bluuebunny/crossref_metadata_2025 huggingface dataset:
Bandwidth Estimation Tools and Techniques: A Review
Authors: Airon Mukta , Gupta Neeraj
Published: October 2017

Wireless communication has proliferated due to the colossal augmentation of smart phones, mobile phones, tablets and laptops etc. Multimedia applications such as live videos, audios, still images, animated graphics and live communications all requires accompaniments of quality of service (QoS) as well as reliable end-to-end transfer of data. Information about the availability of resources in channel is must in order to improve the QoS. QoS can be determined in terms of capacity of channel, available bandwidth (ABW), and bulk transfer capacity (BTC). Bandwidth availability is a key check for improving the QoS in a network. The performance of a multimedia application is directly affected by the bandwidth availability. One of the most important QoS characteristic is ABW at a wireless route and it can be demarcated as least unused capacity of links instituting a network route. Since now there have been many bandwidth estimation techniques are available in the literature to increase the network performance. Bandwidth estimation techniques have been arranged into three leading classifications: i) Active probing bandwidth estimation techniques, ii) Passive bandwidth estimation technique and iii) Model based bandwidth estimation techniques. Each of these techniques are briefly discussed in this paper.
Environmental Inequality in China: A ‘Pyramid Model’ and Nationwide Pilot Analysis of Prefectures with Sources of Industrial Pollution
Authors: He Qi , Fang Hong , Ji Han , Fang Siran
Published: October 2017

In China, environmental pollution generated via industrialization as well as the profound changes in the social structure and gradual maturation of the social hierarchy have jointly contributed to the Chinese people's increased environmental consciousness and appeals for environmental justice (EJ). Because of the absence of an EJ theory and a lack of empirical research focused on China, this paper proposes a ‘Pyramid Model’ for China’s EJ research that involves the following three factors: basic demographic and socioeconomic factors, U.S.-based EJ principles, and Chinese characteristics. A nationwide pilot analysis of environmental inequity at the prefecture level is conducted by empirically studying the association of demographics and socioeconomic status with sources of industrial pollution in China. The prefecture-based results are shown to be robust and indicate that areas inhabited by ethnic minorities and western regions in China carry disproportionate environmental burdens. However, a different picture for migrants is presented, revealing that Chinese migrants are not currently exposed to greater levels of industrial pollution, and relevant interpretations of these findings are provided. The results also show that environmental inequality associated with income level, which is observed in the U.S., does not occur in China.
Multiscale Modeling of Carbonate Acidizing Using Continuous Time Random Walk Approach
Authors: Kang Kang , Abdelfatah Elsayed , Pournik Maysam , Shiau Bor Jier , Harwell Jeffrey
Published: October 2017

Matrix acidizing is an extensively used stimulation technique to improve oil recovery in carbonate reservoirs. The interplay between transport and reaction of acid is highly affected by heterogeneity at different scales. The existing experiments and models have difficulties to capture effect of heterogeneities across pore-scale, core-scale and field-scale. The objective of this paper is to provide an efficient multiscale model using continuous time random walk approach to predict acidizing behavior at macroscopic scale considering the effect of microscopic scale heterogeneity.

Instead of solving traditional advection-diffusion-reaction equation (ADRE), the continuous time random walk (CTRW) incorporating with particle tracking (PT) is a probabilistic approach to model fluid transport in heterogenous porous media. Here, the CTRW-PT describes motion of acid particles as random spatial and temporal increments at pore scale which follow independent distributions whose characteristic probability density functions (PDF) are derived. The transport of acid particles is simulated by particle tracking first and chemical reaction is included using the midflight approach. CTRW-PT simulation yields macroscopic plume of acid which creates wormholes at core scale. The core-scale wormhole propagation at different injection rate and concentration agrees qualitatively with the experimental results. Nevertheless, CTRW-PT also demonstrates the effect of heterogeneity that may increase the minimum pore volume to breakthrough. Using CTRW-PT approach is more efficient than solving ADRE in large-scale modeling.

The utilization of CTRW-PT approach on acidizing modeling captures the wormhole propagation of hydrochloric acid in limestone cores. This probabilistic and stochastic approach provides an efficient way to model carbonate acidizing and one can consolidate the lab-scale understanding with field prediction to optimize the acidizing treatment design.
Core Characterization and Numerical Flow Simulation in Representative Rock Types of the Raudhatain Field in Kuwait
Authors: Dernaika Moustafa R , Sahib Mohammad Raffi , Gonzalez David , Mansour Bashar , Al Jallad Osama , Koronfol Safouh , Sinclair Gary , Kayali Anas
Published: October 2017

Detailed core characterization is often overlooked in the sampling process for core analysis measurements. Random core sampling is usually performed and the selected plugs are not associated with rock types or the reservoir heterogeneity. The objective of this study is to obtain representative samples for direct simulation of petrophysical and fluid flow properties in complex rock types.

