bluuebunny/crossref_metadata_2025 huggingface dataset:
Methods for Upscaling Diverse Rock Permeability Data for Reservoir Characterization and Modeling
Authors: Shafer John L. , Ezekwe Nnaemeka John
Published: December 2007

The primary sources of rock permeability data are cores and logs. Core-based permeability data are sampled from the reservoir at different scale from log-based permeability data. Consequently, porosity-permeability cross-plots from core plugs and logs are sensitive to the methods used in averaging the permeability data. For instance, arithmetic averaged core permeability data translated to log scale can be an order of magnitude greater than the core plug data at a given porosity. Using Dykstra-Parsons coefficient as a measure of reservoir heterogeneity, arithmetic averaging of permeability data is not suitable as the rock becomes more heterogeneous. Other methods such as geometric or harmonic averaging may be more appropriate.

Core heterogeneity below the vertical resolution of log NMR measurements has an impact on the methods used to calibrate NMR permeability data using core data. A method presented in this paper compares core permeability data with the NMR permeability data to account for sample volume differences utilizing high-density mini permeameter or high-density RCAL permeability data with different averaging techniques to simulate the vertical resolution of the NMR log.

This paper demonstrates the impact of averaging methods on upscaling permeability from core to log scale. Several unique methods for scaling up permeability data of heterogeneous rocks for reservoir characterization are recommended. These methods will generate more realistic characterization of reservoir models in terms of distributions of permeability property in the models.

The paper compared kh (permeability-thickness product) calculated from mini-DST tests to those calculated from core and profile (mini-permeameter) permeability data. The results of the comparisons are inconclusive. The kh from the mini-DST tests are not correlateable to those calculated from profile permeability data. The differences in kh values are traceable to uncertainty associated with depth shifts and the difficult task of ensuring that we are actually comparing data from the same depths or formation intervals.
Using a New Artificial-Lift System in Mexican Mature Oil Fields
Authors: Vann Roy R. , Gachuz-Muro Heron , Alcazar-Cancino Luis O. , Guerra-López Mauricio
Published: December 2007

Throughout Mexico there are many oil wells in danger of being plugged or abandoned. These mature wells could possibly be made economical again by employing a new oil well pumping system using cable instead of rods. This pumping method is designed as an alternative to conventional "rod and pump jack methods" utilized in oil wells. Instead of rods to convey the up and down stroke of the downhole pump, cable is used. In place of pump jacks, an electronic and hydraulic operated system is employed with no visible moving parts on surface equipment. The pumping method unconventional offers many options and advantages that conventional pumping does not offer.

The system is designed to operate safely and environmentally pleasing with low noise operation capability and a clean wellsite appearance with no oil leakage. In addition, an economic value is recognized when maintenance is required. A special cable unit is brought out to reel up and repair the downhole pumping assembly and return it to bottom; no workover unit is needed.

This method has been developed and tested in Tyler, Texas for approximately seven years. Recent results in Mexico have shown many advantages. This paper presents various aspects (evaluation, development, working principle, etc) of this system and the field test results in Mexican Mature Oil Fields. The versatility of its characteristics has allowed us to maintain oil rates and reduce operational costs. This system discusses its difference with "conventional methods" and impact on production behavior.
The Effectiveness of Geochemical Technique for Evaluation of Commingled Reservoir: Case Study
Authors: Nengkoda A. , Widojo S. , Mandhari M. S. , Hinai Z. , Khan T.
Published: December 2007

