stresses. To date more than 2500ft of core has been extracted, described and analysed. We understand that ADCO has, by far, the largest data base among all the OPCOS with regards to unconventional play and has gained a significant local learning curve ahieved over the last 3 years.

In addition to triple combo data, log data acquired consists of NMR, high resolution lateralog, dielectric logs, and mineral spectroscopy, cross dipole sonic, borehole imaging and sonic scanner, routine and advanced mudlogging. Core analysis consists of crushed rock analysis, pyrolysis and rock mechanics testing. Significantly high mud gas readings, observation of oil staining, odor, and fluorescence under UV light indicate presence of oil over large sections of the acquired cores and side wall cores from various geographically spread wells. Recently, we have conducted 5000 TOC and 1500 Pyrolysis measurements from core and cuttings samples in 110 wells spread all over Abu Dhabi. This data clearly demonstrate that large sections of Wasia Group bear excellent source rock quality in several wells located in large segments of onshore Abu Dhabi. Visual inspection of core and TOC measurements indicate that high frequency jet black centimeter scale organically rich lamellae often exceeding 20% TOC in several wells are not uncommon. The unconventional reservoir rocks are composed of predominantly clean and tight matrix carbonate mudstones and wackestones. Preliminary results of the current exploration campaign within the ADCO concession are very encouraging, showing indications of hydrocarbon presence. Formation testing is planned in the near future to confirm the Unconventional play in Abu Dhabi.

The paper focuses on an integrated multi-disciplinary approach covering petrophysical, geological, geochemical and geomechanical assessment with the ultimate goal to determine optimal parameters for formation testing and production.
Well Integrity Support by Extended Cement Evaluation - Numerical Modeling of Primary Cement Jobs
Authors: Godoy R. , Fontan M. , Capra B. , Kvalsund R. , Poupard O.
Published: November 2015

The cement height requirements for primary cement jobs, or annulus cement, are stated as absolute values in some parts of the world. For example the Norsok Standard, D-010, "Well integrity in drilling and well operations" states that one cement barrier is either 50 meters when verified by displacement calculations, or 30 meters when verified by bonding logs. The requirements do not distinguish between reservoirs with high pressure/ temperature- and reservoirs with typical low pressure/termperature conditions. A numerical method has been developed which considers the current or future well conditions as part of the cement evaluation process. This numerical approach is an additional tool in the decision making process and does not replace existing verification practices. The time to run the analysis has also been an issue to address, since existing tools in the industry (FEM-analysis etc.) can be quite time consuming to run. Additionaly it is also possible to perform analysis up-front the operations and various pre-defined cement length intervals can be compared to the requirements or other upper acceptable cases. Offshore well cases from the Norwegian Continental Shelf have been used as basis in the development and demonstration of the method. The numerical model is based on monophase or multiphase Darcy flow calculations through the cement sheath involving uncertainties like cement permeability, reservoir pressure in the eternal perspective etc. The model allows a parametric analysis in a reasonable computation time and building of a well case library making the process efficient in an industrial comparison perspective. The method is an ‘engineering approach' taking place in the decision making process of well integrity.
Ultimate Use of Pressure Testing While Drilling for Green Field Reservoir Development
Authors: Kilic Akgun , Amer Mohamed Mostafa , Al-Jaberi Salem , Ahmed Husnein Shershad , Clemens Carter , Zidan Maher , Shuaib Mohamed , Vicario Roberto
Published: November 2015

Pressure testing while drilling provides pressure depletion data to better understand the communication between wells and sublayers. In a green field, it may even substantially optimize the well completion and reservoir management strategy.

Pressure testing while drilling (PWD) was performed in a highly deviated well crossing eleven sub-layers of the same reservoir in a new field. An NMR tool was also used for porosity and qualitative permeability measurement and shows a clear seal between the subjected zones. Pressure measurement was conducted at least in two locations of each subzone and draw down mobility for every test was calculated. Pressure data from tested well were compared to initial pressure data from pilot holes and indicated strong depletion from three sub-connected units. The test tool had the flexibility to re-orient if good seal was not achieved during the test.

The successful results from a 3000 ft 6″near horizontal drain demonstrated the ultimate use of pressure testing while drilling could clarify differential depletion among different sublayers. At a different scale, this will enhance reservoir management, optimize well completion and save rig time.