A robust sampling strategy was followed in reservoir cores from two successive heterogeneous carbonate and siliciclastic formations in the Raudhatain field in Kuwait. The sample selection criteria were based on statistical distribution of litho-types in the cores to ensure optimum characterization of the main reservoir units. The litho-types were identified based on porosity and mineralogy variations along the core lengths utilizing advanced dual-energy X-ray CT scanning. High resolution micro-CT imaging and subsequent segmentation provided 3D representation of the pore space and geometric fabric of the core samples. Primary drainage and imbibition processes were simulated in numerical experiments using a pore-scale simulator by the Lattice Boltzmann Method. Capillary pressure (Pc) and relative permeability (Kr) curves together with water and oil distributions were investigated for complex geometries by the different rock types.

The dual energy CT density was compared with wireline log and provided accurate calibrations to the downhole logs. The different rock types gave distinct capillary and flow properties that can be linked to the rock structure and pore type of the samples. The Lattice Boltzmann based pore-level fluid calculations provided realistic fluid distributions in the 3D rock volume, which are consistent with pore-scale physical phenomena.

This characterization method by the dual energy CT eliminates sampling bias and allows for each cored litho-type to be equally represented in the plugs acquired for subsequent petrophysical and fluid flow analyses. It also provides accurate calibration tool for downhole logs. The digital analysis gave reliable SCAL data with improved understanding of the pore-level events and proved its effectiveness in providing advanced interpretations at multiple scales in relatively short timeframes.
Stimulation of High Temperature Carbonate Reservoirs Using Seawater and GLDA Chelating Agents: Reaction Kinetics Comparative Study
Authors: Abdelgawad K. Z. , Mahmoud M. A. , Elkatatny S. M.
Published: October 2017

Hydrochloric acid (HCl) as a stimulation fluid of deep oil and gas carbonate reservoirs is very common practice in the industry. Using HCl acid during matrix acid treatment in carbonate acidizing has the limitations of; rapid tubulars corrosion, formation face dissolution due to fast uncontrolled reaction rate especially at high temperature reservoirs and low injection rates, and induced formation damage due to sludge formation in presence of crude oil with high asphaltene content. There is also a difficulty of using HCl in stimulating multilateral and horizontal wells due to its fast reaction with the reservoir rock. With the intensive care given to the environment in the 21 century, chelating agents were introduced as alternatives to HCl to alleviate the problems associated with HCl. GLDA (Glutamic acid diacetic acid) chelating agent was used previously to stimulate carbonate reservoirs at high pressure and high temperature (HPHT) conditions. GLDA was prepared in fresh water to stimulate these reservoirs.

In this paper, the effect of dilution using seawater on the reaction kinetics of low pH GLDA (3.8 pH) with different carbonate rocks under HPHT conditions was investigated using the rotating disk apparatus (RDA). The reaction experiments of GLDA solution with carbonate rocks in both fresh (GLDA/DI) and seawater (GLDA/SW) were carried out at the same conditions. Indiana limestone and Austin chalk carbonate rock samples were used to investigate the effect of rock facie on the reaction.

The reaction regime of GLDA chelating agent with calcite is identified to be mass transfer limited in both seawater and fresh water. Also the overall reaction rate and calculated diffusion coefficient showed a high dependency in the temperature. At 200°F and 1000 psi the diffusion coefficient calculated for the reaction of GLDA/SW with Austin chalk is an order of magnitude higher than the reaction of the same fluid with Indian limestone.

The reported diffusion coefficients can be used to simulate for the optimum injection rate required for stimulating high temperature carbonate formation. Highlighting the effect of porosity facies in the acid reaction with carbonate rock will lead to better understanding of the overall reaction of stimulation fluids with carbonate rocks of the same lithology but different porosity facies.
Protecting Offshore Oil Terminals from Wave Action using Innovative Floating Breakwaters
Authors: Neelamani S..
Published: October 2017

Loading into or unloading of oil and gas from very large crude carrier (VLCC) normally happens in the open sea, since water depth of about 18 to 22 m are needed for such vessels, and ports to accommodate such vessels are not available everywhere. For example, in Kuwait, oil loading terminal is located at a distance of 12 km from the coast at a mean water depth of 20 m. The waves at this location are predominantly approaching the mooring vessels from northwest and southwest and are moderate most of time, with wave heights less than 1.0 m for more than 85% of the time in a year. Wave height exceeds more than 2.0 m for up to 15 days in a year. During such wave climate, oil loading operation is risky. Stopping one day of oil loading operation means revenue loss of about 100 million US $ to the country. Hence it is required to reduce the wave climate around the loading terminal. Construction of any fixed wave barrier like offshore rubble mound breakwater will be out of question for few reasons. It will be prohibitively expensive (for example, each m run of the offshore breakwater will consume more than 1000 m3 of stones, which will cost about 20,000 KD/m run and hence for say 1000 m length of an offshore rubble mound breakwater, it will cost about 20 million KD); presence of such fixed structure is a navigational hazard; reorientation is not possible when the incident wave direction changes significantly from one season to another season. Kuwait Institute for Scientific Research has carried out studies on Floating breakwaters (FBW). The wave transmission and mooring forces were measured for a wide range of wave conditions. Studies were carried out on conventional pontoon breakwaters and then on FBWs with different number of skirt walls fixed at the keel of the pontoon FBWs. Wave transmission is found to be reduced significantly (to the order of 25% to 60%) by adding three or five skirt walls.