The X gas field of PDO is currently contributing of Oman's gas requirements for LNG export. The field is producing from the rich gas-condensate bearing Reservoir A and lean gas bearing Reservoir B and Reservoir C sandstone. The total number of wells until to date is 23 development wells drilled in the field, of which 11 wells are on production, 6 wells produce from Reservoir A only, 1 well from Reservoir B only, 3 are commingled Reservoir A, B and C, 1 well from Reservoir A and C, and last, 1 well from C. The average formation split from the field predicted 45% Reservoir A, 20% Reservoir C and 35% Reservoir B, and in specific is vary from well to well and however it is depend on the drawdown. The primary surveillance tool is used to allocate a relative production for two reservoirs by utilizing a MPLT surveys. And recently, a campaign of multi-phase flow meters coupled with PLT's was initiated. Gases in Reservoir B and C reservoirs of Oman have very different carbon isotope character than those in Reservoir A. These differences are unique and can be used to calculate mixing proportions of commingled production. The proposed solution to this problem was the derivation of two and three case models that accounts for variable isotope and composition characteristics, and trending in which all such data could be correlated. The effectively of this geochemical technique is captured from this study.
Hierarchic Modeling and History Matching of Multiscale Flow Barriers in Channelized Reservoirs
Authors: Li Hongmei , Caers Jef
Published: December 2007

Channelized reservoirs often consist of multi-scale architectures containing large-scale channel belts, middle-scale single channels and small-scale channel infill components. These architectural elements are defined between bounding surfaces. Along these hierarchical bounding surfaces, thin shale drapes may be present as flow barriers that compartmentalize the reservoirs. Since the distribution of shale drapes is dominated by these bounding surfaces they themselves form a multi-scale reservoir heterogeneity. Characterizing the distribution of these multi-scale flow barriers calls for a hierarchical modeling and history matching approach to integrate all data available. In this hierarchic approach the large-scale reservoir architecture is modeled first, the shale drapes are then simulated within this architecture framework.

The reservoir architecture modeling in this paper involves defining channel deposition fairways (valleys) based on seismic data, modeling long sinuous channels and placing them into defined fairways such that all data are matched. This paper adopts a stratigraphic-based modeling approach. In this stratigraphic-based approach, individual channels are simulated using the YACS method (Alapetite et al., 2005). This method is fast and conditions to well data under the assumption that channel sand can be identified in the well data. To stack multiple channels reproducing a desirable stacking pattern, the migration ratio and overlap ratio are used as input parameter of the simulation process. Once the large-scale reservoir architecture is modeled, the bounding surfaces are record, next, the shale drapes are simulated along these surfaces using multiple-point statistics techniques. To match the production data, channel location and the number of channels are perturbed using the gradual deformation method, the continuity of shale drapes is perturbed using the probability perturbation method.

A 3D synthetic example is presented to demonstrate this modeling approach: the multi-scale shale drapes are modeled and perturbed while the reservoir geological concepts are preserved. This hierarchic modeling approach allows integrating different data at their relevant scale.
Humans Are Not Responsible for Global Warming
Authors: Chilingar G. V. , Khilyuk L. F.
Published: December 2007

The global drivers that determine the Earth's climate are: (1) solar radiation as a dominant energy supplier to the earth, (2) the Earth's outgassing as a major supplier of gasses to the hydrosphere and atmosphere, and, (3) possibly microbial activities generating and consuming atmospheric gases at the interface of lithosphere and atmosphere. The authors provide quantitative estimates of the scope and extent of their effects on the Earth's climate. Comparison of these estimates with the corresponding anthropogenic effects shows that the human-induced climatic changes are negligible with respect to global forces of nature. One should not ignore the fact that peaks in solar irradiation precede peaks in CO2 concentration. Using the adiabatic model developed by the famous Russian Scientist, Dr. O.G. Sorokhtin, the authors show that the increase in CO2 concentration in atmosphere will result in cooling rather than warming. Thus, the attempts to alter the global climatic changes (and drastic measures prescribed by the Kyoto protocol) have to be abandoned as meaningless and harmful.
Experimental Investigations of Ultrasonic Waves Effects on Wax Deposition during Crude-Oil Production
Authors: Towler Brian F. , Chejara Ashok Kumar , Mokhatab Saeid
Published: December 2007