Pressure testing while drilling is an important part of the reservoir monitoring plan in order to get accurate static pressure at the reservoir which can be used to monitor reservoir pressure to understand the dynamic communication and depletion per layer. The objective is to make pressure measurement while drilling a standard procedure for all future wells of the field. The conclusive findings from this study considered to be a good integration practice that will help to improve completion strategy, reservoir management and eventually the reservoir modeling.
Materials Selection for High Pressure Sour Service in the Shah Gas Development Project
Authors: Sahoo Tareq , Keat David , Al Romaithi Saeed D. , Pandey Shyam
Published: November 2015

Al Hosn Gas Company, a 60/40 JV between ADNOC and Oxy has been undertaking a project for the development of an extremely sour gas reservoir in order to increase production of injection and sales gas. The Al Hosn Gas plant is designed to process 1,000 MMscfd of non-associated sour gas.

The gas reservoir is very sour with H2S levels of 23% together with 10% CO2 and other corroding components such as 20,000 ppm chlorides and 5 bbl/MMSCF water.

The bottom hole conditions make the overall environment very aggressive for any conventional material e.g. carbon and alloy steels.

Processing of such sour feed posed a significant design challenge. Materials selection for production tubular, gas gathering lines and process equipment was the main strategy to ensure plant integrity.

The well fluid can reach high temperatures. To protect against external corrosion the carbon steel backing material for flow and trunk lines was coated with high temperature epoxy.

Four exotic materials were selected and subjected to 30 days exposure test in autoclave at simulating gas gathering lines conditions. Two materials were further subjected to closer scrutiny with a series of potentiodynamic polarization tests and metallurgical analysis.

This paper deals with the materials identification evaluation, test procedures, test details and final selection together with applicable fabrication procedures.
Real-Time Integrated Optimized Drilling Technology for Deep Carbonate Formation
Authors: Wei Liu
Published: November 2015

For deep carbonate formation, there are many drilling problems in applications, such as hydrogen sulfide distribution, narrow pressure window, strata complex, objective layer pressure sensitive, which lead to drill ahead and improve the rate of penetration (ROP) very difficultly. And carbonate reservoir comprises many fractures and caves which must be connected as more as possible to form a longer petroleum channel for increasing single well production.

In order to solve above problems, an integrated optimized drilling technology is raised to realize these challenges which includes three important points of innovation. Firstly, it is the horizontal well optimized design along top boundary of fracture-vuggy formation to realize the longest horizontal section because of petroleum inside fracture or vuggy. Secondly, it is to increase ROP by minimal mechanical specific energy and micro underbalanced pressure drilling method to optimize drilling parameters. Thirdly, it is to develop managed pressure drilling (MPD) in complex conditions to monitor annular pressure in real-time and keep downhole pressure constant or whole circulation flowrate stable.

The new design can help us get more opportunities to increase the production of single well effectively. The real-time integrated control method can realize ROP significantly, such as get about 39% improvement than before in Tarim oilfield. If no harmful gas or a little harmful gas come out from formation, micro underbalanced pressure control drilling technology may be most applicable method to develop deep carbonate formation because it can control well kick at a small rate to find pay zone, keep well wall stable and improve ROP. In sum, after many field applications in deep carbonate formation, it is proven that the integrated optimized drilling technology can break through the traditional drilling technology to extend horizontal section as long as possible (present record of longest horizontal length is 1561m), find more pay zones and overcome the drilling problems in deep carbonate formation to realize safety and fast drilling and gain maximal economic benefits.

In contrast to conventional real-time control method, the new technology considers the design about how to extend the horizontal section length along the top of frature-vuggy structures which is safety and effective in reality. At the same time, we adopt new real-time parameters optimization and managed pressure drilling to solve different problems and also improve drilling effect. Therefore, especially for deep carbonate formation development, the new real-time optimized integrated drilling technology should be gotten more and more applications for develop effectively.
Multi-scale Geomechanics: How Much Model Complexity is Enough?
Authors: Hoedeman Gerco
Published: November 2015

Nowadays oil and gas exploration and production is often performed in geomechanically challenging enviroments where the risks can be high and problems are costly. Choosing the right scale and complexity of a model is critical for performing an effective and efficient geomechanical analysis that addresses the problem without unnecessarily expending resources like time, computation power or software license costs.

In this paper different geomechanical modeling techniques are compared for their accuracy and efficiency using a relatively simple (continental slope) and a more complex geological setting (submarine canyon). This has been done by comparing the resulting state of stress of 1D well-centric geomechanical models with those of reservoir-scale 3D geocellular and 4D finite-element models.

