bluuebunny/crossref_metadata_2025 huggingface dataset:
Developments in Marine Seismic Acquisition: Wide-Tow and Beyond
Authors: Hager Ed
Published: November 2016

The future demands of exploration demand new techniques which increase the efficiency or quality, or even both of marine seismic data. This can be achieved by using the latest geophysical acquisition techniques and geometries in conjunction with developments in processing.

By using recently developed deflectors large wide-tow streamer spreads have become possible which allow for regional 3D surveys to replace 2D surveys, at a relatively low cost increase, but reducing the asset development time by basing initial target evaluation on 3D, albeit low quality, rather than 2D. To gain conventional quality 3D survey the lines can be interleaved to halve the cross-line bin size at a later date where needed based on the initial interpretation. We can also look to incorporating wide spreads with more than two sources –this maintains the spatial sampling and hence quality-but requires shorter shotpoint intervals so that inline fold is maintained. This implies that shots will overlap and that in processing shot interference removal is needed, but it is worth noting that the shot interference would typically start 5 seconds below the water-bottom, which is generally deeper than most targets and so a low-risk for interpretation, especially QI. We can even extend to five sources allowing for fine cross-line sampling for high-resolution surveys and by varying the streamer separations we can achieve an efficient acquisition. To achieve 5 sources with a reasonable volume the sub-arrays are used in more than one source definition and by spacing them equally the source separation can be maintained at 12.5m.

The removal of interfering shot energy is demonstrated on the Capreolus survey, North-West Shelf Australia where the survey covers data from very shallow water, ~100ms to very deep at several seconds showing the interference can be removed in a robust way in a variety of geological settings. Further the 5 source acquisition performed on the Baxter area, also NWS Australia, validates that fine cross-line sampling can be achieved in an efficient manner and is compared to a reference survey with a conventional geometry acquired at the same time. The conclusion from these two surveys is that the ability to remove interfering shot energy combined with multiple sources gives rise to a new range of options within marine seismic

The use of novel multi-source and/or wide-tow marine geometries finally opens up the possibilities in acquisition which then allows the operator to match better survey requirements to the development time-frames and costs.
Case Study: Forecast Performance of Potential Zone Using Artificial Intelligence AI in Deltaic Mature Field
Authors: Respati Pradhipta Seno , Ardan Cesti , Alfaqih Muchammad R.
Published: November 2016

Having characteristic deltaic sandstone with 72 multilayer reservoirs with 252 perforation history became more challenging when determining potential zone. It is challenging because most of all have already produced. Regarding low oil price, high success rate on evaluating potential zones are needed. Developing an artificial intelligent (AI) to evaluate performance of potential zone based on perforation history and log evaluation could increase its success rate.

Since log evaluation is used to determine potential zone, basic log evaluation parameter is used as input. There are also several zone characterizations to made AI more accurate such as; water zone, tight zone, and coal zone. Production history was used as an output and converted as 0–1. The output of this AI expected to predict cumulative production in one year in 0–1 index by iterated using Bournazel – Jeanson water breakthrough model to predict performance.

Artificial Intelligent has been implemented while determining workover program. There are eight workover programs that have been executed. All of them give an expected result based on artificial intelligent prediction. Three programs has been executed and produced more than a year. The production performance created by artificial intelligence are quite match within actual performance.
A Systematic Drilling Hydraulics Optimization Method for Improving Rate of Penetration and its Application in Ultra-Deep Wells
Authors: Meng X. , Zhou H. , Fan H. , Peng Q. , Deng S.
Published: November 2016

With the oil and gas exploration and development in deep formation and the number of deep wells grow continually, the ROP decreases greatly and the cost of drilling operation increases rapidly. A comprehensive procedure of optimization hydraulic design for improving ROP was formulated. It can conduct the integrated hydraulics design to improve ROP not only during making the drilling design, but also can generate recommendations of hydraulic optimization for improving ROP in the process of drilling based on the real-time drilling situation.

First, this paper presents a mathematical analysis of the hydraulics (Bit pressure drop, bit specific hydraulic horsepower, et al.) influence on the ROP based on the drilling engineering data of several wells of Tarim basin in west China,. In order to eliminate the influence caused by the difference of the other drilling data, all of them were normalized in this process. Second, according to the problem that no single rheology model can describe exactly the rheological properties of all types drilling fluids, a systemic hydraulic optimization approach was established, which is applicable for all common rheological models. For improving the design precision, the flow channel both in pipe and annuli was divided into several sections and the flow regime change of each section was considered. Moreover, for maximizing the ROP, the size of drill pipe size was considered during the process of hydraulics optimization.

The technology has been applied in several wells in Tarim basin of China and the test formations are about 3535m-6935m depth. Based on the novel and systematic method, the optimal drill assembly, flow rate, pump pressure, nozzle combination and others drilling parameters were all obtained. The results show that the ROP of these wells were improved about 10.5%~80%.