One of the problems that plagues oil companies is the deposition of wax or paraffin inside pipelines. The present invention is a method for mitigating the wax deposition during crude oil flow in a well-bore or pipeline. The method comprises positioning one ultrasonic frequency generating device adjacent to the production tubing walls and producing one ultrasonic frequency thereby disintegrating the wax and inhibiting the wax from attaching to the production tubing walls. Experiments were done to measure the effect of ultrasonic waves at a frequency of 120 kHz on wax deposition during crude oil flow in a pipeline. In this paper, all the experimental results are described. Some reduction in wax deposition was also achieved due to the ultrasonic waves. Further work is required to identify the optimum frequencies.
The Extraction of Mud-Stuck Tubulars Using Vibratory Resonant Techniques
Authors: Gonzalez Ozzie , Bernat Henry , Moore Paul
Published: December 2007

Stuck pipe has been identified as the largest single contributor to non-productive drilling time. The use of resonant vibration as a means of freeing stuck tubulars from a well bore has been demonstrated to be effective in both Drilling and Workover environments and has the potential to provide almost immediate results in many day-to-day applications. The challenge for the future is to further explore both proven and potential applications of this technology in order to evaluate the benefits and reduce the unknown associated with the technology. The long term industry benefit will be a new approach to stuck tubular recovery available in the form of superior technology that addresses real needs while substantially reducing costs. The technology offers the benefits of being quick and easy to apply, operations are conducted from surface with no downhole intervention, and results may be achieved very quickly. Good success in open hole work could mean that this technology could become the procedure of choice in virtually all drilling operations. In workover operations, the technology may accomplish the same results in hours that typically require days by current standards.
Quantitative Optimization of Offshore Fire and Gas Systems Design Using IEC 61511 (ANSI/ISA-84)
Authors: Raju C. R.
Published: December 2007

Application of performance-based standards viz. IEC 61508 and IEC 61511 in offshore FGS has been a matter of debate since the inception of these codes. Most of the safety practitioners are reluctant to apply these codes to offshore FGS due to reasons like FGS is a mitigation layer, difficulty in achieving even SIL 1 in gas detection loops, scarcity of certified components and difficulties of quantification. Lack of importance of FGS in onshore installations is also one reason in the case of onshore installations.

FGS is a protection layer in offshore oil and gas production offshore platforms as important as important as ESD systems. FGS is a most important mitigation as well as ESD IPL too. Quantification techniques of IEC 61508 and IEC 61511 like SIL determination and SIL evaluation can be effectively used in FGS of offshore platforms. This will lead to more efficient design of FGS systems than designs based on API 14 series and other prescriptive codes and user policies based on qualitative judgments.
Reservoir Technical Limits: A Framework for Maximizing Recovery from Oil Fields
Authors: Smalley P. Craig , Ross Bill , Brown Chris E. , Moulds Tim P. , Smith Mike J.
Published: December 2007

Maximizing recovery is an important part of responsible asset management and of optimizing value from an incumbent resource position. BP's Reservoir Technical Limits (RTL™) process has proved highly effective at estimating oilfield maximum recovery potential and identifying/prioritizing specific activities to help deliver it. This paper describes the process and examples of how it has worked and can be applied.

RTL incorporates a conceptual framework with supporting software, designed to stimulate and structure a conversation with the asset team in a workshop environment. Key ingredients are: in-depth knowledge/experience of the cross-disciplinary asset team; trained facilitation; cross-fertilization from external technical experts; a toolkit to encourage innovation in a structured and reproducible manner. The RTL framework represents recovery factor as the product of four efficiency factors: Pore-Scale Displacement (microscopic efficiency of the recovery process); Drainage (connectedness to a producer); Sweep (movement of oil to producers within the drained volume); Cut-offs (losses related to end of field life/access). Increasing recovery involves trying to increase all of these efficiency factors. RTL builds upon the opportunity set already contained in the Depletion Plan. New opportunities are identified systematically by comparing current/expected efficiency values with data from high-performing analogue fields, seeding ideas with checklists of previously successful pre-screened activities. The identified opportunities are prioritized based on size, cost, risk, timing and technology stretch, and then validated by recovery factor benchmarking: (a) internally, comparing bottom-up (summing opportunity volumes) and top-down (from efficiencies) values; and (b) externally, by comparison with analogue fields.

The result is a prioritized list of validated opportunities and an understanding of how each activity affects the reservoir to increase recovery. The activities (and any required new technologies) are valued in terms of the resultant incremental barrels. Case studies demonstrate the effectiveness of RTL in stimulating activity in individual fields and focusing corporate technology resources into high-impact areas.