The more complex submarine canyon model shows that in relatively complex areas the 1D and 3D geomechanical models no longer give accurate stress results and a 4D model is needed to accurately simulate the state of stress. On the other hand, the continental shelf model shows that in a simple geological setting creating a 1D wellbore-scale geomechanical model is an efficient and effective way of calculating stress. The 1D model gives an accurate state of stress comparable with the more complex 3D and 4D reservoir-scale geomechanical models. Not having to create, simulate and analyze a reservoir-scale model can save time for better analysis of the results, dealing with uncertainties of the model and/or doing a sensitivity analysis.

The paper concludes that the initial step in a geomechanical study is assessing the geomechanical application of the model, taking the complexity of the geological setting into account and based on that assessment chosing the modeling complexity that is necessary to get accurate results, without unnecessarily spending resources.
Unlocking the Potential of Marginal Reservoirs in Kuwait Through the Application of Optimized Hydraulic Fracturing Technologies
Authors: Al-Othman M. , Al-Houti N. , Anthony E. , Aloun S. , Mokhtar A. , Sheikh B.
Published: November 2015

In Kuwait, drilling and deployment plans focus mainly on drilling vertical wells through a wide range of reservoirs consisting of high- and low-permeability sandstones and carbonates, with varying crude types from medium-heavy to condensate. Since 1935, Kuwait has produced mainly from the types of reservoirs that keep its daily production as high as possible to accommodate the country’s economic needs. With the aging of these mature reservoirs, reservoir pressure reduction and water production become a major challenge, in addition to the limited access to drilling resources. Accordingly, exploring different reservoirs and unlocking the potential of the existing low- to mid-permeability reservoirs through advanced fracturing technologies are considered the alternative plan to compensate for production decreases and to improve oil production. However, implementing such technologies requires a customized design and candidate selection process.

The plan involved a multidisciplinary well candidate screening and selection criteria for different reservoirs and fields. The criteria include different parameters such as bubblepoint pressure, minimum formation thickness, and rock mineralogy, in addition to the study of the previously applied production enhancement technologies. About 50 wells have been selected from different reservoirs and fields across Kuwait for the initial pilot plan to evaluate the potential of a wide range of reservoirs. Then, a customized fracturing technology design followed that included operational planning, execution, and evaluation.

Approximately 20 fracturing treatments were executed successfully, and the post-job evaluation showed two- to four fold gains in production. This changed the development strategy and allowed for further development plans for these reservoirs. These newer plans included the application of technologies such as channel fracturing for proppant fracturing and fiber-laden self-diverting acid system for acid treatments.

The well candidate selection criteria and customized design of channel fracturing technology for the sandstone reservoirs and fiber-laden self-diverting acid system technology for fractured carbonate reservoirs resulted in a total additional gain of approximately 15,000 B/D. The detailed engineering design from candidate selection to treatment and the application of optimized hydraulic fracturing technologies enabled production enhancement and additional recoverable reserves from the most challenging low-permeability and low-API gravity candidates for the first time in Kuwait where conventional stimulation techniques were not providing the expected results.
Systematic Approach to Early Identification of Control Systems Interfaces for Large Brownfield Oil & Gas Projects
Authors: Mukunda V. , Panditaradhyula S. S. , Tighilt M. , Thallapalli B. , Das A. K. , Al-Akel M. A.
Published: November 2015

We have 2 major fields Zakum and Umm Shaif which are one of the biggest offshore reservoirs in the world. Our brown field challenges in offshore are limited to those fields. In addition to which there are numerous new green field projects which are also in the pipeline.

One of the main challenges in any brownfield project (big or small) is to avoid the unexpected changes or "surprises" that are often uncovered during detailed design or worse-still during offshore construction. These surprises tend to cause projects to recycle, exceed budget and/or extend schedule. More importantly, they can affect the ability to obtain an inherently safe design where the risk is ALARP.

This risk can further increase as the facility ages and modifications are made. As new projects come to the existing facility, the proposal for new equipment and hazards can make it extremely challenging to find the best solution for both the existing facility and the project.

