bluuebunny/crossref_metadata_2025_split huggingface dataset:
Raman Spectroscopy Yields New Discovery of Reaction of Acetic Acid with Calcite
Authors: Qiu X. W. , Chang F. F. 
Published: May 2011

Abstract
Stimulation of high temperature oil and gas wells with HCl could cause significant corrosion to tubular goods. Organic acids are viable alternatives to HCl. However, conventional wisdom teaches that organic acids do not spend to its full capacity due to CO2 in solution. This leads to reducing their carbonate dissolving capacity further. Another potential drawback of using organic acids is the precipitation of the salt of calcium and organic ligands. Consequently, the concentration of the organic acid has to be confined to prevent the precipitation. Due to the above reasons, along with their cost per mass of rock dissolved, organic acids often have limited use in well stimulations.
Recent thermodynamic modeling studies have shown that when an organic acid or a mixture of HCl and an organic acid reacts with calcite, a previously unrecognized reaction occurs. This reaction enhances the calcite's dissolving capacity by the organic acid. The model provided new insight into the reaction equilibrium between organic acids with calcite, and gave a better understanding of which chemical species plays the dominant role in driving the overall dissolution reaction. In the case of acetic acid reacting with calcite, the model found that a chemical species, ca-monoacetate (Ca(CH3HCOO)+), exists because of the association of acetate and calcium ions. This species cannot be ignored. When quantitatively concentrated, it results in higher acetic acid dissolving capacity. Furthermore, mixing acetic acid with HCl can increase the conversion of acetic acid by the same calcium and acetate ion association and lead to more complete spending of acetic acid. The objective of this paper is to present the evidence of the existence of calcium monoacetate through experimental studies using Raman spectroscopy. Results showed that ca-monoacetate does exist during acetic acid dissolving of calcium carbonate. However, quantitative match between the experimental data and thermodynamic model prediction remains uncertain.
Drilling Hazards Diagnosed and Solutions Were Provided to the Northern Iraq Fields Utilizing Geomechanics
Authors: Gao J. , van Galen M. , Chou Q. , Neil B. , Soroush H. , Qutob H. , Mahli Z. , Abalioglu I. 
Published: May 2011

Abstract
The integrity of the wellbore plays an important role in petroleum operations. Hole failure problems cost the petroleum industry several billions of dollars each year. Prevention of wellbore failure requires a strong understanding of the interaction between formation strength, in-situ stresses, and drilling practices. As in-situ stress and rock strength cannot be easily controlled, adjusting the drilling practices is the usual way to inhibit wellbore failure.
Drilling in the problematic Kolosh formation in Kurdistan has always been associated with several wellbore stability problems. This has caused large amounts of non-productive time to drilling programs and the drilling of sidetracks in some of the wells in this field. A review of the drilling reports and dual-caliper logs from offset wells in the area revealed large amounts of washouts in the middle Kolosh section. These indicators demonstrated the requirement for performing a geomechanical modeling and wellbore stability study to mitigate such problems in future drilling operations.
In this paper, local in-situ stress magnitudes, orientations, and formation pressures were characterized. For this purpose, data was analyzed from offset wells (e.g., borehole breakout data, bulk density logs, wireline formation tests, drillstem tests, pressure build-up tests, formation pressure data in this area). The mechanical properties of the formation (including dynamic and static Young's modulus, Poisson's ratio, and rock strength) were evaluated using sonic, density, and gamma ray logs. A rock mechanical properties database and data management software was applied to correlate the calculated dynamic elastic properties to the most appropriate static rock strength and stiffness parameters for a base case wellbore stability model and subsequent sensitivity analyses. 2D elastoplastic and 3D linear elastic models were used to back-analyze the hole collapse and enlargement in the selected offset wells to evaluate and calibrate the geomechanical model. Wellbore stability software was used for this purpose. Finally, a mud weight window was defined, and the optimum profile of the mud weight was recommended for drilling through the Kolosh formations. Due to a narrow mud weight window, additional potential problems were investigated including the possibility of fracturing at the top of Kolosh formation. Finally, relevant solutions were presented.
Innovative In-Situ Reservoir Stress Test Helped to Manage and Optimize Water Disposal under Fracturing Conditions in South Oman
Authors: El Msallati S. , Hammad K. , Priyandoko P. , Cig Koksal 
Published: May 2011