The RTL framework is a significant innovation towards increased recovery factors. It is a new medium to focus the talent of the asset team onto life-of-field value, generating an opportunity set of real activities that the team can start to progress immediately.
Characterization of Oil/Water Flows in Horizontal Pipes
Authors: Vielma M. , Atmaca S. , Sarica C. , Zhang H. -Q.
Published: December 2007

The dynamic characteristics of oil-water flow systems have not been fully understood. The need for improved design methods has led researchers towards its continuous investigation. The objective of this study was to characterize oil-water flow in horizontal pipes. The tests were conducted in a 2-in. horizontal test section using Tulsa City tap water and a mineral oil (density = 0.85 g/cm3 and viscosity = 15 cp) with superficial velocities ranging from 0.025 m/s to 1.75 m/s. Various data were acquired on flow patterns, pressure drop, phase fraction and droplet size as function of flow patterns and were used in characterization of the flow and performance evaluation of an oil-water model. A high speed video camera was used to identify flow patterns, measure droplets and ten conductivity probes were used to obtain phase distributions.

New experimental data on pressure drop, holdup, phase distribution and droplet size distribution in oil-water flows are presented. Three probabilistic distributions were tested for fully dispersed flows. Sauter Mean Diameter (SMD) analysis were conducted across the pipe diameter. Droplet size data were used to evaluate existing models such as Hinze1, Kubie and Garner2, Angeli and Hewitt3, and Kouba4. An empirical correlation to predict the SMD profile of droplets across the pipe cross section was developed for flow pattern of dispersed oil in water and water (D o/w & w). Log-normal distribution was the best probabilistic distribution for representing the data for fully dispersed systems. The empirical correlation gave acceptable results. Model comparisons revealed that none of them could accurately represent the experimental data.

The new data can lead to better modeling and design of dispersed systems and the new information on droplet sizes can have significant impact on separator design. Moreover, the interpretation of production logs in horizontal wells heavily relies on the flow behavior.
Consistent Black-Oil PVT Table Modification
Authors: Singh Kameshwar , Fevang Øivind , Whitson Curtis H.
Published: December 2007

This paper presents a physically consistent approach to modify black-oil PVT tables for (1) eliminating, in some cases, so-called negative compressibilities, (2) extrapolating saturated and undersaturated properties to conditions beyond the limits of original PVT tables, and (3) guaranteeing physical consistency of gas and oil properties as a critical condition is approached.

For a number of reasons a black-oil PVT table may contain inconsistencies that result in non-physical behavior in reservoir simulators, sometimes leading to slow run times and, sometimes, premature run termination. Physical inconsistencies can even arise when the black-oil PVT table is created by a physically-consistent EOS model. Black-oil behavior can also be inconsistent as a result of the method used to create the tables – e.g. correlations, conversion of laboratory data, or using EOS models where gas and oil phases are not in thermodynamic equilibrium.

Three main methods are developed in the paper. First, an analysis of negative compressibilities is given and an approach to eliminate the problem is proposed. Negative compressibilities can arise because derivatives are held constant from one pressure table point to the next, inconsistent with the pressure-dependent evaluation of properties themselves.

The second contribution of our paper is a method to extrapolate an existing black-oil table to higher saturation pressures than found in the original table. Extrapolation is possible to any higher pressure – including a critical ("convergence") pressure where phase properties become identical. The proposed method uses a piecewise-linear log-log relationship between black-oil (surface gas and surface oil) K-values and pressure.

