bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Evaluation of Viscoelastic Surfactant Acid Diversion for Carbonate Reservoirs: Parameters and Performance Analysis
Authors: Al-Otaibi Msalli A. , Al-Muntasheri Ghaithan A. , Hussein Ibnelwaleed A. , Chang Frank F. 
Published: September 2011

Abstract
Formation damage minimization and removal are essential to field productivity enhancement and production target achievement. While formation damage is anticipated during drilling, an effective treatment fluid becomes important to bypass mud damage and enhance well productivity. Most of the fluids used in acid stimulation of carbonate wells are consumed in the high permeable zones – leaving the low permeability and damaged zones not effectively stimulated.
Viscoelastic surfactants (VES) have been introduced in the industry to overcome this challenge and offer effective uniform treatment over long horizontal well intervals to treat damaged and low permeability zones. The viscoelastic surfactant molecules form rod-like micelles in the presence of salt at specific pH condition, which results in significant viscosity increase. Therefore, when added to acid systems, the VES helps in increasing the viscosity of the solution based on the state of the acid-carbonate rock reaction. Customizing the treatment to the field's needs is a key factor to the success of the stimulation treatment. The treatment design includes the carrying fluid type and VES concentration. These parameters need to be optimized to achieve a uniform distribution of the treatment and effective acid diversion.
This paper studies the diversion ability of VES acid system in comparison to straight acid systems. Also, it evaluates the impact of permeability, salinity, and VES concentration on the diversion efficiency of the VES acid system. For the first time in the industry, the diversion efficiency was shown through return permeability results to be heavily dependent on salinity of the mixing water, VES concentration, and permeability contrast. Increasing the salinity and VES concentration enhanced the diversion efficiency significantly, while increasing the permeability contrast reduced the diversion efficiency.
Core flooding equipment capable of flowing two parallel core samples was used to study the VES acid system diversion efficiency at various permeability contrasts. Carbonate core samples with permeabilities in the range of 0.7-56.25 mD were used in the study. The VES acid system carrying fluid salinity effect was investigated by comparing the diversion obtained by distilled water, field water and seawater at different VES concentrations. Two VES concentrations were used to evaluate its impact on diversion, 3.75% and 7.5%. These parameters were studied at 1,000 psi for pore pressure, 2,000 psi for confining pressure, and 150 °F for temperature.
The Role of Geomechanics in Diagnosing Drilling Hazards and Providing Solutions to the Northern Iraq Fields
Authors: Abalioglu I. , Legarre H. , Garland C. , Sallier B. , Gao J. , van Galen M. , Chou Q. , Neil B. , Soroush H. , Qutob H. , Mahli Z. 
Published: September 2011

Abstract
The integrity of the wellbore plays an important role in petroleum operations (e.g., drilling, completion, production). 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 (i.e., selecting optimal trajectory and bottom-hole pressure) 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 (e.g., hole washout, stuck pipe, extra cuttings/cavings, tight holes). 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 Chemistry for Drilling Fluid Additives
Authors: Zheng Jun , Wang Jianzhao , Musa Osama M. , Farrar David , Cockcroft Bob , Robinson Alison , Gibbison Robert 
Published: September 2011

Abstract
The enhanced performance of drilling fluids, especially High-Temperature, High-Pressure (HTHP) compatibility, will allow faster and safer drilling in challenging environments. This paper presents a novel class of synthetic polymers that were developed as high performance rheology modifiers (viscosifiers). The leading polymer candidate was shown to be an effective thickener, with excellent salt-tolerance and thermal stability compared to conventional viscosifiers used in water-based drilling fluids.
This new class of synthetic polymers was suitable for demanding drilling conditions where conventional viscosifiers cannot perform satisfactorily. For example, xanthan gum is known to start losing rheological properties above 250-300°F so it is not always suitable for HTHP drilling operations. A desired rheology modifier should possess similar rheological properties to xanthan gum (e.g. highly shear thinning) with enhanced salt tolerance and thermal stability. These enhanced properties will allow drilling fluids to maintain critical functions under harsher field conditions.
This paper presents the basic characteristics of the newly developed polymeric rheology modifier as well as its rheological and thermal stability properties. The rheological properties of the polymers were studied in fresh water, in brines and in formulated drilling fluids. Thermal stability studies were conducted using stainless steel pressure aging cells, a roller oven, and a conventional oven. The novel polymer developed was shown to exhibit a similar thickening efficiency and rheological profile (i.e. shear thinning) to xanthan gum. After thermal aging up to 350–375°F (177–190°C) for 16 hours, drilling fluids based on this polymer were shown to maintain excellent rheology and suspension power. The new synthetic rheology modifier also demonstrated synergistic effects with other ingredients commonly used in water-based drilling fluids, further enhancing thermal stability.
Development of these high-performance drilling fluid additives is critically important to the drilling industry. HTHP compatible drilling fluids may allow more environmentally-friendly drilling operations to be undertaken in a safe and efficient manner.
Universal Technique Normalizes and Plans Various Well-Paths for Directional Drilling
Authors: Liu Xiushan 
Published: September 2011