Through the application of the proposed method, the results show that the ROP in deep and ultra-deep well has been improved obviously, and which have decreased the cost of drilling operation greatly. Therefore, this method can afford an effective approach to improve ROP in deep well.
Horizontal Wells with Multistage Transverse and Longitudinal Fractures - What is the Optimal Production Scenario? Examples from Carbonate Reservoirs
Authors: Rahim Zillur , Al-Kanaan Adnan A. , Soliman M. Y. , Pacheco Eduardo
Published: November 2016

Strong demand for energy during the last decade influenced the increase in horizontal wells with multiple fracture stimulations. The strategy helped in increasing oil and gas production to meet the demand of internal and external markets.

Wells with transverse fractures have been the first option in low-permeability shale, sandstone, and carbonate formations. This is to increase the number of independently growing fractures thereby increasing the contact area. The fractures propagate transverse to the wells as they are drilled and completed in the direction of maximum in-situ stress (σmax). Many authors, however, have reported that in sandstone reservoirs, the efficiency of transverse fractures is affected by proppant pack permeability reduction due to non-Darcy flow. The study focuses on the best completion option for gas wells in terms of production performance and logistics that will ensure optimal field development.
Deep-Spectrum Gaschromatography and Carbon Isotopes Analysis While Drilling Enhance Value of Real-Time Formation Evaluation, Reducing Interpretation Uncertainty
Authors: Ferroni Gionata
Published: November 2016

Mud gas data represent the "first breath" of a well being drilled. However, despite significant progress in technology, techniques and theoretical understanding of mud gas detection and analysis, such data are still largely under-utilized by formation and fluid evaluation specialists.

This paper addresses such issue; it presents how new mud gas data realistically expand the limits of surface logging and redefine interpretation uncertainties.

The modern analysis process of hydrocarbons detection while drilling rests on three legs: First, advances in mud gas detection enable to analyze a broader spectrum of hydrocarbons directly on site, detecting more than 30 hydrocarbon species from methane to n-octane. This is coupled with the analysis of the carbon isotopic fingerprint of light components at the wellsite.

The second leg is constituted by a robust procedure covering all aspects of data acquisition, quality control and interpretation, applied systematically to the analysis process.

Finally, the third leg is the integrated utilization of all formation data available, from surface and downhole sources.

The principles described above have been applied in several projects worldwide. One of the main results is a significant reduction in the uncertainty in fluid-type indication. In fact, the utilization of chromatographic and isotopic data, simultaneously collected by entirely independent instruments, leaves limited doubt in fluid typing.

Furthermore, early isotopic data have permitted understanding some of the reservoir characteristics without waiting for laboratory sample tests.

Another important result is that the utilization of early formation evaluation data has enabled to optimize downhole data acquisition programs, with significant cost savings.

In all the successful cases, data interpretation has been carried out taking into account the geological context and utilizing models validated with laboratory data. The application of specific analysis procedures has also resulted in identifying reducible and non-reducible limits of mud gas detection and analysis.

The overall result of this approach is a significant reduction in data uncertainty in mud gas data. In the same time, it provides a realistic review of how far the analysis of light hydrocarbons can be extended, given the recent technology advances. Ultimately, a critical approach to surface logging-based formation evaluation techniques leads to a better understanding of the significance of such under-utilized although cost-effective data, and indicates the way forward for further development in this discipline, based, it should not be forgotten, on the direct and early analysis of the formation fluids.
Use of Nickel Nanoparticles for Promoting Aquathermolysis Reaction During Cyclic Steam Stimulation
Authors: Yi Siyuan , Babadagli Tayfun , Li Huazhou Andy
Published: November 2016

Late cycles of cyclic steam stimulation (CSS) are characterized with a decreasing heavy-oil recovery and an increasing water cut. Nickel nanoparticles can be used to promote aquathermolysis reactions between water and heavy oil in steam injection processes, thereby increasing the recovery factor. In this paper, detailed investigations were performed to determine the optimum operational parameters and answers to the following questions: (1) What is the optimum concentration of nickel nanoparticles for promoting aquathermolysis under high steam temperature?; (2) Can we improve oil recovery at lower steam temperatures with the presence of nickel nanoparticles?; (3) What effect does the penetration depth of nickel nanoparticles have on the final oil recovery?

CSS experiments were conducted between temperatures 150°C and 220°C. Steam generated under these temperatures was injected into sand packs saturated with Mexican heavy oil. Powder-form nickel nanoparticle was introduced into this process to boost the oil production. In an attempt to obtain the optimum concentration, different concentrations were tested. Next, oil sands without any nanoparticle additives were first added into the cylinder. Then, only one third of the sand pack was mixed with nickel nanoparticle near the injection port. Experiments were executed to study the effects of temperature, nickel concentrations, and nanoparticle penetration depth on the ultimate oil recovery and produced oil-water ratios after each cycle. Produced oil quality and emulsion formation were evaluated with gas-chromatography (GC) analysis, viscosity measurements, saturates-asphaltenes-resins-aromatics (SARA) test, and microscopic analysis of the effluents.