Abstract
One of the major fields in the South of the Sultanate of Oman produces oil at 94% average BSW. All produced water is disposed of without treatment into the same aquifer. The disposed water is injected under fracing conditions and takes place more than 200 m below the lower shale (cap rock) in the sandstone (Fig.1). However the failure of the field's cap rock could result in oil deferment and the contamination of the overlying aquifer; therefore rigorous risk management is strongly required.
Several in-situ stress testing (mini-frac) stations were conducted in the field focusing on lower shale and sandstone formations to evaluate the risk of breaking the cap rock and above formations associated with the water disposal. However this was very challenging using the normal ways of testing; hence the stress testing application was conducted with an oil based viscous fluid. The viscous fluid allowed accomplishing the objectives in higher permeability and shale zones. The oil based viscous fluid facilitates initiation of a fracture in highly permeable sandstone formations and reduces the osmosis and plastic behavior effects in shale zones.
The viscous fluid stress testing provides the results required to update the numerical models for each formation by obtaining minimum stress and fracture initiation, propagation, and closure pressures (frac gradients). Moreover the test results will help to build models that can predict fracture growth while injecting water.
This paper will discuss in detail the viscous fluid stress test and how the results can be used to understand the reservoir behavior. Realistic injection forecasts were made possible using commercial fracture simulation software and some analytical and diagnostic methods based on pressure survey and injection volumes history.
Deblending the Simultaneous Source Blended Data
Authors: Huo Shoudong , Tsingas Constantine , Kelamis Panos , Xu Hai , Pecholcs Peter 
Published: May 2011

Abstract
Recently, the concept of simultaneous source acquisition (Berkhout, 2008; Beasley et al., 1998) showed that can significantly enhance field acquisition efficiency and at the same time due to the increased seismic data sampling improves seismic image quality. In 2010 Saudi Aramco by employing a fixed active super spread continuously recorded 18 single vibrators operating simultaneously in 18 separate quadrants. During this test over 45,000 vibrator points were acquired in 24hr field operation. The source blended acquisition field test aimed in the optimization of the following field acquisition parameters: high source density, unique up-sweep length and source distance separation. For blended data since all the sources were acquired at different times, the characteristic of interfering noise appears random in certain data sorting domains such as the common-receiver, common-offset, cross-spread and CMP. Stacking and migrating the blended seismic data without any further denoising produces acceptable results as stacking can effectively suppress random energy. However, additional efforts towards crosstalk separation have been proposed so that deblended pre-stack data can be further processed for amplitude and reservoir characterization analysis. In this paper, we illustrate suitable processing techniques and workflows in order to attenuate source interference noise so that the simultaneous sources can be separated effectively into equivalent data sets for further pre-stack processing. Comparisons with conventionally acquired 3D seismic data in the same area are also presented.
Optimizing The Planning, Design And Drilling Of Extended Reach And Complex Wells
Authors: Agbaji Armstrong Lee 
Published: May 2011

Abstract
Extended Reach Drilling (ERD) is an integrated methodology for drilling high-angle wellbores with long horizontal displacements. Several problems are associated with extended reach wells. Thus for high levels of performance improvement to be achieved, it is essential to analyze the interrelationship among the elements involved in the entire drilling process. This is because a system that considers the individual elements of the drilling system in isolation is inadequate to deliver desired performance improvement.
In this study, an algorithm that sets forth a design for a drilling program that is suitable to drill an extended reach well was developed using Visual Basic. Although the algorithm touches on several factors affecting extended reach drilling, the major focus is on the six elements, which are considered the critical factors. These are: Well Trajectory Design, Bottom Hole Assembly (BHA) Design, Bit Hydraulics, Drill String Design, Torque and Drag, Hole Cleaning and ECD Management. The proposed algorithm evaluates the interrelationship among these critical factors and provides direction on the processes and tasks required at all stages in the design and drilling of an ERD well to achieve maximum drilling performance. The development of the model is based upon information gathered from several sources, many new ideas from technical publications, along with information and feedback from field-based personnel. The output generated from the model compare well with results from actual field data.
Recovering Flowing History from Transient Pressure of Permanent Down-hole Gauges (PDG) in Oil and Water Two-Phase Flowing Reservoir
Authors: Shiyi Zheng , Fuyong Wang 
Published: May 2011

Abstract
Permanent Down-hole Gauges (PDG) have been widely installed in oil and gas reservoirs. These systems monitor the real-time down-hole information continuously. In this way, real time reservoir management and production can be significantly improved.
The key in analysing long term transient data from PDG is the flowing rate history. Accurate flowing rate history is not always available in oilfield, especially in the multiphase reservoir. The multi-phase flow meters are not only expensive but also inaccurate and unstable. The common practice is that several wells are measured together through manifold, and total cumulative production is given without flowing rate details for each individual well. How to recover accurate flowing rate history is a challenge for reservoir engineers.
This paper presents the study results of recovering flowing rate history using the Wavelet Transform (WT) method in oil and water two-phase flowing reservoir. At first, the transient pressure from PDG is processed by HAAR wavelet. The WT will yield frequency amplitude changes when flow events happen, so the time of flow events will be identified. Then, with the relationship between liquid rate change and the corresponding WT frequency amplitude changes, the flowing rate history can be recovered with high accuracy.
The developed algorithms were demonstrated through two kinds of simulation models, i.e., constant water cut and increasing water cut after water breaking though. In addition, the relationship between water cut change and WT frequency amplitude is developed. The effects of skin, wellbore storage and reservoir heterogeneities are considered, and the study results have demonstrated the robustness of this method and its promising future application in practice.
Effective Reservoir Management Strategies to Revitalize Dead Producers Behind the Flood Front
Authors: Abuhassoun Amer H. , Sequera Bernabe A. 
Published: May 2011

