bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integration of Conventional Logs, Core, Borehole Images, and 3D Seismic, A Rule of Geological Modeling in Tight Clastics Gas Deep Reservoirs, Oman
Authors: Farag Ashraf , Al Hasani Hanaa , Al Lawatia Redha H. 
Published: January 2010

AbstractIntegration of conventional logs, core and 3-D seismic with borehole images provide a reliable and decent approach to geological modeling in tight clastics deep gas reservoirs in Oman. The Studied field is of Cambrian-Ordovician age. The field structure is North-South elongated domal anticline associated with a salt pillow.The main hydrocarbon bearing and producing reservoirs are predominantly of continental to marine environments in the deepest part: aeolian dominated formation (A) to sabkha dominated formation (B) in middle intervals and non-marine (coastal plain) to shallow marine (intertidal-subtidal) (C) sandstone members at the shallowest levels.The seismic image quality at the reservoir levels are poor, mainly due to the weak acoustic impedance contrast between deep reservoirs and the overlaying shale, besides the presence of multiple noises further obscured the event, in addition to limited number of core intervals all over the field.In order to refine the structural, depositional model and facies distribution for clastic tight gas deep reservoirs, a detailed integrated borehole resistivity images log interpretation with the available data was performed. Structural dip, structural features like faults locations and their strike and dip angles, sub seismic faults for field transmissibility, and compartments, natural fractures, sedimentological and facies analysis where core - logs comparison was done to improve the rock typing which later correlated to the petrophysical properties, are the major achievements from this study. The study has also analyzed the major accumulations and the paleo-current and paleo wind directions over the reservoirs units by predicting their paleo-drainage and sediments entry points. These results formed valuable input to the field geological modeling.The exercise of tying the above results with seismic data was carried out with a very effective methodology for the generation and significant improvement of a new geological model to support further development and added new reserves in tight gas reservoirs.
Estimation of Production Potential and Reserves of Jauf Gas Reservoir of Bahrain Field
Authors: Al Owainati Ebrahim , Al Muftah Ali , Kumar K.. , Murty C.R.K.. R.K. 
Published: January 2010

Abstract
In recent years Bahrain has experienced a rapid growth in gas demand for industrial use, electricity generation, gas injection, and artificial lift. The main source of gas for these needs is the Khuff reservoir only. This recognition of this fact has been the main driver for the exploration of the deep gas prospects in Bahrain field.
Jauf formation has been found to have hydrocarbon potential regionally. It has been found hydrocarbon bearing in the flanks of Ghawar anticline. Jauf sandstone has also been found to be highly prospective exploration target in the Bahrain field, since it has been proved gas bearing in the crestal well. The well flowed with moderate gas rates before sanding up.
In addition to the crestal well, five other wells penetrated Jauf zone. Three wells gave clear gas shows and two peripheral wells tested water. Long testing was done in one of the three wells to produce gas from Jauf. This well produced from Jauf for more than two years before Jauf was plugged and more prolific layers were opened in the well. Jauf produced at an average rate of 15 MMSCFD.
In order to estimate the gas reserves and the production potential in Jauf, uncertainties with gas reserves estimate and the reservoir continuity should be considered. Rock properties, drive mechanism, fluid properties, pressure, gas quality, and the production tests play vital role in estimating the reserves. Therefore, two approaches were used to estimate the Jauf gas reserves: around gas tested well-bores and as a continuous medium. The paper will describe each approach and further will present the results.
As there are good reasons for the Jauf reservoir to be continuous within the Bahrain field area, a simulation model was built considering the data from all the drilled wells using only the lower limits for all the reservoir parameters like porosity, net thickness, and saturation. Performance forecast was also carried out to evaluate the sustainability of the plateau gas rates, which will be discussed in this paper.
Cement Considerations for Tight-gas Completions
Authors: Darbe Robert , Ravi Kris 
Published: January 2010