Our final contribution is a consistent method to calculate saturated and undersaturated black-oil PVT properties at interior and extrapolated pressures to those in the original table. A cubic EOS and the LBC viscosity correlation methods are used to provide physical consistency, even approaching a critical condition where gas and oil properties must become equal.
Vertical Sweep Evaluation in the Lost Hills Diatomite Waterflood Using Carbon/Oxygen Logs
Authors: Badruzzaman A. , Badruzzaman T. , Morea M. F. , Julander D. J.
Published: December 2007

We discuss our experience to date with the Carbon/Oxygen logging technique to determine vertical sweep in Belridge Diatomite in the Lost Hills Field. We describe early interpretation challenges with overly optimistic saturation estimation. This required in-house Monte Carlo modeling to understand the tool response in very high porosity reservoirs. A newer vendor algorithm, however, underestimated the oil saturation. In-house test algorithms were then developed with significantly more accurate estimation of the oil saturation from a centralized-detector C/O tool in water-filled boreholes; results reported here are primarily for this tool. The C/O technique is also being tested in producers using the corresponding focused tool; we include an example of a successful test of the tool in an uperforated well. The paper identifies further development needed to use C/O techniques, especially the focused tool, optimally in either monitor or producer wells in diatomite.
A New Philosophy of R&D Management: Combining Third-Generation R&D Management With Technology Road Mapping (TRM)
Authors: Li Xianqi , Dou Hong'en , Chen Changchun , Chang Yuwen , Qu Debin , Yan Jianwen
Published: December 2007

This paper presents a new philosophy of research and development (R&D). it is combined the mode of third generation R&D management (Philip A. Roussel, Kamal N.Saad and Tamara J. Erickson, 1991) with technology road maping (TRM) (Jonah M. Duckles, and Edward J. Coyle, 2002, Alain Leger, Fausto Giunchilia, Ana V.Zhdanova and Niana Maynard, 2005). Main management system of the third generation R&D management and its functions, advantages and application of TRM of petroleum technology R&D were described in the paper. At the same time, milestone's elements of technology R&D and RTM's construction are discussed. This paper also point out how to keep company business target in accordance with the technology development target through identifying and prioritizing technology investment decisions, and repositioning company technology capabilities. The visions of the future technology scenario planning and translating the TRM to a technology strategy can be put forward. The methodologies, tools and templates of TRM are also presented in the paper, prioritizing technology capability and upgrading and sharing the technology future. Therefore, a chain was established among the technologies, products and services development plans, and linking of technologies to business drivers and strategy targets in order to reduce the risk of R&D of the technology. Finally, the paper proposes formulation of the TRM, and it also emphasizes that the RTM is an excellent management tool for analyzing and prioritizing potential future technology acquisition. At present, this method has been implemented to the R&D management in PetroChina.
Enhanced Mechanical Earth Modelling and Wellbore Stability Calculations Using Advanced Sonic Measurements—A Case Study of the HP/HT Kvitebjorn Field in the Norwegian North Sea
Authors: Wendt Anke S. , Kongslien Marit , Sinha Bikash K. , Vissapragada Badarinadh , Newton Adrian , Skomedal Eiliv , Renlie Lasse , Pedersen Erik Sandtorv
Published: December 2007

Geomechanical interpretations of inhomogeneous anisotropic materials are enhanced by three dimensional (3D) sonic measurements that provide compressional, fast shear, slow shear, and Stoneley wave slownesses in (an)isotropic drilled formations.

We investigated the Kvitebjorn high pressure high temperature (HPHT) gas/condensate field for enhanced Mechanical Earth Modelling, and wellbore stability analyses using three-dimensional sonic measurements in overburden and reservoir formations. Kvitebjorn field is situated on the Norwegian continental shelf west of the Viking Graben

In the HPHT Kvitebjorn field, major development challenges are the determination of the drawdown rate and the maximum depletion for optimum production while maintaining rock integrity. These challenges are directly related to the effect of changes in reservoir pressure on the in-situ formation stress state. Using advanced processing of sonic data, we estimated the amount of stress anisotropy, stress orientations, and stress magnitudes at particular reservoir intervals. These stress data together with measured in-situ minimum horizontal stress values were used to calibrate horizontal stress logs perviously estimated in the MEM. Furthermore, we constrained rock elastic properties (deformation, strength) using sonic slownesses and elastic shear moduli calculated from the sonic dataset. These data were later used to estimate rock strength and the onset of wellbore deformation. The two approaches allowed us to calculate (1) isotropic rock properties from the sonic slownesses, and (2) vertical and horizontal rock properties from the calculated shear moduli.