There are myriad challenges faced in any brownfield project- Shortage of space, shortage or lack of electric power, pressure on production which will make brown field schedules unviable and lastly the hazardous nature of the industry which is a factor to be considered for all scenarios.
Energy Management System
Authors: Al Ameiry Ahmed , Al Breiki Hana , Abdulla Haitham Salmeen , Ali Nafisa
Published: November 2015

Energy is an essential business input. A strategic approach to energy use can improve profitability and reduce environmental impacts, despite the task being herculean, involving careful planning, unified approach between departments and above all, addressing the issue of resistance to change. ADGAS implemented an Energy Management System (EnMS) which not only covers plant operations but considers each and every aspect of the organization. Equipped with procedures, tools and manuals, the system went beyond to plant the concept of energy efficiency and conservation to the minds of employees working in different departments. The achieved savings of 12,670 TJ for the first 6 months in of 2015 helped in a reduction of 57,000 tons of CO2, GHG emissions. More than 90 Energy Performance Indicators had to be created along with corresponding baselines and then Significant Energy Users were selected to focus on improving the energy performance durng the course of a calendar year. On the whole, it was a tough task but the efforts of ADGAS team made it possible. The management also showed its commitment by issuing ADGAS Energy policy along with following up progress and outcomes on semiannual basis. After developing a robust energy management system, the way forward is to develop an energy transformation strategy and ensure continual improvement of the system through audits either internal or external.
Experimental Investigation of Oil Recovery from Carbonate Reservoir Rocks Under Oil-Wet Condition: Waterflood, Gas Injection, SWAG and WAG Injections
Authors: Fatemi Mobeen , Shahrokhi Omid , Sohrabi Mehran , Vieira Raphael , Ahmed Kamran
Published: November 2015

Gas injection schemes (including WAG and SWAG injections) are among the most widely used Enhanced Oil Recovery (EOR) processes for carbonate reservoirs due to their usually low rock permeability. Because of the complex nature of carbonate reservoirs (structural heterogeneities and mixed- to oil-wet conditions), most of the existing reservoir simulators are not able to adequately model EOR processes in these reservoirs. Performing reliable laboratory experiments in reservoir cores under reservoir conditions is necessary in order to evaluate the performance of these oil recovery techniques and obtain the required data to assess the prediction of the currently available models in commercial simulators.

In this paper, we present the results of a series of coreflood experiments performed in carbonate rocks. Both reservoir core plugs as well as a dolomite outcrop core were used in the experiments. The cores were aged in reservoir crude oil to restore wettability. Gas and water injection experiments were performed under reservoir conditions and with different injection strategies. Separate multi cycle WAG injection experiments were performed starting with gas (WAG-DI) or water injection (WAG-ID) in order to compare the impact of the order of fluid injection. SWAG injection experiment was also performed with an injection gas to water ratio of unity. The injectivity and production data of different injection strategies were compared. Generally speaking, dolomite cores showed less oil-wet characteristics compared to reservoir carbonate cores which showed strongly oil-wet behaviours. WAG injection starting with waterflood and SWAG injection performed better than waterflood or gas injection alone. Ultimate oil recovery by gas injection was considerably less than that obtained by waterflood. As a result of poor efficiency of the gas injection, the WAG injection starting with gas injection (WAG-DI) showed lower recovery performance compared to the waterflood up until the end of 3rd WAG injection cycle. Nevertheless, WAG-DI ultimately outperformed waterflood. Although SWAG injection outperformed the WAG-ID for the first two cycles of injection but the ultimate residual oil saturation was lower for the WAG-ID injection. In addition to lower ultimate oil recovery, SWAG injection test showed more injectivity issues compared to the WAG-ID injection sequence. The observed trends of residual gas and oil saturations in carbonate reservoir cores were different compared with those of water-wet and mixed-wet sandstone rocks reported in our previous studies in which the residual oil to water was reducing linearly with an increase in trapped gas. The results provide useful insights into mechanisms of oil recovery by gas and water injection in carbonate reservoirs and highlight some important differences with sandstone reservoirs.
Experience on Custody Transfer Using MPFM
Authors: Yusuf S. A. , Menchaca T. F. , Altaf B. , Khan M. N.
Published: November 2015

During the initial development phase of a new field operated by Abu Dhabi Marine Operating Company (ADMA-OPCO), due to the unavailability of processing facility, produced fluid is designed to flow into a pipeline operated by Zakum Development Company (ZADCO). The produced fluid is metered using two Custody Transfer Multi Phase Flow Meters (MPFM) with a normal operating philosophy of one-operating-one-standby and can be operated in series for verification purposes. This paper discusses the operational challenges for the custody transfer of ADMA fluid to ZADCO processing plant.