Abstract
Recent advancements in completion technology have made tight-gas bearing formations more attractive for production. However, long horizontal sections with multiple fracture treatments can influence the effectiveness of the seal provided by the cemented annulus which, in turn, can affect the productivity of the completed well. Therefore, planning for cementing, followed with proper design and execution, is important to overcome the challenges associated with tight-gas well completions and production.
It is challenging to centralize casing strings placed in highly deviated wellbore sections. Poor centralization results in a non-uniform annular-flow profile as fluids tend to flow along the path of least resistance. If this phenomenon exists during cement-slurry placement, an uncemented channel can result on the narrow side of the annulus creating a flow path for fluids to migrate within the annulus.
Effective cement slurry placement resulting in an initial annular seal does not guarantee that the seal will be maintained through subsequent completion events. A cement sheath is, by nature, brittle when it is exposed to the stress environment that high pressure hydraulic stimulation produces. The cement sheath can crack, resulting in unwanted flow paths. In addition, fracture attempts early in the completion of a tight-gas well can weaken the hardened cement through fatigue, breaking the cements' sealing capability.
The lack of a cemented annular seal can result in the inability to control wellbore fluids affecting both the fracture treatments and subsequent production. If the cement sheath allows fracturing fluids an alternative path, then fracture initiation points might not occur at the desired location, minimizing the stimulation effectiveness. Production gases can also follow an alternative path, which allows for uncontrolled flow to thief zones and to the surface.
This paper discusses cement-slurry placement and enhanced sealing properties that a cement system should possess to help withstand the tight-gas completions.
Overcoming the Cementing Challenges in Deep Gas Environment
Authors: Ravi Kris , Darbe Robert 
Published: January 2010

Abstract
Developing and producing a deep gas asset is a challenge because the reservoir is often of low permeability, commonly referred to as tight gas. In some cases, the wells are drilled under-balanced to prevent damaging the reservoir. Very often, it is necessary to drill through weak, depleted zones to reach the reservoir. These factors pose unique challenges to cementing materials used and methods applied. These challenges need to be understood in detail and solutions designed and implemented successfully for economical production of gas from deep environment.
Properties of cementing fluids, spacer and cement-slurry, should be optimized to enable successful cementing when the well is drilled under-balanced. The importance of properties such as fluid loss, density, and resistance to formation fluid influx are discussed and presented. Spacer fluids and cement-slurry need to be optimized based on reservoir parameters to help prevent fluid influx from the formation. The rate at which the slurry develops static gel strength is an important parameter to help prevent formation fluid such as gas from entering the annulus and either flow to other zones or come to the surface.
When drilling through depleted, weak zones the circulating and hydrostatic pressure should be minimized to help prevent losses to the formation. The density and rheology of the cementing fluids influence these values and should be optimized to help ensure successful placement of cement-slurry when there is a risk of losses. Design of the spacer fluid and cement-slurry to help prevent losses are discussed and presented. There are distinct advantages of using different chemical treatments ahead of the cement-slurry to control the losses. Different chemical treatment options will be presented and discussed.
The solutions discussed in this paper should help in constructing and operating the deep gas wells economically and safely.
Development and Optimization of 12-in. PDC Bit for Powered Rotary Steerable Systems in Deep Gas Drilling in Saudi Arabia
Authors: Reda Saeed Al , Kubaisi Abdullah , Nawaz Khalid , Jamil Muhammed Fouad , Alvarez Octavio , Qattawi Baseem , Verma Jaywant , Ganda Sukesh 
Published: January 2010