Experimental results show that the best concentration of nickel nanoparticles, which gives the highest ultimate oil recovery factor, is 0.20 wt% of initial oil in place (IOIP) under 220°C, while the nickel concentration of 0.05 wt% provides the highest recovery factors at the early stages. A lower temperature of 150°C provides a much lower recovery factor than 220°C, which is mainly due to a lower level of aquathermolysis reactions at 150°C. By analyzing the compositions of produced oil and gas samples with GC and SARA, we confirm that (1) the major reaction mechanism during the aquathermolysis reaction is the breakage of C-S bond, (2) the nickel nanoparticles can act as catalyst for the aquathermolysis reaction, and (3) the catalytic effect becomes less remarkable from cycle to cycle. One run of experiment to test the effect of particle penetration depth revealed that nickel nanoparticle distributed near the injection port greatly contributed to the ultimate recovery factor.
Simplified Local Density Theory for Modeling Adsorbed Gas and Estimation of Gas-In-Place of Unconventional Gas Condensate Reservoirs
Authors: Ma Yixin , Li Baoyan , Mezzatesta Alberto , Jamili Ahmad
Published: November 2016

In shale formations, a large amount of hydrocarbon fluid is stored inside the organic matters where the pore sizes are in the order of nanometer scales. Inside these nanopores, the interactions between the fluid molecules and porous walls play such an important role that can change the fluid properties of the stored hydrocarbons, causing adsorption. For unconventional gas condensate reservoirs, the adsorption of gas could be multi-layers adsorption, because of the small pore size and heavy hydrocarbon components in the kerogen source rocks. A Langmuir isotherm is not valid for modeling the adsorbed gas content and estimation of gas in place (GIP) for shale gas condensate reservoirs, because it is based on the assumption that the adsorption is a single molecule layer adsorption.

To accurately determine the film thickness and density of adsorbed gas, we introduced the Simplified Local-Density (SLD) theory coupled and combined it with modified Peng-Robinson Equation of State (EOS) to model the thermodynamic behavior of the adsorbed gas and free gas of multi-component hydrocarbons, considering the pore confinement of the source rocks. The proposed method is applied to compute the Gas-In-Place (GIP) at initial condition of shale gas condensate systems. A GIP model considering the effects of adsorption was developed based on results from the SLD model.

We first validated the model by comparing the results with available literature data. We also performed the sensitivity analysis and found that fluid density distributions in nanopores were temperature, pressure, pore size and fluid composition dependent. In general, the adsorbed amount increased by increasing pressure and decreased by increasing temperature. Heavier components tended to accumulate near the wall (adsorbed phase) while lighter component would like to stay in the center region of the pore (bulk phase). Then we performed a case study of real reservoir fluids in condensate window of Eagle Ford shale and calculate the adsorbed gas content and the total GIP using the introduced model. The preliminary computation results showed that the adsorbed gas could take more than 30% of gas in place in Eagle Ford shale.

By using the introduced method, the adsorbed gas content and the total GIP in unconventional reservoirs can be calculated with good accuracy under short computational time. This makes the model useful when implemented into reservoir simulators.
A Novel Approach to Develop and Characterise Reservoir Properties in Multi-Layer Completions
Authors: Aguilar C. L. , Berzou M. , Al-Mannai A. , Nada H. , Al-Kharaz H. A. , Al-Buainain M. , Al-Mohannadi M. I. , Morshidi L.
Published: November 2016

Monitoring individual layer performance (in commingled completions) and integrating the results into an overall understanding of field performance has always been a challenge. Overcoming this challenge allows for a better, layer-by-layer, understanding of the reservoir, and therefore will have a significant impact on well and reservoir management. This paper presents a success case for the integration of a novel approach, and specific applications are highlighted.

The Khuff Formation of the North Field is a multi-layered carbonate reservoir formed from four main reservoirs; K1, K2, K3 and K4. As most of the RasGas wells are completed commingled through the main Khuff reservoirs, a hybrid approach for integrating multi-layer pressure transient analysis (PTA) with production logging tools (PLT) analysis of flow and pressure profiles was developed. The process also accounts for the physics of carbonate matrix acidisation. The outcome of this technique has helped RasGas better assess the stimulation effectiveness in commingled wells, and establish baseline performance for individual layers. This work was used to build improved inputs for reservoir simulation models, thus providing more accurate predictions of reservoir performance. Additional benefits of this technique have been: 1) identification of wells with impaired productivity (candidates wells for re-stimulation), 2) a better understanding of the stim jobs (areas for improvement for future jobs), and 3) an improved understanding of log kh vs test kh variation (to understand specific questions on well performance).