Validity of the so-calibrated MEM was subsequently tested estimating wellbore stabilities based on the isotropic rock property data, and the vertical and horizontal rock property data sets. In each case, the model was able to accurately reproduce the events observed during drilling.

The work that we present here is intended to open a new direction for geomechanical modelling: To demonstrate a new measurement allowing practical consideration of rocks as an anisotropic material, and to better constrain the effective stress ratio.
Key Aspects of Project Design for Polymer Flooding
Authors: Wang Dongmei , Seright R. S. , Shao Zhenbo , Wang Jinmei
Published: December 2007

After a pilot site meets the screening qualifications for polymer flooding, the injection measures and the injection formula are key points when designing a polymer flood. This paper places special emphasis on some new design factors that were found to be important during extensive experience during polymer flooding. These factors include (1) recognizing when profile modification is needed before polymer injection and when zone isolation is of value during polymer injection, (2) establishing the optimum polymer formulations, injection rates, and individual well production allocations, and (3) time-dependent variation of the molecular weight of the polymer used in the injected slugs,

At Daqing, polymers with molecular weights from 12 to 38 million Daltons were designed and supplied to meet the requirements for different reservoir geological conditions. The optimum polymer injection volume varied around 0.7 pore volume (PV),1 depending on the water cut in the different flooding units. The average polymer concentration was designed about 1,000 mg/L, but for an individual injection station, it could be much more.2,3 The injection rate should be less than 0.2 PV/yr, depending on well spacing. Additionally, the project design should follow certain rules when allocating the injection rate and production rate for individual wells.
Aluminium Alloy Tubulars—Assessment for Ultralong Well Construction
Authors: Gelfgat Mikhail Ya. , Basovich Vladimir S. , Adelman Alex , Hansen Brikt R.
Published: December 2007

Remaining oil and gas resources situated in easily accessible reservoirs are continuously dwindling, forcing the drilling industry to extend the range of possible targets for production activity to deposits located at considerable depths and a long way from drilling sites. With significant increase in the price of oil, a large number of deposits whose development was previously considered non-economical became suitable for exploitation. Most of these deposits lie offshore and need a borehole of considerable length to reach them from land. Recently the industry experienced a rapid increase in TMD of ERD wells, and reached the record of 11,282m TMD at Sakhalin-1 project in Russia. Several other ultra-long ERD wells include 11,278m TMD (10,728 m displacement) at Wytch Farm M-16 in UK; 11,184 m TMD (10,585 m displacement) at CN-1 in Argentina; 9,082m TMD in Visund, North Sea and etc. Drilling of such long wells, where conventional technology is stretched to its limits, is extremely challenging. Most critical of such challenges is increase in weight of the drill string, leading to considerable growth of drag. In ultra-long wells, the drag may rapidly reach values making it impossible to continue drilling without either reducing frictional forces or reducing the gravity force component acting between the contact surfaces. Reducing the weight of the drill string provides great benefits in ERD operations.

One of the solutions for extending the limits of horizontal well drilling is the replacement of conventional steel drill pipe with light alloy drill pipe. This pipe contains a number of superior properties offering important benefits. The most important of them is decrease of drag and torque in horizontal sections, which reduce the possibility of buckling initiation. Aluminium drill pipe (ADP) has extensive productive operational experience in drilling various types of wells. One of the outstanding achievements gained with utilization of ADP was

reaching the world record depth of drilling at Kola Ultra-deep Well in 1990. The drilling of this well was performed by use of downhole motors with simultaneous drill string rotation, which predominantly consisted of ADP. The drilling of this well presented a huge amount of operational experience, which in turn was effectively used in drilling less complicated wells. In fact, ADP usage averaged about 80% of all drill pipe in operation in the Soviet Union by 1980-s.
A New Inversion Method To Interpret Flow Profiles from Distributed Temperature and Pressure Measurements in Horizontal Wells
Authors: Yoshioka K. , Zhu D. , Hill A. D.
Published: December 2007

The increasing deployment of distributed temperature and pressure measuring devices in intelligent well completions is providing the means to monitor the inflow profiles of wells without any well intervention. If the profiles of pressure and/or temperature are affected by the inflow profiles of the various phases being produced, it is possible to estimate these flow profiles by inverting the measured temperature and pressure profiles. This inversion process is particularly challenging for horizontal wells because the pressure drop along the well is usually small, and temperature changes, caused primarily by Joule-Thomson effects, are also small.