The challenges discussed in this paper are due to low production during commissioning and commingled production from multiple reservoirs.

During commissioning of the production platforms, the production was lower than the operating envelope of the meter. This would result in significant error in the meter readings. Since there was physical separation between the production facility and the metering is about fifteen kms away, the time lag between the meters and the production platform did cause further uncertainty in the measurement. To overcome this challenge a strategy was developed to meter the produced fluid with most accurate meters as available at each stage with consensus from both parties.

The commingled production from three reservoirs with significant difference in parameters posed challenge for the use of appropriate PVT properties in the custody transfer MPFMs for the conversion from line condition to standard condition. This was overcome by performing sensitivity analysis on the mixtures, developing PVT tables for commingled production ratios based on reservoirs and implementing a process on the selection of the appropriate table based on the changes in production contribution from the different reservoirs.

Other minor operational issues related to the MPFM metering are also discussed in the paper.
Enhanced SIMOPS Expect Additional 3 Million Barrels of Oil Production and Increased Injection Rates
Authors: Salman Mohamed Wajeeh , Warraich Awais , Moussa K. Abdel-Ghani
Published: November 2015

Simultaneous Operation (SIMOPS) i.e. concurrent execution of two or more activities at the same time and place, which due to their interaction result in increased operational complexity and level of risk.

While challenging existing practices, team has benchmarked Company practices with shareholders, other OPCOs and Service Providers. All the activities having major impact on Production/Injection shut down were captured. Industry standard risk management approach followed to assess all the risks associated with each individual activity. After reviewing all the hazards and safeguards in place, activities were declared as Permitted / Restricted /Not Permitted.

In total 17 activities were reviewed, 11 activities assigned as "Permitted", 4 activities as "Restricted" and 2 activities remained "Not Permitted" under SIMOPS.

By enhancing SIMOPS efficiency by 30%, expected 3 Million Barrels of additional Oil production per year and increased injection rates. Saving above 150 Million USD per year (using current oil price of 50$/bbl). Benefits will further magnify after full scale implementation of multiple SIMOPS per field and increased rig activities in future.

Enhanced SIMOPS efficiency helped the Company to increase effective production capacity and achieve its sustained production assurance milestones without any compromise on safety and with no additional cost.
CNPC Occupational Health Management Model and Results
Authors: Xu Wenbo , Men Xiaotang , Ye Hong , Du Weidong , Huang Zhiling
Published: November 2015

Being as one of China's largest oil and gas producer and suppliers, China National Petroleum Corporation (CNPC), with more than 1,500,000 employees, has about 90 large and medium subsidiary enterprises, and occupational hazard inevitably occur during the construction and production operation, which has the characteristics of wide geographic distributions, enormous employees contacting hazard factors and various hazard factors resulting in occupational diseases. According to the characteristics of occupational disease hazard factors in petroleum and petrochemical industry, and characteristics of occupational health hazards for oversea operations and field operations, CNPC has set up its own occupational health (OH) management models to control occupational disease hazards from the source. In recent years, 92–97% of the employees contacting hazard factors have passed occupational health examinations and there were no hazard accidents of occupational diseases. Therefore, the job concerning OH has obtained satisfactory results.
WellCON: An Early Kick Detection System
Authors: Velmurugan Naveen , Bansal Gopal , Sharma Tushar
Published: November 2015

The main objective of the work is to provide an automated system of early kick detection and control system which monitors and reports the physical conditions of the inside of wellbore annulus instantaneously through time measurements of primary waves propagation through the annulus. This system is graphically modelled as virtual instruments using the software, LabVIEW and is named ‘WellCON’ by authors. Authors propose a model in which time taken for this wave propagation in the annulus reveals the physical condition of the wellbore and denotes the fluids present in the annulus. In case of an unexpected event of kick, the model instantaneously provides the type of fluid in the kick and notifies the driller. To understand the capacity of the well to take a kick, kick tolerance are calculated at every instance of drilling. Based on the severity of the kick influx, considering the tolerance level, commands are sent to BOP to shut-in, leading to complete automation of the kick handling system.
GPS Aided Oil Spill Tracking and Mapping System: Application to Offshore Petroleum Industry
Authors: Velmurugan Naveen , Belay Masho Hilawie , Linse Christoph , Dai Yukun , Navas Sergio Sánchez , Ramesh Kumar K. C.
Published: November 2015