This paper discusses the outcomes, applications, and the added value of this integrated methodology. The paper will also demonstrate examples where the technology was applied and the value that was added to the ongoing surveillance and future development activities.
Comparison Study of Two Different Methods on the Localised Enkf on SAGD Processes
Authors: Huang Yingchao , Zhou Xiang , Zeng Fanhua
Published: November 2016

The localization on the automatic history matching of SAGD processes has not been studied. Also the distance-based localization is not applicable to SAGD processes. That is because in SAGD processes oil is produced mainly from the transition zone instead of regions centered producer. Distance cannot be used as the localization scale for SAGD processes. As the transition zone could be defined by temperature distribution, a new localization function with temperature as localization scale was developed.

The temperature-based localization function was obtained through modifying distance-based localization function. The localization regions were determined through covariance analysis by using a large ensemble. Based on the covariance analysis, the temperature range of the transition zone is determined. The localization function is 1.0 for the regions within this temperature range. Beyond or below this range, the localization function reduces from 1.0 and at the critical or steam temperature the localization function reduces to zero. The localization is applied to covariance of data with permeability, saturation and temperature, as well as the covariance of data with data.

The general localization function was developed by sensitivity analysis with synthetic cases. It could be applied to any SAGD cases with different steam temperatures and reservoir parameters. In the numerical simulation process, the history matching results showed that without localization, the variability in the ensemble collapsed very quickly and lost the ability to assimilate later data with a small ensemble (50 ensemble members) while the prediction was far from the reference with data mismatch remaining at a high level. The temperature-based localization is able to avoid the collapse of the ensemble variability with a smaller ensemble (10 ensemble members) which saves computation time and gives better history-match and prediction results. The computation time was analyzed in the work. With the temperature-based localization the computation time is greatly decreased by 75%. And another approach (localised EnKF with oil saturation) is also applied in this study to compare the calculation rate and accuracy. For this two methods, the localization regions should be the regions that have true correlations with production data. Dynamic data-temperature and oil saturation is used as localization scale in the localization function. And the temperature range and oil-saturation range is defined at which oil is flowing. And critical temperature is defined at which oil begins to get mobile. The localization function is 1 for regions in the temperature and oil saturation range, and decreases to 0 when the temperature reaches the steam temperature or critical temperature, or oil saturation reached initial oil saturation or residual oil saturation. To get the best history matching and prediction results, the localization function is applied to the Kalman gain and covariance matrices separately.
An Integrated Approach for Overpressure Prediction in a Wild Cat High Pressure, High Temperature Exploration Well in Offshore Sarawak, Malaysia
Authors: Chatterjee Avirup , Ghosh Amitava , Bordoloi Sanjeev , Mustapha Anifadora Bt.
Published: November 2016

Pore pressure prediction plays a very important role in well planning as exploration targets is shifting to deeper overpressured reservoirs. Pressure related problems in such zones are mainly associated with narrow operating window resulting in severe well control incidents, sometimes even leading to early abandonment. Uncertainties in prediction models arise from input data, assumptions used in the workflow and the complexity of the geological/structural conditions. It is important to analyse these uncertainties and develop an understanding of the same, prior to drilling so that, various plans and mitigation systems can be put in place.
Case Study on Longitudinally Fracturing Horizontal Wells in the Barmer Hill Porcellinite Rajasthan India
Authors: Nagar Ankesh , Tibbles Raymond , Goenka Sharad Kumar , Guha Rupdip , Chidambaram Prasanna , Sinha Ankaj , Pathak Shashank , Agarwal Prashant , Misra Anurag , Ranjan Amit , Ranjan Vishal , Tiwari Shobhit , Dwivedi Nikhilesh
Published: November 2016

Cairn India Ltd & ONGC completed a joint venture appraisal of the Barmer Hill (BH) field in the Rajasthan block of India in 2015. The objective was to evaluate the effectiveness of horizontal multi-frac completions. The Barmer hill field is a moderate permeability (0.5 – 4 mD) oil bearing porcellanite with alternating sequences of tight shale. To produce this reservoir economically, hydraulic fracturing was the obvious choice of stimulation and was performed on a number of vertical wells (see Shaoul et al. 2007). To better evaluate the development strategy, completions using either transverse or longitudinal fracture treatments were successfully designed, executed, and evaluated. In the appraisal phase, four vertical and four horizontal wells were drilled to appraise the Barmer Hill reservoir in the Mangala field. Two of the horizontal wells were drilled along the maximum horizontal stress direction and completed with multiple hydraulic fracturing stages, which generated longitudinal fractures along the lateral wellbore. The fracture orientation with respect to the wellbore was confirmed with micro-seismic monitoring. This fracture treatment strategy provided the opportunity to decrease the number of frac stages and exhibited lower treating pressures as predicted by standard elastic rock mechanics theory.