This paper presents an inversion method that interprets distributed temperature and pressure data to obtain flow rate profiles along horizontal wells. The inversion method, which is based on the Levenberg-Marquardt algorithm, is applied to minimize the differences between the measured profiles and the profiles calculated from a forward model of the well and reservoir flow system.

We present synthetic and field examples in this paper to illustrate how to use the inversion model to interpret the flow profile of a horizontal well. The synthetic examples show that even with single-phase oil production, the inflow profile can be estimated in many cases with the inversion method developed. The method is even more robust when water or gas is produced along discrete intervals in an oil production well because of the unique temperature signature of water or gas production. We applied the inversion method to temperature and pressure profiles measured with production logs in a North Sea horizontal oil producing well. The method successfully inverted pressure and temperature profiles and the profiles of oil and water flow rates determined compared well with the flowmeter derived profiles.
A Geomechanical Facies-Based Approach to Optimize Drilling and Completion Strategy of an Unconsolidated Sandstone Reservoir, Saudi Arabia
Authors: Raba’a Ali S. , Abass Hazim H. , Hembling Drew E. , Finkbeiner Thomas
Published: December 2007

Drilling horizontal wells, single and multilateral, is nowadays common practice for Saudi Aramco in most of its oil and gas reservoirs (clastics as wells as carbonates) in Saudi Arabian fields. This study highlights the application of a geomechanics study to evaluate well stability drilled into a friable eolian oil-bearing sandstone reservoir. Saudi Aramco's reservoir management was eager to find the optimum mud type and azimuthal direction to place long reach horizontal wells, so as to minimize the risk of stress-induced borehole breakouts, optimize drilling mud weights, aid in making informed decisions about adequate completion design, and ensure sustainable production under depletion mode.

The reservoir rocks in this field are characterized as a "wet" eolian depositional system with four distinct depositional facies: dune, sand sheet, paleosol and playa. Grouping the lithology into these four recognizable depositional facies significantly enhanced the understanding of facies dependent rock properties and related wellbore integrity. Hence, a critical objective of the study was to combine the knowledge of reservoir and material properties with detailed analyses of the present day in situ stress field. Upon determination of the in situ stress field in the study area, wellbore stability in the principle horizontal stress directions (Shmin and SHmax) was calculated and compared and the resulting optimum direction was recommended. The effect of mud on rock strength was evaluated and the mud type that caused less rock-strength reduction was selected.

The study concluded that under undepleted conditions horizontal wells should be drilled with oil-based mud parallel to the field-derived maximum principal horizontal stress (SHmax) azimuth in order to maximize borehole stability and minimize required mud weights during drilling and completion. The results from this detailed study will be incorporated into Saudi Aramco's reservoir management decision tree, in order to maximize wellbore integrity during drilling and completion such that least damage occurs to the reservoir during drilling and in-gauge hole conditions for successful sand control completion deployment can be maintained.
The Design, Construction, Implementation, and Integration of a New Petroleum Engineering Campus in the Middle East
Authors: Platt F. M. , Fahes M. M.
Published: December 2007

This paper concerns the planning, construction, implementation, and integration of new state-of-the-art teaching laboratories for Petroleum Engineering at Texas A&M University at Qatar, a new international campus in the Middle East.