Abstract
Saudi Aramco has employed horizontal sidetracking on existing dead vertical wells to enhance wells’ productivity and rejuvenate field's performance. Understanding flood front movement, inter-reservoir connectivity, and pressure propagation in a highly stratified clastic reservoir in mixed fluvial and aeolian depositional environments are the key parameters that led to successful deployment.
This paper will present a case example discussing development strategies to revive an idle vertical well that was shut-in due to high water cut and low oil productivity. Both dynamic and static data were integrated to describe fluid flow phenomenon in the area to provide better understanding of the geological model, sweep and oil recovery. The multidisciplinary study indicated lateral and vertical reservoir heterogeneity and multilayer reservoir compartmentalization that caused uneven flood front movement and inadequate pressure support.
The team has considered all the uncertainties involved and have formulated an optimum completion plan. The team recommended sidetracking the idle well about 1 km away to target a sweet spot through an aggressive step-out strategy. This long step-out strategy was the first to be implemented in this sandstone reservoir where risk of hole collapse or stuck pipe is extremely high. Prudent reservoir monitoring and applying safe drilling and mud management practices were the major elements to successfully achieve the objectives. The plan was carefully executed by deploying fit-for-purpose completion that consisted of premium sand screens and blank pipe with mechanical packers to isolate a wet zone. The well was then treated with a clean-up fluid to remove any mud filter-cake to enhance productivity. The current production performance exceeded expected rate by 100%. The success and the captured lessons-learned from this strategy will be capitalized on for implementation in future similar sidetrack opportunities.
A New Nuclear Method to Locate Proppant Placement in Induced Fractures
Authors: Duenckel Robert J. , Smith Harry D. , Chapman Mark A. , Saldungaray Pedro 
Published: May 2011

Abstract
Traditional proppant placement evaluation in hydraulically induced fractures utilizes detection of radioactive tracers pumped downhole with the "frac" slurry. Although this technique has proven useful, it involves environmental, safety, and regulatory concerns/issues. The fracture height determination method described in this paper eliminates downhole placement of radioactive materials. A high thermal neutron capture compound (HTNCC) is inseparably incorporated into each ceramic proppant (CEP) grain during manufacturing in sufficiently low concentration that it does not affect mechanical strength, conductivity, durability, or density of the particles. The proppant is detected using standard compensated neutron logging tools (CNT) and/or pulsed neutron capture (PNC) logging tools, with detection based on the high thermal neutron absorptive properties of the compound relative to downhole constituents. Since the HTNCC is placed permanently in the proppant, logging for proppant detection can occur at any time(s) after the frac job, with no requirement for special handling or mixing considerations. To clarify, the new detectable proppant is not radioactive, and the benign detectable material is uniformly mixed into the ore during proppant manufacturing, so there is no chance for segregation of the detectable agent from the proppant.
Specifically, the proppant is detected using after-frac CNT logs, sometimes combined with corresponding before-frac logs. The increased thermal neutron absorption by the HTNCC reduces count rates in the near and far detectors, with approximately the same percentage reduction observed in each detector, leaving the near to far detector count rate ratio (N/F ratio) unchanged. One detection method utilizes a comparison of before-frac log count rates and after-frac count rates, with reduced after-frac count rates observed in zones containing proppant. Another detection method, especially useful if formation gas saturations change, requires only the after-frac log. Since the N/F ratio is essentially unaffected by proppant, after-frac count rates predicted from the ratio will also be unaffected. These synthetic count rates will be greater than the observed after-frac count rates in intervals containing proppant. When PNC tools are utilized in a third method, tagged proppant can be identified from count rate suppression in the detectors and also from increases in the measured formation and/or borehole component capture cross sections. In tools utilizing spectral gamma ray detectors, the HNCC may also be detected using capture gamma ray spectral deconvolution.
Monte Carlo modeling data are presented demonstrating the utility of these techniques employing CNT tools. Field examples illustrating proppant detection using compensated neutron tools are also presented.
The Aramco Method – Its Drilling and Production Engineering Significance
Authors: Amanullah Md. , Bubshait Abdulaziz , Allen Tim , Foreman Darrel 
Published: May 2011