Abstract
Directional drilling the 12-in. curve section in the deep gas fields in Saudi Arabia is very challenging because of the hard formations and harsh drilling conditions. The section consists primarily of hard limestone and dolomites interbedded with anhydrite. The main challenges of drilling this section include multiple bit trips and reduced rates of penetration (ROP).
To overcome these challenges, the operator, directional drilling service company, and drill bit company in collaboration developed an optimization process to create and evolve a polycrystalline diamond compact (PDC) bit design to be used on powered rotary steerable systems (PRSS).
The objective of the optimization process was to increase the ROP and the durability of existing PDC bits to eventually lead to drilling longer intervals by minimizing the number of bit trips while drilling with PRSS. The challenge required the development of a new PDC technology in conjunction with optimized drilling practices and a reliable drive system.
The challenges were overcome by implementing the specific bit design algorithms incorporated with new cutter technology, and using drilling simulation software to optimize the bit cutting structure design in directional drilling environment. Significant improvements in bit design were achieved after closing the model/measure/optimize loop. Through field testing, drilling parameter evaluation, and drilling simulation, a new 12-in. PDC bit was designed that established benchmark performances in the deep gas operations in the Ghawar field.
The successful development of the PDC bit in conjunction with the PRSS system led to record runs in the 12-in. build section. Casing-to-casing sections were drilled with an improved ROP of approximately 125%, compared to that of a conventional motor. This paper reviews the bit design and optimization process to develop the fit-for-purpose PDC bit that helped to improve the drilling performance, significantly reduce rig days, and enable early delivery of the wells in challenging deep gas drilling in Saudi Arabia.
Breakthrough PDC Technology Used in Saudi Arabia Deep Gas Wells to Significantly Reduce Drilling Time
Authors: Alvarez Octavio , Jamil Fouad , Qattawi Bassem , Olorode Akin O. 
Published: January 2010

Abstract
Drilling the intermediate sections in the deep gas fields of Saudi Arabia is challenging because of a long, intricate geological sequence consisting of hard carbonates (limestone and dolomite) interbedded with anhydrite. Historically, the primary operator has attempted to drill the section using both roller cone tungsten carbide (TCI) and polycrystalline compact (PDC) technology. PDC bits provided better penetration rate and durability, as compared to TCI bits. However, several PDC bits were required to drill the section, which increased the time needed for drilling and tripping at relatively deep intervals. The increased time exposes the well to risks when the hole is open for long intervals.
After further analyses and a systematic bit optimization process, three new PDC bit designs were created and used, which established new benchmarks in two of the deep gas fields. Meeting the objective of minimizing the number of bit trips by enhancing PDC bit performance and bit durability to drill longer intervals with a higher penetration rates required a new PDC bit technology in conjunction with optimized motor drive. To address the challenge, the operator, bit vendor, and other service companies worked together to develop an optimized solution to drill these sections.
The paper reviews the findings of the study in drilling the intermediate sections in two of the challenging deep gas fields. The study shows that PDC bit damage from encountering harder stringers was the primary impediment to achieving better performance. The impediment was overcome by implementing the new cutter technology and drilling simulation software to optimize the cutting structure design. The paper demonstrates the improvement in the deep gas fields in Saudi Arabia by comparing the performance of the most recent wells, in which the new technologies were implemented, to the earlier wells to illustrate the significant time and drilling cost reduction.
Combined Capillary Pressure and Resistivity Index Measurements in Tight Gas Sands Using Vapor Desorption Method
Authors: Dernaika M.R.. R. 
Published: January 2010

Abstract
This paper presents work on laboratory advances that have been developed to measure capillary pressure and electrical property measurements under low water saturation conditions. The paper discusses in some detail the various capillary pressure techniques utilized in the oil and gas industry and gives some insights on the Kelvin equation's applicability in tight gas sands. Detailed comparisons are shown between vapor desorption capillary pressure and mercury injection data a saturation offset that could be attributed to the non-wetting nature of the fluids and possible rock matrix alteration. The proposed calibration of the mercury data on tight sands is then considered for tight gas carbonate reservoirs.
Successful HPHT Application of Potassium Formate/Manganese Tetra-Oxide Fluid Helps Improve Drilling Characteristics and Imaging Log Quality
Authors: Al-Saeedi M. J. , Al-Khayyat B.. , Al-Enezi D.. , Aslan A.. , Luzardo J.. , Carrera C.. 
Published: January 2010