However, mooring forces are increasing to an extent of 20% to 30%. A basic design and cost analysis is carried out for the floating breakwater and is compared with the rubble mound offshore breakwater. For the floating breakwater with skirt walls, the volume of material required is less than 10% of the material for rubble mound breakwater and cost saving to the tune of 50% to 70% is possible. The cost for construction and installation of such floating breakwater for 1 km length will be about 3 million KD, which is about 10% of the earnings/day of export operation. The results of this study can be used for cost effective design of floating wave barriers and loading of crude oil can be done for the whole year with less risk induced by the wave actions.
Production Optimization from a Short Lateral Horizontal Well in a Braided Fluvial Deposition System: A Case Study from Greater Burgan Field, Kuwait.
Authors: Naik Vinay , Bahman Hussain , Al-Haddad Saud , Ali Farida
Published: October 2017

Greater Burgan Field has been producing from more than 60 years and brings many challenges. The majority of the production comes from Wara and Burgan reservoirs. The Cretaceous Burgan sands are divided into five main reservoirs; two reservoirs consist of stacked, massive fluvial channels, while remaining three mostly consist of delta distributary channels and bays in a tidal delta setting grading to shallow marine. BGSM reservoir is one of the five reservoirs of Burgan reservoirs, which is deposited mostly by braided fluvial systems and is one of the major producers of the Greater Burgan Field. Some of the areas where remaining oil column of BGSM reservoir has become less; the optimization of production has been a challenge. This is due to the fact that due to less oil column; the production shortly becomes water wet and well ceased to produce by vertical or deviated well.

To produce from BGSM reservoir, one horizontal well was drilled in a low potential area for the first time where nearby wells were water wet with short self-flow production life. The planning of this well required to complete the well on the top of reservoir with short later section. To assess the potential of this area, a pilot well drilled and which confirmed around 35 ft. of remaining oil. Based on this horizontal well was planned and drilled with a short lateral. Geo-steering services was used throughout the landing and lateral sections while drilling. The Open Hole Horizontal section completed with 5 1/2″ completion equipment with 26 ICD zones.

The well was drilled successfully with a short lateral of around 650ft. and was completed on top of BGSM reservoir with 5 ½" Advance ICD in open condition with an option to produce in future in BGSU2 reservoir. The well is producing with sustained production of 1200 blpd with 12% water cut for the last one year. The well started to flow to the gathering center with high wellhead pressure.

For the first time horizontal well drilled in a low potential area of BGSM reservoir. The well drilled successfully with an advanced ICD completion. Also for the first time Advanced ICD's where sliding sleeves in BGSU & part of massive BGSM sand were lowered in closed condition (could be opened in future by rig less CTU operation) whereas lowered in Open position in another BGSM Interval which is structurally at higher position and at hill side of the lateral section. The well is producing with sustained production rate and minimum water cut percentage for the last one year. This process will help in future to benefit for all types of horizontal producer wells.
Regional Variations in Water Quality - A Key Factor Influencing Water Injection
Authors: Badusha S.. , Al-Tahou Y.. , Qamber A.. , Al-Jasmi A.. , Juma M. A.
Published: October 2017

Natural dumpflood injection is used for pressure maintenance in a good channel sand holding considerable reserves. The layer is on depletion drive with very weak aquifer support. Natural dumpflood injection was modeled based on success in a similar layer in an adjacent field. Due to the high mud weight used during drilling, the layer is usually damaged. Dumpflooding experience in the analogue field suggests that injection is initiated only after matrix acid stimulation. Therefore, it was not a surprise when the layer did not take in any water initially. However, once the usual stimulation attempts did not achieve the desired results, possible causes and alternates were evaluated.

A comprehensive lab study was designed to assess all the potential problems associated with injection. Fluid-fluid interaction issues like scaling, possible formation of oil-in-water emulsion, fluid-rock interaction such as clay swelling, fine migration related to water incompatibility, all impacting efficiency of water injection on oil mobility and recovery were studied. To simulate every possible field condition all the major water sources were sampled and taken for study. For fluid rock interaction studies, core plugs from the layer was used.