Abstract
Appropriate well-path planning is the prerequisite for operators to drill directional and horizontal wells successfully. Since the goal of drilling is to tap the oil from the complex reservoirs, and the well-path design requirements, subsequently, are different. Operators generally plan a directional or horizontal well in a 2D plane if no special requirements are imposed, and mostly consider the build and drop well sections as circular arcs. It seems very easy to plan such a simple profile, but conventional techniques are so inconvenient for use, as highlighted in the following situations:
Conventional methods require different formulas for planning different well profiles. Thus, the variety of well profiles leads to the variety of design formulas and methods. Conventional methods only consider the section length and inclination angle of a hold section as unknown parameters while planning a well profile. It means that other parameters of the well profile are given as known parameters and can not be directly designed to meet the specific requirements. Conventional methods only provide one set of formulas for a well profile and often require trial-and-error procedures to get the reasonable results. Well planners have to make tentative calculations again and again, and hardly exclude the interference of subjective factor.
This article provides a universal method of normalizing and planning various well profiles, which includes two core technologies. First, the author constructs a general-purpose well profile that covers all of arc-type profiles those consist of circular-arc and straight-line sections with any combination. Secondly, the author presents the constraint equations and all of possible analytical solutions, which yields a new technique of planning a well profile that any two characteristic parameters can be arbitrarily selected as unknowns.
The universal solution presented for planning various well profiles achieves the mutual validation and optimization of characteristic parameters among one another, and solves the problems on the variety and optimization of well profile design. The methods proposed represent significant improvements over the conventional well-path planning techniques, were programmed into computer software, and have proven satisfactory for several hundreds of directional and horizontal wells.
Effect of Drill Solids on the Prediction Accuracy of a Viscosity Model
Authors: Misra Garima , Jamison Dale E. , Whitfill Donald L. 
Published: September 2011

Abstract
Lost circulation is one of the most troublesome and expensive problems encountered in drilling. Software with specialized modules may reduce the number of lost circulation incidents by improving understanding and planning. Hydraulic modeling and design software can predict the equivalent circulating density (ECD) throughout an interval. By selecting another module, the user can calculate the fracture width that may be initiated and optimize the material and particle size distribution to help achieve effective propping and plugging of the fracture. Rheology changes resulting from the addition of specialized lost circulation material (LCM) can be determined with another module, and this information is then cycled back to update ECD calculations.
The viscosity module predicts the LCM-laden fluid viscosity for both non-aqueous and non-dispersed aqueous fluids quite well. Additional laboratory experiments have validated the current module for other parameters, such as prediction accuracy with drill solids present in both water- and oil-based systems. A wider range of mud weights was also evaluated. The data shows that the presence of three different types of drill solids, even in substantial amounts, does not affect the prediction accuracy of the current viscosity module. The ECD calculations performed on both measured and predicted rheologies resulted in percent errors in the range of 0.06 to 4%, which is acceptable for hydraulics analysis and indicates the accuracy limit.
Enhancement of Oil Recovery through "Dump-flood" Water Injection Concept in Satellite Field
Authors: Shizawi Wafa , Subhi Hamed , Rashidi Ahmed , Dey Arunangshu , Salmi Fathiya , Aisary Mohammed 
Published: September 2011