While the initial productivity of the transverse fractured wells was expected to be almost 2.5 times more than the longitudinally fractured well, it only produced about 40% more. In addition, the EUR of the longitudinally fractured well is almost the same as the transversely fractured well. Based on the generated fracture geometry, theoretically these longitudinally fractured horizontal wells may also provide better effective sweep efficiency when converted to a water injector from a field development concept.
A Novel Methodology to Optimise the Parameters of Hydraulic Fracturing in Gas Condensate Reservoirs
Authors: Tariq Zeeshan , Al-Hashim Hasan S. , Sadeed Ahmed , Janjua Aneeq Nasir
Published: November 2016

When the pressure falls below the dew point in a condensate reservoir, condensate banking starts build up adjacent to the wellbore, the relative permeability of gas closes to the wellbore badly affected, ultimately causes the reduction in the well productivity index. In these cases, the influence of condensate blockage can be abridged by enhancing the inflow area and attaining linear flow rather than radial flow in the wellbore proximity. These characteristics can only be accomplished by conducting hydraulic fracturing job.

However, the performance of hydraulic fracturing treatment is highly dependent on the operational parameters. Estimation of optimal operational parameters of hydraulic fracturing is typically a difficult job for reservoir engineers. Enhancing the fracture half-length improves the well productivity but this scenario is misleading sometime. Fracture face skin is always associated with the fracture length that may induce additional pressure drop surrounding the fracture and can cause the gas condensate buildup. This happen because as the length of the fracture increases the damage surrounds the fracture cause by permeability impairment also increases, so there must be an optimum fracture length above which increasing the length of fracture is no more efficacious.

This research work presents a new methodology to quantify the amount of fracture face skin associated with the length of the fracture and determine optimum parameter for hydraulic fracturing in a gas condensate reservoir. To achieve the objective of this study a gas condensate simulation model has been created and the parameters associated with the hydraulic fracturing has been deeply investigated, particle swarm optimization has been used as an optimization technique to optimize the parameters that has been investigated.

After optimizing the parameters, the new approach has been proposed that suggests the optimum fracture parameters. This new approach is highly promising and can serve as very handy tool for reservoir engineers to determine the optimum operational hydraulic fracturing treatment parameters for a gas condensate reservoir.
Integrated Study of Core and Image Log for Characterisation and Production Optimisation in Unconventional Basement Reservoir of Padra Field, Cambay Basin, India
Authors: Sarkar Jayanta , Mukherjee Sanjoy , Das Sourav , Bhattahcarya Titas , Kalita Deepika
Published: November 2016

Padra Field, located in the eastern margin of south Cambay Basin, India is known for oil and gas production from unconventional fractured basaltic Deccan Trap. Earlier studies of Padra Trap showed moderately weathered basalt as the reservoir rock. However a thorough study integrating core and high resolution image log for characterizing the volcanic reservoir was yet to be ventured. Fracture modeling on PETREL™ platform was attempted using point data from wells and the resultant model was found to be in agreement with production data from wells. Difficulties faced during fracture coding based on FMI™ data owing to highly scattered fracture dip azimuths necessitated the present study to integrate FMI™ with core data.
Integrated Water Management Challenges
Authors: Al-Shammari H. , Bora A.
Published: November 2016

As reservoirs mature, producing more oil out of maturing reservoirs entails more water production. For maturing reservoirs, it is, therefore, essential for a successful water management process to be introduced – one that can handle substantial volumes of water produced and result in increased oil production.

Water management was not a major concern for Kuwait Oil Company (KOC) in the past. Most of its crude oil production were from Greater Burgan and other oil fields which were producing mostly dry, easy crude with little water production. With the ageing of Kuwait's oil fields, KOC is now experiencing an increase in water production from its maturing reservoirs. This increase is caused by both planned development and field maturity.

Water production impacts the economics of oil field exploitation in number of areas like production volume, corrosions, crude quality, disposal, separation and metering. The accurate prediction of future water production trends is one of the most challenging tasks for KOC. A holistic approach to water management requires working out optimized development plan, enhanced oil recovery requirements, improving sweep efficiency, assessment of future total water injection and disposal needs, and surface handling facility requirements for both oil and water.

Focused multilevel surveillance program, real time data gathering, tracking of water front movement, use of analytical models are part of several techniques used for water injection monitoring techniques to improve water flood conformance in KOC reservoirs.

KOC is currently working an integrated water management plan to improve the overall performance of its reservoirs and establish synergy between different assets to utilize all its resources optimally.
Completion Design for Enhanced Oil Recovery Programs in Brown Fields
Authors: Ibrahim Azhar , Fuzi Nur Azliza Mohd
Published: November 2016

Mature field oil production performance based on conventional field development plan(s) dating back to early 1970s and 1980s is challenged by the inability to fully maximize oil recovery over total field life.