Scale tendency was studied using Jar test and predictions at reservoir conditions were made through ChemScale software. The scaling products from Jar test was analyzed with SEM confirming the results. Routine core analysis was performed to measure porosity and permeability in the coreplugs. XRD was done to understand the mineralogy of the layer. After measuring the baseline permeability, the plugs were subjected to flooding with source waters. One set of coreplugs were fully saturated with target water and flooded with source waters. Flooding was repeated on core plugs saturated with oil at irreducible water saturation until it reached residual oil saturation. An investigation of emulsion formation was conducted between oil and source waters. Study results gave an indication of many potential issues like self scaling tendency of source waters and permeability reduction due to fine migration and scale formation. Out of the many factors, the presence of considerable concentrations of sulphate forming cations was identified as the primary issue to focus on. Sulphate reducing chemicals are being evaluated for injection along with the source water.

Injection water quality is one of the primary factors to consider for effective injection. This is even more crucial in case of dumpflooding, wherein water is sourced from sub-surface. Due to the wide extent of the field and possible diagenesis effect there could be regional variations in water quality. Due diligence needs to be paid to these regional variations in water quality and choose prudently among alternate source water reservoirs.
First Successful Multistage Completion Paves the Way for Optimized Field Development of the Jurassic Formations of North Kuwait
Authors: Ahmed Zamzam , Al-Otaibi Yousef , Bloushi Taha , Fidan Erkan , Sharma Siddhartha , Pradhan San Prasad , Al-Mutairi Mubarak , Al-Failakawi Abdul Aziz , Shaikh Ahmed Karim , Quint Edwin
Published: October 2017

The HPHT, sour, deep, fractured and not so fractured carbonate Jurassic formations within the North Kuwait cluster of fields present extraordinary challenges in driving towards an optimized field development that maximizes liquid recovery and meet the gas production aspirations for the state of Kuwait.

The Middle Marrat reservoir has been developed to date with cased and perforated liner completions across the 500- 700ft pay. However due to the high permeability contrast between the different reservoir flow units, the low permeability zones are typically not contributing. This is further exasperated with the inability to effectively acid stimulate large proportion of the net pay with a single stage bullhead treatment especially when the contrast in permeability between the various flow units is higher than one order of magnitude.

Key to successful reservoir management of the Middle Marrat whilst maximizing well capacity to meet the production aspirations is to implement a completion and stimulation strategy that maximizes flow contribution from as much of the net pay as possible. Single stage bullhead matrix acid stimulation treatments like those executed in the past will only stimulate the top decade of permeability. The current 4-1/2" cemented completion ‘plug and perf’ standard will require intensive well intervention to set and drill out plugs in order to selectively stimulate individual zones.

To develop an alternative completion and stimulation strategy for developing Middle Marrat, the first 4-1/2" multistage ball activated sleeve completion system has been deployed successfully in a Middle Marrat deviated development well. 2 out of 3 stages installed have been acid stimulated and flow tested showing excellent results. The operational experience and learnings acquired from the project have provided the necessary confidence to the organization to deploy the technology in tight gas and unconventional reservoirs within North Kuwait, but also challenge the existing cemented ‘plug & perf’ completion and stimulation approach for the development of the more conventional Middle Marrat reservoirs.
Successful Installation of 1st 15K Multistage Completion System in North Kuwait Gas Well
Authors: Al-Mutairi Abdulaziz , Baqer Hussain Ali , Dhabria Akshaya Kumar , Rook Gert-Jan , Shaik Ahmed Karim , Al-Mutairi Bandar , Hii King-Kai , Hadi A. A.
Published: October 2017

The optimum development of the Deep Carbonate reservoirs in North Kuwait is key to achieve KOC's gas production targets. To optimize (future) production and accessibility of the various Flow Zones within the Target MT formation, KOC has selected a 4.5" mono-bore design to complete the North Kuwait Gas wells. To further improve understanding of production contribution from different flow zones and to enable selective stimulation and effective testing of flow zones, a trial was conducted in a new well to install a 4.5" 15K rated open-hole Multistage Completion (MSC).

The well trajectory was designed with all directional work done before the reservoir section. The deviated reservoir section was drilled successfully to the planned TD. A three stage MSC with a long tail string (for future access to deeper reservoirs) was successfully installed. The bottom and middle stages were successfully stimulated and production tested. Stimulation and testing of the upper stage is planned for the future.

To build on the success of this first trial another candidate well has been identified and a second 15K MSC system is expected to be installed in the second half of 2017.