Abstract
W-field is a small satellite field that started seeing some means of pressure depletion. Field development study recommended waterflood as the most effective option to arrest the reservoir pressure decline and enhance the oil production and recovery.
The size and the satellite location of the field could not economically justify a conventional water flood project. A "DumpFlood" concept was implemented where a single well is used as a source of water supply and inject domain. The well was perforated in the deeper water reservoir Z and on the injection target reservoir H. The well was completed by an advanced ESP that was designed to produce and inject in the same wellbore across the two set of perforations.
Surveillance program was put in place and implemented focusing on reservoir pressure monitoring in the surrounding wells, production metering and periodical surface flow of the dump flood to assess its productivity and injectivity. Downhole gauges were installed in the dumpflood well across the two units to monitor the reservoir pressure behaviour and the calibration of the injection rate.
The concept proved its success, an injection water rate of around 1200bpd was achieved in the target zone. Pressure response and some segneficant oil gain in the range of 40% was noticed in the w-feild. The concept is now under review for further implementations in the same field and the design is ongoing to apply the concept in other two fields in the area.
The dumpflood concept allowed an economical waterflood project to be applied in Z fields with the expectation of significant oil recovery to be achieved.
Enhanced Sustained Production from Successful Underbalanced Coiled Tubing Drilling in Saudi Arabian Deep Tight Gas Sandstone and Carbonate Formations
Authors: Al-Omair Ahmed , Al-Jamaan Hamza , Rahim Zillur , Al-Malki Bandar , Al-Kanaan Adnan 
Published: September 2011

Abstract
Gas encountered in deep carbonate (Khuff) and deep sandstone (Jauf and Unayzah) formations require significant planning and impelemntation of high-end technology for optimized exploitation. The conventional drilling methods for vertical, horizontal, and maximum reservoir contact (MRC) have been used extensively to produce the reserves. The need to avoid formation damage and minimize differential sticking has become important to maintain the well integrity and rates, particularly in reservoirs that are tight and encountering pressure depletion with time.
Underbalanced Coiled Tubing Drilling (UBCTD) technology is a breakthrough in developing mature and depleted reservoirs. With UBCTD, workover operations, such as drilling laterals in very thin reservoir sections and controlling their trajectories with flexibility to steer into net pay sections, are achieved with more accuracy. Also, the high operational costs with rig time, the need of inducing hydraulic fractures and drill-in mud invasion caused by conventional drilling are avoided. In addition, the technology plays a major role in eliminating pressure differential sticking while drilling across multilayered reservoirs that exhibit layering depletion. The technology was introduced after conducting a pilot project with six wells where post-UBCTD production performance were analyzed and exceeded expectations. In some cases, UBCTD provided as much as a threefold increase in initial well productivity and achieved a higher, long-term sustained rate compared to conventional workover operations conducted in similar reservoirs. Due to the ability to continuously monitor well performance during drilling and the higher flexibility of coiled tubing (CT) operations, changes in drilling direction and inclination could be easily made to maintain the drill bit in layers of interest and enhancing reservoir contact in the desired sections.
This paper presents two actual examples from carbonate and sandstone reservoirs where UBCTD has been successfully deployed. The post-workover pressure and production performances and comparison with results obtained from conventional drilling are presented to illustrate the improvement in gas rate. The paper also presents pressure transient tests conducted after workover operations indicating low or zero skin damage and high permeability-thickness (kh) as a result of effective minimization of wellbore damage from drill-in mud and achieving higher net-pay contact.
Geosteering Improvement With A Telemetry Model
Authors: Hartmann Andreas , Akimov Oleg , Fulda Christian , Morris Stephen 
Published: September 2011