Abstract
Unconventional reservoirs associated with the presence of fractures have been identified in the Jurassic horizons in the Raudhatain field in North Kuwait. These reservoirs contain high-quality light oil and gas under HPHT conditions with associated H2S and CO2. The operator in this field is presently developing these gas/light oil reserves under the ‘North Kuwait Gas Development Project, The well discussed in this paper is one of a number of new production wells.
Historically, Jurassic wells in this field have been drilled using conventional barite-weighted, oil-based mud (OBM) with densities up to 18.5 ppg. However, the challenge to maximize the amount and quality of reservoir data collected and to reduce any impact on the formation caused by OBMs led to a search for an optimized water-based mud (WBM) system as an alternative.
A WBM formulated with saturated potassium-formate brine, weighted with manganese tetra-oxide, was selected for the following characteristics: higher base-fluid density, non-damaging nature, robust behavior in HPHT environments, and the possibility of better quality image logs.
The well reached 16,530 ft., in a 6–in. hole, with bottomhole temperatures around 280°F. The fluid was thermally resistant, exhibiting very low HPHT filtrate loss and highly stable rheological properties. The maximum fluid density was 16.2 ppg, with no evidence of settling of weight material, even after three days of static conditions.
A complete suite of logs was run successfully. The elemental capture spectroscopy (ECS), along with sonic and neutron porosity logs provided good data quality, and the image logs showed excellent resolution.
This paper will present all aspects of the planning, design, and utilization of this new drilling fluid. It will focus on lessons learned and conclude with recommendations for further optimization of the design of these drilling fluids.
Long-Lasting Experience In Environmental Protection During Sour Gas Reservoir Exploitation
Authors: Hrncevic L.. , Simon K.. , Kristafor Z.. , Malnar M.. 
Published: January 2010

Abstract
Since fossil fuels are still dominant sources of energy supply, in order to meet rising energy demand, petroleum industry is called upon not just to provide an effective management of oil and gas reserves, but also to manage to do that in safe and efficient manner with as low as practically possible ecological footprint. Consequently, also taking into account the fact that conventional oil and gas reserves are declining, petroleum companies are forced to develop and adopt new technologies to increase oil and gas recovery and to expand their upstream activities to still unexploited areas which often implies development of deep- buried oil and natural gas reservoirs characterized with unfavourable reservoir conditions such as high temperature and pressure and even certain amount of impurities.
Croatian experience with the natural gas production from deep- buried reservoirs is based on the development of several gas fields in the north- western part of Croatia. The development of the largest natural gas fields in Croatia, Molve, Stari Gradac and Kalinovac gas fields has begun at the beginning of the 1980's. The main characteristic of all the mentioned fields are extremely unfavourable reservoir conditions with reservoir depth over 3000 m, high initial reservoir pressures (over 450 bar), high temperature (180°C) and significant share of CO2, (10 - 54%) H2S (800 ppm) as well as some other non- hydrocarbon compounds like mercaptans (30 mg/m3) and mercury (1000 - 1500 µg/m3). In the last 25 years in the same region several other gas fields with the similar reservoir conditions were discovered and developed. Today, petroleum industry in Croatia has almost 30 years of experience in processing sour natural gas with well established methodology of auditing processing plant outlet gas influences on the environment. These experiences and future plans regarding this subject will be presented in this paper.
Finite Element Simulation of Downhole Stresses in Deep Gas Wells Cements
Authors: Nabipour A.. , Joodi B.. , Sarmadivaleh M.. 
Published: January 2010