This paper describes the best practices and the learning in planning and installation of a first successful open-hole MSC in a High Pressure gas well in Kuwait, as well as recommendations for future MSC installations in deep high pressure gas wells with large variations in reservoir caracteristics.
Experimental Evaluation of the Swelling Behavior of Unconventional Shale Formation at and Near the Wellbore in the Presence of Various Drilling Fluid Systems
Authors: Alouhali R. A. , Soliman M. Y. , Emadi H.. , Amanullah M..
Published: October 2017

No two shale plays are the same. Experimental and field data shows that shale formations act differently when exposed to similar conditions. The instability of shale formation is considered one of the major problems facing drilling operations. Bit balling, cutting dispersion, washouts, and stuck pipes are some of the problems faced when drilling shale formation. Only recently, shale formation became a target for hydrocarbon production. Shale plays are the new frontier for drilling and development. When the oil price was high, it was economical to drill and produce from shale formation. Now that the price of oil is relatively low, drilling and producing from shale formation might not be that lucrative. To reduce the cost of developing shale plays, we need to understand the producing shale geomechanical properties. There have been many studies on conventional shale formation and it has helped reduce potential drilling problems in those formations. However, not all shale formations are the same, and solutions that worked with one will not necessarily work with others. That is why we need to conduct studies focused on producing shale. Two producing shale formations were used in this study they are Marcellus shale and Arabian Peninsula (AP) shale. This study is exploring the difference in swelling behavior between the one side of shale core sample that is in direct contact with fluid with the other side of shale that is not in contact with drilling fluid. This is meant to represent the swelling at the wall of the wellbore and the swelling near the wall of the wellbore. Six samples from Marcellus shale and six samples from AP shale were used in this study. Two samples from each formation were used to collect the mineralogy data using XRD/XRF tests and the remaining four samples were used in the swelling tests. For the swelling tests, the samples were half submerged in various drilling fluids where half of the core sample is inside the fluid and the other half hangs above the fluid level. Strain gauges attached to both side collect the swelling behavior continuously for seven days. Results shows that at low swelling levels the back side of the wellbore (near well bore) shrinks while the wall of the wellbore swells. However, at high swelling rate both the wall of the wellbore and near the well bore increase in size following a similar swelling profile.
Well Integrity in the Times of ISO 13679 and Premium Connections: Experiences and Way Forward
Authors: Grijalva O.. , Perozo N.. , Holzmann J.. , Paz C.. , Oppelt J..
Published: October 2017

Developments in OCTG connections defining well integrity and mechanical performance of oilfield tubulars are not something newas a continuous feedback between field challenges and theinnovative nature of the Industry is something derivated into newer, more intensive Full Scale Testing procedures and novel analytic tools for connection performance evaluation in the last decades. The relationship between all those factors has been condensed in the present paper which gives shape to a comprehensive "technical history" for Premium Connections, hidden and scattered so far in issued patents, manufacturer manuals, brochures and selected field cases generated between 1935 and 2017.

Design schools can be well defined by manufacturer and region;apart from this, theadvancements in testing and manufacturing made possible to adjust the connection to the technical constraints put fromthe field, namely a high need for gas tightness and enhanced torque capabilities. Last but not least, it was discovered that, among all oilfield equipment used during upstream operations, it was (next to advancements inSSSV's)the constant evolution of tubular connectiontechnologieswhat contributed to "crystallize" the modern concept of Well Integrity, especially after the big offshoredevelopments seen from 1971 on. As a corollary, the impact of current standardization protocols ISO 13679 / API 5C5 on well integrity in terms of metallic seal integrity will be assessed in the light of the tribological and mechanical evolution of the MTM seal during testing and validation.
Analysis and Optimization of Bubbly Oil Production in Heavy Oil Reservoirs
Authors: Temizel Cenk , Moreno Raul , Jia Bao , Alkouh Ahmad , Al-Otaibi Basel , Kyanpour Mohammad
Published: October 2017

Some heavy oils reservoirs present an unusual behavior when put on production under significant drawdown conditions. In these reservoirs, the high formation depressurization increments the recovery factor and accelerates the production rates driven by a solution gas mechanism. Due to the chemical and physical properties of these oils they tend to stabilize the dispersion of gas bubbles, promoting the generation of foam in the oleic phase. This foamy oil when compared with conventional oils result in a more productive response at similar drawdown conditions. The foamy oil phase behavior is the result of a number of complex mechanisms and requires a good understanding on each of them to estimate the potential response of these reservoirs. In this work, the role of key factors that affect the bubbly oil production is summarized.

To outline the significance of key variables on the performance, a commercial optimization and uncertainty analysis software coupled with a mechanistic simulator is used. The simulator allows a detailed modeling of the physics involved on the generation and behavior of the foamy oils, in which the foamy oil is modeled as a disperse phase of gas bubbles in the oleic phase, including small mobile gas bubbles and larger trapped gas bubbles flowing as discontinuous gas dispersion which affect foam viscosity, compressibility, mobility and relative permeability. Fluid properties used in this work are from Maini (1996).