An enabling application that is being widely considered and implemented to some extent in more recent years to address the challenge above is to pursue enhanced oil recovery (EOR) through optimized completion design.

This paper elaborates on several key completion design factors that were evaluated and implemented to enable EOR for two mature fields' offshore Malay basin (Field A and Field B); these key design factors included: Well completion design to maximize zonal production contribution through use of Inflow Control Devices (ICDs) or Interval Control Valves (ICVs) to improve sweep efficiencyFit for purpose well material selection for injectors and oil producers (OP) to last throughout the well lifeOpenhole completion with swell packers and standalone screens to maximize sandface contactApplication of chemical tracer technology to identify water breakthrough for any future zonal isolation plan, zonal contribution estimation and reduce need for wireline intervention to obtain production logging data
Oilfield Corrosion Failures Analysis: Lessons Learned from Pitting Morphologies
Authors: Martin Richard L. , Stegmann Donald W. , Sookprasong P. A.
Published: November 2016

Corrosion of oilfield equipment and processing facilities is a common occurrence that can pose a serious threat to the integrity of the facilities. When failures occur, the leaking substances can be very dangerous to lives and be very harmful to the environment for a long time. Direct total costs due to corrosion, its preventive measures, repairs and litigations are in the billions of dollars each year.

Identifying the type of corrosion is the first step in the analysis and prevention of corrosion-related failures. Visual inspection of the pit morphology can give insights into the type of corrosion that is occurring.

This paper describes how to identify the corrosion mechanism based on the pit orphologies. Descriptions and diagrams of pit morphology of each type of corrosion along with actual pictures of the typical corrosion or failures are included.
The Effect of Shallow Water Demultiple to Prospective Interpretation for Australian Vulcan Sub-Basin of Timor Sea
Authors: Ittharat D. , Taweesintananon K. , Sulaeman E. , Sa-nguanphon S. , Pimthong S. , Wardoyo A. , Guo M.
Published: November 2016

Among major seismic imaging challenges in Vulcan Sub-basin of Timor Sea, Australia, the presence of thick, high-velocity, and faulted Tertiary carbonates in the shallow section overlaid with low acoustic impedance contrast within a soft Cretaceous claystone at the target reservoir makes shallow water multiples the most prominent seismic artifacts in this exploration area. The challenge in this frontier shallow water environment is mainly from inefficient water-layer-related multiples (WLRMs) attenuation. The primary low acoustic impedance at target reflectors are contaminated with short period multiples pose the geological structure uncertainty and incorrect resource and reserve estimation during prospect evaluation process. Unlike conventional demultiple techniques such as Tau-p deconvolution and surface-related multiple elimination (SRME), Shallow Water Demultiple (SWD), developed by CGG, is an efficient tool to attenuate WLRMs in the Vulcan Sub-basin prospect and the result shows significant uplift from the seismic reprocessing project for PTTEPAA.
Improved Oil Recovery Technology Based on Emulsion with SiO2 Nanoparticles and Gelled Acid
Authors: Sergeev V. V. , Kinzyabaev F. S.
Published: November 2016

Results of analysis of reservoir stimulation technologies in carbonate and terrigenous formations, which have been into development a long period of time are presented in article. There were determined main reasons of low effectiveness of bottomhole zone stimulation technologies by compositions that were developed for intensification of oil production (IOP) in depleted zones. Up-to-date classification of physico-chemical methods for reservoir stimulation is presented. Also, results of the analysis of wells operation monitoring (Pashninsky oilfield) after complex reservoir stimulation technology implementation are presented. Based on the monitoring analysis the most effective technologies were educed and determined their disadvantages. Ways of improvement of solutions that applies into complex technology of reservoir stimulation based on invert-emulsion solution (IES) and acid composition were proposed. Based on laboratory test the most effective gelling agents are chosen for acid compositions. Based on different type of emulsions (oil in water emulsion and invert-emulsion) the new water-blocking solutions with SiO2 nanoparticles content were developed.
Drilling Depleting Reservoirs: Case Study from a Bruneian Field on Diminishing Drilling Windows and Stress Paths
Authors: Rai Udai Bhan , Kumar Rajan , Adwani Akash , Fokker Peter , Schoofs Stan
Published: November 2016

There are many cases when operators are forced to deviate from the conventional bottom-up approach for the development of multiple stacked reservoirs, thereby being exposed to the challenges of drilling through depleted reservoirs. The field under study, called Field X in this paper, presents similar challenges with shallow, fault-bounded depleted reservoirs (depletion of several MPa) underlain by (overpressured) reservoirs at virgin pressure.