Abstract
A new laboratory method defined as the ‘Aramco Method’ developed by Saudi Aramco Scientists can play a pivotal role to reduce the mud related formation damage, enhance the oil and gas production and improve the return on investment. The experimental results produced by the method will provide a comparative assessment of the relative stability of different sized bridging materials that are available for non-damaging drill-in fluid formulations. The method provides a useful tool to select the most suitable and highly durable bridging material for designing and developing superior drill-in fluids to eliminate or reduce mud related formation damage while drilling.
Preliminary experimental results produced by the method using a commercially available sized bridging material indicate significant variation in the PSD (particle size distribution) curve of sized bridging materials after testing due to the attrition effect and thus indicate a change in designed particle size distribution in down hole conditions. Material showing significant variation in the PSD due to the attrition effect during the test has the highest potential to cause formation damage. In case of low attrition resistant sized bridging material, there is a need to discard significant volumes of drilling fluid and to build fresh fluid in order to add new sized bridging material in the drill-in fluid system frequently to restore the desirable particle size distribution. On the other hand, material showing no or negligible variation in the PSD due to high resistance to attrition damage has the lowest potential to cause formation damage. Due to the preservation of the PSD of high attrition resistant bridging material for a long time, the drill-in fluid containing such material needs only infrequent addition of additional sized bridging material in the drill-in fluid system to maintain the desirable particle size distribution and eliminate or reduce the formation damage potential of the drill-in fluid. The engineering significance of the method is that it will provide a guiding tool to select the most suitable sized bridging material to reduce the formation damage potential of drilling mud while drilling and improve the well productivity while producing. The economic significance of the method is that it will reduce the mud management cost and enhance the return on investment by improving the ultimate recovery of oil and gas resources
Cementation Exponent Estimation for Complex Carbonate Reservoirs Using a Triple Porosity Model
Authors: Al-Ghamdi Ali , Aguilera Roberto , Clarkson Christopher R. 
Published: May 2011

Abstract
A previously defined triple porosity model is used to calculate the cementation exponent (m) of complex carbonate reservoirs in the Middle East using well log data. The cementation exponent is usually affected in carbonate rocks by different types of primary and secondary porosities. A combination of interparticle porosity, non-connected porosity (e.g., vuggy and fenestral) and fractures increases the uncertainty in the estimation of m. Therefore, a well-defined petrophysical approach must start by first understanding the rock's fabric.
Initially, samples are classified into different flow units based on pore throat apertures at 35% cumulative pore volumes (rp35). This classification is then extended to include variations in porosity types based on geological and petrophysical descriptions of each rock. Each sample has different proportions of connected and non-connected porosities. These porosities are defined as matrix, fractures and non-touching vugs (including fenestral porosity). The porosity types are extracted from well logs for the whole reservoir section and are cross-checked against core samples and thin sections.
The value of m in a triple porosity system can be larger, equal, or smaller than the cementation exponent of only the matrix blocks (mb). This variation depends on the relative contribution of natural fractures and non-touching vugs compared to the composite triple porosity reservoir. A continuous curve of m values is obtained using this model. A good comparison has been obtained between the results of this model and m values measured in the laboratory.
Estimation of variable m values within short distances in a given reservoir using the triple model is a significant development in formation evaluation that helps reduce uncertainty in petrophysical calculations. The results increase the confidence level in water saturation and reserves determinations.
Opportunities/Lessons Learnt and New Technologies for Redevelopment of a Mature Field
Authors: Trebolle R. , Hamdan V. H. , Sepulveda W. , Whitney P. , Grigorescu R. , Mohammad Afzan , Kadir F. A. , Tusimin F. Bt. , Curteis C. 
Published: May 2011

Abstract
In general, mature oilfields have a good portion of the remaining reserves still trapped due to inefficient drainage, production decline, increase in water cut and sand production and aging of the existing systems. This paper addresses techniques and initiatives to optimize development plans in a mature field. For Bokor Field in particular, there have been identified and implemented opportunities such as Infill drilling and workover optimization, dynamic underbalance perforation (DUP), matrix acidizing and propellant stimulation, water shut-off mechanical (WSOM), sand management, through tubing stand alone screens, deployment of electrical submersible pumps (ESP) and gas lift NOVA valves, real time surveillance (DHG, DTS and LiftWatchers*) and optimization, and microbial EOR.
Before the implementation of these techniques, this field had a daily oil production equivalent to 10 MSTBD (after fields decline) and the current production is 26 MSTBD. The two main reason for this increase are: New technologies were employed in this oil field with dramatic results incorporating new hydrocarbon reserves, via 3D seismic techniques, high resolution stratigraphy and better static and dynamic simulation models.Multidisciplinary integrated studies to increase field ultimate recovery factors by improvements in drilling, workover, stimulations, facilities and EOR methods.