The sensitivity and optimization analysis performed in this work on key reservoir variables and well operational parameters shows the significance of each factor on the production response. The relative importance of each variable is reported in tornado diagrams. Results showed that a strong approach on handling the reservoir unknowns are as crucial as the control of operational parameters from reservoir management point of view.

Nowadays the foamy oil behavior and its favorable production response are not totally well understood. Solutions have been proposed but they are still controversial and the use of horizontal wells introduces more complexity in the production operations. In this work is provided an in-depth optimization and uncertainty analysis to outline the role of each major parameter affecting the production response and the recovery efficiency in this type of reservoirs using horizontal wells.
Uncertainty Analysis and Design Optimization of Gas-Condensate Fields
Authors: Abdul-Latif Benson Lamidi , Fathi Elsharkawi Ahmed Mohammed , Daniel Edem Tsikplornu
Published: October 2017

Unlike conventional reservoir development, uncertainty analysis and design optimization of unconventional reservoirs have caught less attention because of a general notion that oil field production data analysis and computational methodologies and techniques can be applicable to unconventional reservoir developments. In order to predict production profiles in unconventional reservoirs, it is essential to understand the uncertainties and performance of unconventional reservoirs. In this paper, the most relevant factors influencing the production of gas-condensate in a domain of real data from gas condensate fields is investigated and reviewed.

To identify the major factors affecting the production of condensates from heterogeneous and ultra-low permeability reservoirs, third and fourth order factorial design (Box Behnken technique) were used on a domain of gas-condensate field data to perform the uncertainty analysis. A semi-analytical surrogate model for Monte Carlo analysis was also proposed in this paper.

Condensate blockage radius, reservoir permeability, well spacing, reservoir thickness; compressibility, initial pressure; fracture spacing and initial condensate saturation were noted to be the most substantial parameters influencing condensate production. Validation of the results proved that the proposed surrogate models for gas-condensate reservoirs could reliably be used to forecast condensate values in heterogeneous and ultra-low permeability reservoirs.

This paper also presents a semi-analytical model applicable to unconventional reservoirs to incorporate the effect of condensate banking in the design optimization of hydraulic fracturing. Analytical models for Darcy flow above and below the dew point pressures were considered whilst estimating the optimum fracture design in gas condensate reservoirs using Schechter's approach incorporating the effects of the condensate blockage radius.
A New Method of Backup Cutter Layout to Extend Bit Life Without Sacrificing Rate of Penetration
Authors: Chen Shilin , Khlefat Yazan , Cleboski Chris , Anderle Seth , Maouche Zakaria
Published: October 2017

This paper discusses a new and general method of backup cutter layout to extend bit life without sacrificing rate of penetration and two field case studies. This method includes the following aspects: Ensuring backup cutters do not cut or only partially cut when their primary cutters experience little to no wear and when the depth of cut of the bit does not exceed an expected value. This aspect is enabled by allowing backup cutters to have a minimal critical depth of cut that is greater than the depth of cut of the primary cutters.Ensuring backup cutters act as major cutters when the primary cutters' wear depth is equal to or greater than the underexposure of the backup cutters. This aspect is enabled by allowing each backup cutter be rotationally behind its primary cutter by approximately 180° or greater. The underexposure of each backup cutter relative to its primary cutter is carefully calculated based on the primary cutter's wear and drilling slope.
Real-Time Integration of Geo-Mechanics to Overcome Drilling Challenges and Low NPT
Authors: Al-Zankawi Omran , Belhouchet Mohamed , Abdessalem Abba
Published: October 2017

Most drilling-related incidents are caused by unstable boreholes, whether they are caused by lost circulation, packoff, or stuck BHA and/or casing. One of the main objectives of this study was reduction in drilling incidents and associated Non Productive time (NPT) while drilling wells in a particular area of Kuwait, where often extremely challenging environments were faced due to wellbore instability arising from tectonic stresses, associated faults, fractures, complex structures, and anomalous pore pressure. Additional challenges were presented by a complicated and highly deviated well design, where planes of weakness of the formation being drilled and their relative angle with respect to the well path become crucial factors in assessing stability of the borehole. Multiple failure mechanisms such as stress induced wellbore instability, invasion of drilling fluids into weak bedding / micro-fractures and osmotic sensitivity, were found to be the root cause of wellbore instability across reactive shale formations especially during drilling of highly deviated wells.

In lie of these challenges, a comprehensive study was conducted to overcome the wellbore stability issues and investigate feasibility of drilling Ahmadi wells of Kuwait at high deviation. Correct mud weight (MW) prediction was one key factor during the drilling stage to keep the wellbore stable and deliver good borehole geometry (Figure 1). The key objectives of the study were to define a safe MW program for the vertical and deviated sections of the planned well by conducting a wellbore stability study and to determine a real-time strategy to mitigate and-or manage wellbore instabiity problems as they arise.