Reservoir pressure changes (ΔPp) are accompanied by changes in the total principal stresses (Sv = vertical stress, Shmin = lesser compressive horizontal stress, Shmax = greater compressive horizontal stress), characterized by the three stress path coefficients (γv = ΔSv / ΔPp, γshmax= ΔShmax / ΔPp and γshmin= ΔShmin / ΔPp). From drilling perspective, the two horizontal stress path coefficients (γshmax and γshmin) are the key for accurate borehole collapse pressure and fracture pressure prediction in the depleted reservoirs. However, field measurements and theoretical descriptions have focused only on the change in the minimum horizontal stress. Constrained by opportunities for direct measurement and calibration, the changes in the total stresses in the horizontal plane are often assumed symmetric, i.e. γshmax = γshmin. This paper explores the stress path computed for the depleted reservoirs in Field X from full-field numerical simulations and its implications on future drilling activity. The major findings are:

The numerical model suggests significant anisotropy in the two horizontal stress path coefficients.

The model also predicts variations in the two horizontal stress path coefficients with time at different stages of depletion despite a linear-elastic reservoir constitutive model.

The onset of production is defined by a relatively higher γshmin compared to γshmax. This is seen to reverse with a higher γshmax compared to γshmin at the later stages of reservoir development.

These insights on the evolution of horizontal stresses in Field X favorably affect future development options in Field X. The paper discusses the causes and implications of the temporal variations in the horizontal stress path coefficients in Field X, which are also applicable to other small fault bounded reservoirs.
Novel Approach to Repairing Cement Channeling Between Two Reservoir Sand Bodies with Differential Pressure Gradient
Authors: Damasena Edwin , Flew Steve , Ravichandran Narindran , Busaidi Adil , Ambrose Jonathan , Kristanto Tutus
Published: November 2016

Channeling behind casing connecting two sandstone reservoirs in well 13 was suspected due to poor cement job, possibly due to the high angle well of 76 deg. Avoiding communication behind casing between two sands is detrimental for field reservoir management where reservoir pressure maintenance with water injector wells is paramount for continuous production. This paper describes the treatment background, engineering approach, laboratory testing and QA/QC procedures, fluid design stage and job execution using the propriety low viscosity polymer system to seal off channeling behind casing. Cement bond log performed in well 13, a 76 deg. directional well drilled offshore Peninsular Malaysia showed very poor bond behind casing. An injectivity test conducted by setting a retrievable packer in between perforation intervals of the two sand bodies near the suspected channeling confirmed communication between the two sands. Repair alternatives were evaluated opting between cement or polymer gel squeeze. Hydraulic calculation based on the injectivity test result, roughly set the equivalent channel diameter as 0.15 in. Cement squeeze was therefore rejected in view of the small and long cement channel of 109 m. An alternative method to squeeze a low viscosity polymer system into the channel behind casing was hence designed for the purpose of sealing off the channel. The procedure developed was to create a single perforation in between the two perforations in both reservoirs and squeezing the polymer. A retrievable bridge plug and a retrievable packer straddled the squeeze perforation interval and a polymer gel squeezed through the said perforation. After several squeezes each followed by a curing time, pressure tight seal isolating the two reservoir sands was obtained. This was confirmed by setting a retrievable packer above the lower most perforation in the reservoir sand followed by injecting brine while monitoring for returns through the upper perforation, which were none. This unique method, never applied before, to repair a 109 m continuous cement channel between two reservoir sands separated by a thick shale layer using cross linked gel was successful. Two years later the seal is still intact with production from this dual completion well continuing trouble free. The proprietary gel applied is a cross linked low viscosity polymer which cures under downhole temperature to form a tough seal. It is learned that running a retrievable bridge plug and a retrievable packer in tandem in high angle well best not be attempted in future, instead, both should be run separately. Acidizing through the squeeze perforation will assist to improve squeeze pressure. Application of cross linked gel to repair cement channel has been proven to be a viable alternative to cement squeeze.
Methane Leakage Survey Techniques for Environmental Benefits
Authors: Suwagul P. , Borvornyanyong P. , Prakthong P. , Pornsakulsakdi L.
Published: November 2016

It is undeniable that methane is a highly flammable gas having the Global Warming Potential (GWP) of about 21 to 25 times greater than carbon dioxide; therefore, consequences of methane emissions can cause significant concerns to both safety and environment. In 2013 the Infrared (IR) Camera and Hi Volume Sampler had been introduced for effectively identifying and qualifying the methane emissions from company's activities. The methane emission survey campaign had been conducted at the company's oil production facilities located in Kamphang Phet Province focusing on three emission sources: Fugitive, Leaking Compressors, and Pneumatic Control Devices. The emissions detected from these three sources were about 31.5 MMscf per year, equivalent to the GHG emissions of about 15976.1 tonnes CO2eq, and in response to these emissions several mitigation measures have been implemented, including tightening the loose equipment and replacing the worn-out rod packings, during the major plant shutdown after the survey. In total, the GHG emissions have been reduced by 36% or about 5,800 tonnes CO2eq.
Evaluating Lacustrine Shale Oil Reservoirs by Integrating Reservoir Quality and Organic Matter Quality with Advanced Logging and Core Measurements
Authors: Hou Yu Ting , Xi Sheng Li , Wu Yong , Li Huayang , Zhao Xianran , Wu Jinlong , Zhao Haipeng
Published: November 2016