Abstract
Introduction of new measurements constantly increases the amount of real-time data from logging-while-drilling (LWD) services. This is matched by telemetry technologies that provide data rates from bits to Mbits per seconds. During a deployment, the bandwidth is shared between several services requiring different data rates, leaving the user with the task to align telemetry technology and shared data rates to the application. High-volume services often allow for data compression. Lossless or near lossless compression provides best data quality but makes a service greedy for bandwidth. Lossy compression drastically reduces bandwidth usage, but may result in degraded data quality. Thus, planning the telemetry must be closely tied to the service objectives and expert advice is required.
We present a planning approach where we model the real-time data compression of an LWD high-resolution imaging tool that uses a flexible compression algorithm. This system allows lossy compression for telemetry rates as low as 1 bit/s, while at the same time can deliver memory data quality using high-speed telemetry technology. The compression rate determines the image resolution and must be adjusted to the detail required in the transmitted image. Using offset well data or simulated memory data, the expected real-time image is simulated and its level of detail quantified. For instance, the presence and appearance of fractures in real time can be forecasted. This enables us to optimize telemetry usage and define compression and drilling parameters for a successful deployment of the imaging service.
The paper will outline the methods and benchmark the technology using real-time data measured during field deployments. We will then use parameter variations to show how increasing net bandwidth improves the amount of detail in the images and how these are used for different levels of real-time data interpretation.
Cementing at High Pressure Zones in KSA "Discovering Mystery behind Pipe"
Authors: Al-Dossary Abdulla Faleh , Al-Majed Abdulaziz , Hossain M. Enamul , Rahman Muhammad Kalimur , Jennings Scott , Bargawi Riyadh 
Published: September 2011

Abstract
Cementing is one of the most important and crucial issues in the oil field, especially for high pressure and gas bearing formations. It is difficult to achieve a good zonal isolation in such formation types, where pressure is abnormal and formation fluid contains corrosive fluids and gases. A common problem associated with highly over-pressurized zones is cross-flow after cementing. Fluid flow from an over-pressured zone to a low-pressure, high-permeability zone can lead to deterioration of the existing production hardware. Work over operations that attempt to repair cement voids — including: perforation, squeezing and use of casing patches or scab liners — are not recommended, as they do not provide long-lasting results. In one onshore field in Saudi Arabia, there was a problem related to cementing at high pressure zones. Recently, communication between A (abnormally over-pressurized zone) and B (low-pressure zone) formations occurred due to long term sea water injection, and has resulted in production interruption in a few wells. This paper addresses the problem through investigating field practices, including: drilling, cementing, and completion. This study also reviews the field reports and cased hole logs. A three-month study was conducted to evaluate the effects of formation-A water on cement, where the cement was exposed to formation-A water under downhole conditions. The tests for permeability, mechanical properties TGA and EDXRF are presented, in addition to discussions of some of the preliminary findings.
Shallowest Horizontal Well Drilled in the Middle East: Challenges and Successes
Authors: Dutta Abhijit , Al Azmi Bader M. , Al Abri Hakim , Ali Musab 
Published: September 2011

Abstract
Major plans are underway to exploit the vast resources of heavy oil in very shallow regions of Kuwait. The horizontal well, an important tool for commercial exploitation, poses great challenges in shallow depths and requires high dogleg severity (DLS) through extremely loose formations while drilling with a conventional Kelly drive rig. This paper highlights the challenges encountered and the use of multi-tier planning and perfect execution that enabled the successful drilling and completion of the shallowest horizontal well ever drilled in Kuwait and the Middle East region in the first attempt. Two medium-radius, extremely shallow horizontal wells were successfully drilled using a conventional Kelly drive rig. The success of both wells introduces the application of horizontal well drilling in heavy oil reservoirs, which is expected to maximize production per well and reduce the large number of vertical wells planned, thereby reducing costs of the project.
Concerns were raised regarding the feasibility of drilling such a well with high DLS through grossly unconsolidated sands with a conventional rig to successfully lower all the casings. Meticulous planning, engineering analysis, proper tool selection, and development of drilling procedures were performed before undertaking the venture. The experience of drilling 75 similar vertical wells was extremely valuable while planning and completing the project.
Kuwait Oil Company (KOC) approached the project in a holistic manner. The drilling group prepared several plans and deliberated at length with asset and service partners to analyze and firm up the plan. The advantages and disadvantages of a conventional rig versus a slant rig or top drive rig were also analyzed. KOC ultimately used the cost-effective conventional rotary rig and were able to successfully drill both wells. The first well reached horizontal at a shallow TVD of 680 ft with a kick-off point at 96 ft and a 1,290-ft lateral completed with a liner through unconsolidated loose sand.