The scope of work included root cause analysis of drilling events, development of mechanical earth models (MEM) for offset wells, integrating sections of the MEM from the offsets to the planned well trajectory, and a safe MW program for planned well.

The paper describes the process of optimizing the drilling practices based on geomechanical outputs, to overcome serious drilling hazards and application of real time geomechanical monitoring for successful drilling. This application promises to open the prospect of drilling similar wells without complications and reduce NPT in Kuwait.
Development and Field Trial of New Acid Soluble Drilling Fluids
Authors: Wagle Vikrant , Al-Yami Abdullah S. , Al-Bahrani Hussain , Awadh Abdulla
Published: October 2017

Stuck pipe, historically, has presented huge challenges to the worldwide oil industry. Stuck pipe has resulted in a great amount of nonproductive time, thereby causing huge monetary losses to the oil industry. A new drilling fluid has been designed, which employs a combination of two different weighting agents viz. barite and manganese tetroxide (Mn3O4) to overcome the problems linked with stuck pipe. Drilling fluids formulated with a combination of manganese tetroxide and barite as weighting agents are expected to have the following advantages: a) Better sag resistance, b) lower equivalent circulating density (ECD), c) lower fluid cost, and d) stuck pipe mitigation due to acid solubility of manganese tetroxide.

This paper describes the formulation of 100 pcf and 150 pcf drilling fluids formulated with a combination of barite and Mn3O4 as weighting materials and hot rolled at 270°F and 300°F, respectively. The experimental work involves measuring rheological properties and high temperature, high pressure (HTHP) fluid loss at the specified temperature. Barite sag measurements were also performed on 150 pcf drilling fluids to determine the sag resistance of the fluid. The paper describes results of using different organic acid based filter-cake breaker fluids for the partial dissolution of Mn3O4 based filter cake. The paper also describes the data obtained from the field trial of 100 pcf and 155 pcf fluids formulated with barite and Mn3O4 for wells with a BHST of 290°F.

The paper discusses the advantage of using such drilling fluids in mitigating stuck pipe issues and highlights their benefits in terms of better barite sag resistance and lower equivalent circulating density as compared to conventional drilling fluids formulated with barite as weighting agent. The 100 pcf and 150 pcf fluids showed superior rheology, thin filter cake and better sag resistance as compared to fluids formulated with only barite as the weighting agent. Different organic acids were able to partially dissolve the filter cake of drilling fluids formulated with barite and manganese tetroxide as weighting agents. This partial dissolution of filter cake is sufficient to free the pipe in the case of any stuck pipe event in the wellbore. The drilling fluids formulated with a combination of barite and manganese tetroxide showed good rheology, barite-sag resistance and resulted in successful drilling of wells having a BHST of 290°F.
Thermo-Mechanical Properties of Annular Sealants—A Path to Optimized Wellbore Integrity and Economics
Authors: Jimenez Walmy Cuello , Pang Xueyu , Urdaneta Javier A. , Sørensen Espen , Lende Gunnar , Nimane Sudhir
Published: October 2017

Understanding the heat transfer phenomena encountered in extreme oil and gas reservoir environments [i.e., thermal recovery, high-pressure/high-temperature (HP/HT), deepwater, etc.] and geothermal wells is important to enhance the exploration and production of subterranean energy resources. However, there can be a lack of information about thermal properties of current oilwell cement systems, which are key inputs for any cement sheath stress simulator that accounts for the thermal cycling effect on the integrity of the annular sealant. Having thermal data for multiple sealant systems is important to allow for risk reduction and production maximization by reducing wellbore construction uncertainty during the planning stage, therefore allowing operators to make well-informed decisions.

This paper discusses the thermal conductivity and thermal expansion of neat, foamed, and elastic oilwell cements. These properties were measured in hydrated and dehydrated states at ambient pressure and at temperatures ranging from 25 to 100°C (77 to 212°F). Both thermal conductivity and thermal expansion measured on dehydrated cement samples were less than hydrated samples, which is most likely attributed to the effect of evaporable water within the cement specimens. Mathematical relationships were derived for thermal and physical (i.e., density) properties of cement, thus allowing for approximate characterization of the thermal behavior of oilwell cements. The effect of the thermal properties of different cement systems on the integrity of a typical thermal recovery well was evaluated as a case study. Elastic properties of the aforementioned cement systems were also studied, yielding characteristic curves for each system. Moreover, the impact of cyclic loads on determining acceptable stress levels of annular sealants is also presented, along with its economic benefits. This allows for the optimal design of dependable sealants for long-term integrity during the planning stage.
How to Use Drill String Vibration Data to Reveal Geology Phenomena in Geosteering Jobs: An Application Sensor at the Bit
Authors: Sitinjak Eri Sarmantua , Kurniawan Baladika , Besol Yusuf
Published: October 2017