There are varied types and severity of marine oil spills. Authors focus on the oil spills that are results of a blowout especially in the offshore petroleum industry. Blowouts are considered as nightmare situation for oilfield workers and oil blowouts from offshore rigs are horrible disasters causing loss of human lives, oil spills causing damage to marine life and environment besides huge economics impacts. Precise information about time course or the extent of oil spill is crucial for fast and effective response. This paper describes the result of a work carried out by the authors to design and develop an autonomous offshore oil spill system that is robust, financially affordable and suitable for day and night operations. Authors propose an arrangement of anchored and floating buoys fitted with GPS (Global Posistioning System) as described in this paper for real time tracking and mapping of an oil spill. Experiments and computer simulations have been conducted to test the efficiency and working methodology of the proposed system.
Comparison of Condensate Recovery by Hydrocarbon and Nonhydrocarbon Injection
Authors: Gohary Mohamed El , Bairaq Ahmed Mohamed , Bradley David C. , Saeed Yaway
Published: November 2015

The challenge in the development of gas condensate reservoirs is to recover the most valuable hydrocarbon component, "condensate". Pressure drops below the dewpoint anywhere in the reservoir cause condensate dropout. When the pressure drops near the producing wells, condensate banking can occur, which impedes production. Gas recycling is one of the efficient ways of developing such reservoirs because it maintains reservoir pressure and hence increases the condensate recovery.

Demand for gas has resulted in a strategy of nonhydrocarbon (NHC) injection in selected areas of the field. An NHC method under study has the potential to raise the dewpoint of the reservoir fluid making it more susceptible to condensate dropout. The objective of this study was to quantify the effect of NHC injection on recovery of condensate and hydrocarbon gas and the effect on productivity of wells. In this study, sector models are extracted from a full field model. The molar recovery of hydrocarbon component and condensate recovery were analyzed under the effect of reservoir properties and distance between wells and injection stream. NHC breakthrough time and tracer modeling were also studied.

The NHC under study was found to be inefficient compared to the hydrocarbon injection in all cases; however, the properties of the rock and distance between wells impact the efficiency. The difference in recovery factor at two pore-volume injection with NHC injection was nearly 5% less than that with hydrocarbon injection at pressure 4,700 psi, and this difference increased to 10% at 3,000 psi. NHC is poor in revaporizing the condensate dropped in the reservoir whereas hydrocarbon gas can efficiently revaporize condensate either by first-contact miscibility or by a multicontact miscible process.
New Innovation Improves Performance and Reliability of Downhole Plugs
Authors: McGowan Robin
Published: November 2015

Sealing technologies provide a vital role in a wide range of applications no more so than in the design and development of Retrievable Bridge Plugs (RBP) where performance is a vital safety and operational consideration. Moreover, for workover operations using RBPs it is also essential that deployment and recovery are equally as reliable as the pressure and temperature performance of the plug.

Traditional retrievable bridge plugs based on solid elastomeric seals have been the mainstay of well intervention since the 1940’s. However, the long-term shift towards gas production, higher pressures, higher temperatures and increased regulatory standards means these systems can no longer provide the performance the industry demands. New innovative technologies are needed to bridge this gap and this paper provides evidence of once such technology with the potential to service the next era of exploration and production. The paper explores some of the operational and practical limitations of traditional solid elastomer sealing technology for RBPs and introduces a new type of hybrid metal-polymer seal offering significantly improved sealing performance, larger running clearances and enhanced reliability. The new seal technology is described alongside experimental data on the seal’s performance and operational configuration.
Assisting Extension of Life for Aging Assets with Deluge System Technology
Authors: MacKenzie Hugh , Jones Callum
Published: November 2015

Extending the life of aging assets is an important topic in an industry where many platforms are operating beyond their initial planned life. Preserving an asset over 40 years is particularly problematic when operating in environments such as the Middle East and the North Sea, where platforms are exposed to some of the harshest conditions in the world. This paper will outline a ground breaking technology, developed to enable operators to test deluge systems without the need for water, mitigating the issues associated with wet testing and helping extend the life of an asset.

The current industry practice to verify compliance of a deluge system is to perform a wet test. This involves flowing seawater through the system to the nozzles at which point it is directed over a designated area. This technology circumvents the main source of the issues which cause corrosion. This technology will be detailed, from proof of concept to deployment in field and the benefits which this brings in comparison to conventional wet testing and other dry-testing technology.