Unconventional reservoirs oil and gas resources have great potential for development, especially in North America, which has been successfully achieved commercial production. Shale oil is one of the unconventional resources. Most of the shale oil reservoirs have complex lithology, poor petrophysical characteristics, complex pore structure, and so on, especially for lacustrine shale oil formation. This paper describes an approach and workflow to characterize the Chang7-3 member shale oil reservoir in the Ordos basin, China by integrating the high tech digital rock physics core analysis data with other special core analysis data to calibrate the reservoir petrophysical properties. The special unconventional core analysis method taken for this project are Tight Reservoir Analysis technology (TRA), Thin Section scanning (TS scanning), Mercury Injection Capillary Pressure test (MICP), N2 and CO2 Gas sorption test, XRD and Nuclear Magnetic Resonance analysis (NMR), and the new logging technology employed are gamma ray spectroscopy logging (LithoScanner*), nuclear magnetic resonance logging (CMR*), dielectric logging (ADT*). The new core analysis and logging technology not only depict the characters of the shale oil reservoir from microscopic to macroscopic scale, but also guarantee to establish the accurate method for reservoir identification and evaluation. The data analysis from above led to the development of evaluation models for organic matter quality and reservoir quality. Analysis of the production data revealed that the hydrocarbon abundance of the Chang7-3 member lacustrine shale oil reservoir is controlled by both organic matter quality and reservoir quality. A production forecast chart of Chang7-3 Member lacustrine shale oil reservoir was constructed based on the organic matter quality and reservoir quality. The application of the developed methodology and workflow achieved very good results and is supported by the test data from multiple wells drilled in the study area.
A New Artificial Intelligence Based Empirical Correlation to Predict Sonic Travel Time
Authors: Tariq Zeeshan , Elkatatny Salaheldin , Mahmoud Mohamed , Abdulraheem Abdulazeez
Published: November 2016

Sonic logs can be used to estimate rock elastic parameters that are useful in obtaining the in-situ stresses of the rock. In cases where the sonic log is missing, the log values are estimated using empirical correlations. Since conducting sonic logging involves time and cost, the industry relies on empirical models. However, none of the available models are universally accepted by log analysts because each model estimates the sonic log values significantly different from the others. The error in sonic log values affects the elastic parameters, which can result in either underestimation or overestimation of the in-situ stresses.

The objective of this paper is to develop simple and accurate model to determine sonic travel time based on gamma ray, bulk density and neutron porosity because these three logs are generally available for every well. Artificial Neural Networks are used for the development of the model. An attempt has also been done to converge the results into one simple empirical correlation using the weights of ANN model in order to make the model equation universal and usable for field applications.

Several empirical correlations from literature were selected and subjected to same real field well log data as the AI model to predict sonic travel time and the results showed that ANN model was able to predict sonic logs with 96% accuracy with a correlation coefficient of 0.96 while other correlations did the same but with lesser accuracy. In addition, the developed empirical correlation from the weights of ANN model gives exactly the same results as predicted by the ANN model.

The developed model along with the empirical correlation can serve as handy tool to help geo-mechanical engineers detremine the reservoir geo-mechanical parameters and design any operation in cases where sonic logs are not available.
Development of an Employer-Based Transportation Demand Management Strategy Evaluation Tool with an Advanced Discrete Choice Model in Its Core
Authors: Hasnine M. Sami , Weiss Adam , Nurul Habib Khandker
Published: November 2016

This paper presents a tool for the evaluation of employer-based transportation demand management (TDM) strategies. The conventional method of evaluating TDM strategies has typically been to conduct expensive before-and-after strategy implementation surveys. As an alternative approach, this research uses a joint revealed preference (RP) and stated preference (SP) survey (the RP–SP survey) administered before deployment of the TDM strategy, which is more cost-effective and efficient. The data collected from the RP–SP survey were used to estimate an advanced discrete choice model, which was packaged into a spreadsheet-based tool for TDM decision support. The tool adopted the concept of penetration rate, whereby only a subset of the target population could be targeted for any specific TDM strategy. The tool that was developed provides an alternative approach for the predeployment evaluation of any TDM strategy for efficient implementation. Moreover, the empirical model used in the tool reveals many behavioral details about commuters’ responses to employer-based TDM strategies.