Drillstring vibration information can be used to define the geology of the well. Some geological phenomena in horizontal wells can be revealed from drill string vibration data. Examples include faults, exiting and entering the reservoir, different lithology and rock strength. In addition, uncontrolled vibrations can also limit the optimization of drilling performance, for instance increasing the possibility of stuck pipe, affecting wellbore stability, reducing drilling tool life, and causing tool failure. This paper aims to gather vibration data from drilled horizontal wells and classify them based on the geological and lithological environment in which they were observed. Three major kinds of vibrations are resulted from horizontal drilling; axial vibration, lateral vibration, and torsional vibration. Vibration data were collected and grouped together to correlate vibration behavior to the geology of the horizontal well. These vibrations data were compared in different geological situations; for example in clastic and carbonate environments, drilling through changing lithology, exiting the reservoir, and passing through a series of faults. The correlation can then be utilized in geo-steering application.

The objective of this paper is to enable engineers to characterize the vibration data according to potential risk factors that may be encountered during real-time geo-steering, and to take actions that optimize the drilling operation. Observations have revealed a strong correlation between vibration behavior and geological phenomena in drilling operations. These observations enable confirmation of various geological features from geo-steering modelling. Furthermore, adjusting drilling parameters and implementing good drilling practice would minimizes the tool exposure to excessive vibrations in order to avoid tool failure, and optimizes drilling operation. An understanding of the vibration data can also be used to help geo-steer and support the justification for any adjustment in the lateral section. This will not be a proactive adjustment but more of a reactive adjustment. An additional objective is to find the best tool configuration in certain horizontal well environments, thereby improving the drilling optimization and enabling optimum procedures by capturing the right downhole dynamics when encountering excessive vibrations. These findings will help drilling to control the well and contribute to the wellbore stability. This will be the first paper to characterize vibration behavior in relation to the geological phenomena and applying it in horizontal wells.
Water Control Management Utilizing Downhole Water Sink Technology: Application of a Reservoir in the Middle East
Authors: Al-Azmi Nasser H. , Aladwani Faisal A. , Kasaraneni Pruthvi R.
Published: October 2017

Produced Water is a major challenge in the oil and gas industry. Water production increases worldwide as more reservoirs depleted over time thus more resources needed to handle the unwanted produced water. Managing the subsurface water conformance maximizes hydrocarbon production and reduces operating cost that is mainly expected from the unwanted water production. It is important to identify the water source to solve any problem related to the unwanted excessive water production. Once the mechanism of the water production is understood, an effective strategy can be designed to detect and control the produced water. Different technologies and methods have been developed to control produced water. For example, Production Logging Tool (PLT) and Chan's WOR diagnostic plot are two common methods for determining the presence and causes of the unwanted excessive water production. In this study, Downhole Water Sink (DWS) completion technology is adapted to maximize reservoir recovery by reducing water cut with oil production, the excessive water is produced through a bottom completion and the oil is produced from the top completion. The design of a successful DWS requires detailed planning for the completion location and the production strategy. The aim of this study is to evaluate DWS technology performance in vertical oil wells located in Middle East Reservoir, which have severe water coning. In addition, economic analysis results were obtained by comparing the conventional wells with DWS wells to investigate the effect of DWS in reducing the operating cost. Results showed that the DWS completion minimized the water production by 18% and enhanced oil production by 26% compared to the conventional completions. In addition, several diagnostic tools applied to evaluate the water to enhance the proposed solution in which is applied to the candidate reservoir.
Making Water Injection Interventions Work: The Importance of Understanding Thermal Effects in Fractured Water Injectors
Authors: Duvivier G.. , Al-Naqi M.. , Ameen A. A. , Al-Enizi N.. , Al-Shati A.. , Rajan S.. , Clark R. A.
Published: October 2017

Stimulating water injectors successfully is critical to any waterflood and to successfully stimulate wells it is important to understand what technology works and what does not. An effective method of evaluating stimulation efficency is by monitoring the long term performance of the water injectors and how injection pressure and temperature varies over time.

The primary source of injection water for Greater Burgan is produced water, which is collected through an extensive gathering system. Because this gathering system is so large, the resulting fluids drop to atmospheric temperature before they are available for injection. Average daily temperatures in Kuwait vary by more than 60°F annually. All of the injection wells are injecting above fracturing pressures and these temperature swings impact the size of fractures leading to observed changes in rate of up to 40%. These effects must be understood to evaluate the impact of injection fluid temperature upon stimulation.

Monitoring this surface injection data has allowed the team to select a successful stimulation method for the injectors and added significantly to the field's injection rate.