AbstractDeep gas reservoirs are going to play more important roles in meeting growing demand of natural gas throughout the world. Due to extreme conditions of downhole stresses, pressure and temperature that occur in deep gas wells, maintaining cement mechanical integrity and zonal isolation have become critical concerns of industry during drilling, completion, and production of such wells. Cement sheath is expected to provide a flawless annular seal between casing and formation along the wellbore. However; cement failure cases which are being reported regularly show that there is still need for understanding extreme downhole conditions and the behavior of cement sheath experiencing such an environment. Although Uniaxial Compressive Strength (UCS) of cement is commonly regarded as the most important mechanical property of cement, recent theoretical and experimental results show that other mechanical properties of cement can be even more determinative in its failure.In this study, Finite Element Method (FEM), a widely-used robust numerical tool, is used for simulation of the downhole environment by modeling temperature, pressures, stresses, downhole materials and their interactions. Using this approach magnitude, direction and type of induced stresses in casing, cement, and formation have been determined. Furthermore; a series of sensitivity analyses was performed to reveal the effects of variation of various parameters such as casing internal pressure, differential horizontal stress and casing eccentricity, on the induced stresses in the cement sheath.Radial, tangential and von Mises stress profiles in the deep gas wells cements were investigated. Furthermore, the effect of casing internal pressure, differential horizontal stress and casing eccentricity were studied in the model. Results show that deep gas wells’ cements experience extreme amounts of thermal and mechanical stresses and special consideration is required in cement selection.
New Generation of MWD, LWD, and Image Logging Opens New Possibilities for Data Acquisition and Evaluation in Deep Gas Reservoirs
Authors: Malcore Eric C. , Qutob Hani , Kuchinski Robert 
Published: January 2010

AbstractDrilling deep gas wells poses a set of significant technical challenges, many of which approach or push the boundaries of equipment operational limits. The need for formation evaluation data in the deep gas reservoirs can be explained by the fact that relatively little is known about these reservoirs as data acquisition has been previously limited by temperature, pressure and hole size limitations of the instrumentation in older WL and LWD tools. Well bores of 5 in. or less may prohibit conventional logging-while-drilling (LWD) tools from acquiring necessary data. In addition, the consequences that high pressure has on mud systems which cause LWD and MWD data pulses to be compromised. Because standard LWD equipment had experienced numerous failures at such difficult down hole conditions, a new class of LWD and imaging tools was developed to address this challenging situation, This new class of tools opens new possibilities for data acquisition and evaluation in deep gas reservoirs. The paper will discuss:What technology exists today? The challenges in developing these technologies? The advantages and limitations of the technology.The measurements that will bring benefit in understanding the reservoirs such as real time imaging for fracture ID, (fracturing is a critical component as these reservoirs are rather tight and require natural or induced fracturing to enhance the permeability) The features and capabilities of the new tools will be discussed in this paper together with a brief introduction of few case studies representing the hot drilling in the North Sea, the heavy mud in China and the successful acquisition of high-quality data in a deep and slim hole well in Italy.
Hydraulic Fracturing Under Extreme HPHT Conditions: Successful Application of a New Synthetic Fluid in South Texas Gas Wells
Authors: Funkhouser Gary P. , Holtsclaw Jeremy , Blevins Joy J. 
Published: January 2010

Abstract
A new hydraulic fracturing fluid has been developed that is capable of stimulating high pressure/high temperature (HPHT) wells at 450°F without the need for cooling preflushes. Good viscosity at fluid temperatures as high as 450°F gives the synthetic fluid the potential to provide substantially better proppant placement than polysaccharide-derivative gels. The gelling agent is based on a terpolymer of 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, and acrylic acid that can be crosslinked with zirconium. The crosslink onset temperature can be varied over the range of 100 to 280°F, allowing optimization for particular well conditions. A delayed acting oxidizing breaker can be added to accelerate the gel's degradation, allowing rapid flowback and early production. The gelling agent is provided to the wellsite as a liquid-gel concentrate that is designed to be mixed and pumped with conventional fracturing equipment and procedures.
This paper discusses the laboratory testing, treatment design, and job execution leading to the successful hydraulic fracturing of two South Texas gas wells at depths of 23,300 and 18,900 ft with bottomhole static temperatures of 450°F and 433°F, respectively. The jobs were pumped as designed, with 190,000 lbs. of high-strength, resin-coated proppant placed in each zone at concentrations up to 9 lb/gal. Average treating pressures were 13,100 and 11,250 psi with slurry rates of 21 and 25.7 bbl/min, respectively. Cleanup was rapid, with gas flowing to the sales line the day after the treatment at a rate in excess of 4,000 MCF/D; in the case of the second well.