The results are seven laboratories designed to teach and support seven topics covered under the university curriculum for Petroleum Engineering at Texas A&M University. The laboratories were designed and built for the new campus in Doha, Qatar, to instruct the student in team programs and cover the following topics: Geology (both general and advance reservoir characterization)Core PetrophysicsFluid and Gas PVT PropertiesDrilling SystemsProduction (to include fluid measurement in up to three phases)Well Control (to include construction and implementation of a drilling rig floor for simulation)3-D Simulation Room for Reservoir Characterization
Operating Multiphase Helicoaxial Pumps in Series to Develop a Satellite Oil Field in a Remote Desert Location
Authors: Saadawi Hisham
Published: December 2007

Abu Dhabi Company for Onshore Oil Operations (ADCO) has recently developed one of its satellite oil fields. The field is located in a remote desert location onshore the Emirate of Abu Dhabi, in the United Arab Emirates (UAE). The development concept is based on multiphase pumping and the entire field was developed using multiphase pumps.

Two helicoaxial pumps are used to pump 10,000 b/d of crude oil with associated gas and produced water to the host facilities in a nearby field some 30 km away. The pumps are installed in series. The pumps were commissioned successfully in 2006 and have been operating since then.

Huwaila field is the first and only oil field in the world where two multiphase helicoaxial pumps are operated in series. This paper describes the design, testing and operational aspects of this unique experience.
Wellbore Isolation Intervention Devices Utilizing a Metal-to-Metal Rather than an Elastomeric Sealing Methodology
Authors: Mackenzie Gordon , Garfield Garry
Published: December 2007

Metal-to-metal sealing technology is a medium-to-high expansion, innovative type of seal that utilizes expanding metal to achieve a fully formed pressure barrier on a tubular wall. The presented material will highlight the evolution of common oil and gas industry wellbore isolation/intervention devices that take advantage of a sealing system with an expandable metal-to-metal approach rather than a more traditional/conventional elastomeric packing element style.

The applications for the technology within our industry are wide ranging even reaching through areas such as completions, liner hangers, sand control, and flow control. Initially the development was centered around proving the technology from a predominantly live well intervention philosopy focusing on bridge plugs and straddles. The replacement of an elastomeric sealing element applies in many environments; however, the metal-to-metal seal is designed with an extraordinary seal performance envelope that cannot be achieved by conventional elastomeric seals and is perceived to be particularily desirable within the realms of hostile, high pressure, high temperature and geothermal markets. Many common failures in these type of environments leading to NPT issues will be shown to be mitigated with a technology step change in seal design.

The results of the learning curve knowledge gained from both the design and implementation phase of the project will be compiled and introduced. Case histories to highlight the effectiveness and uniqueness of the technology will be disseminated in order to show the differentaiting technology between the use of a metal sealing methodology when compared with that of an elastomeric approach.

Evaluation of the metal-to-metal sealing technology will offer a guide in order to help in the construction of a set of criteria to fully interpret the benefits and selection of a metal sealing technology over an elastomeric seal. The contributions to our industry will be shown through the features and benefits of the metal-to-metal sealing technology over an elastomeric sealing system.
Experimental Determination of Relative Permeabilities for a Rich Gas Condensate System Using Live Fluid
Authors: App J. F. , Burger J. E.
Published: December 2007

Measurement of gas and condensate relative permeabilities is typically performed through steady state linear core flood experiments using model fluids. This study addresses experimental measurement of relative permeabilities for a rich gas condensate reservoir using a live, single-phase reservoir fluid. Using a live, single-phase reservoir fluid eliminates the difficulties in designing a relatively simple model fluid which replicates the complicated thermodynamic and transport properties of a near critical fluid. Two-phase flow tests were performed across a range of pressures and flow rates to simulate reservoir conditions from initial production through depletion. A single-phase multi-rate experiment was also performed to assess inertial, or non-Darcy, effects. Correlations were developed to represent both the gas and condensate relative permeabilities as a function of capillary number. A nearly 20-fold increase in gas relative permeability was observed from the low to high capillary number flow regime. Compositional simulations were performed to assess the impact of the experimental results for vertical and horizontal well geometries.
Reservoir Model Uncertainty Quantification Through Computer-Assisted History Matching
Authors: Yang C. , Nghiem L. , Card C. , Bremeier M.
Published: December 2007

Quantification of uncertainty in production forecasting is an important aspect of reservoir simulation studies. The uncertainty in the forecasting stems from the uncertainties of various model-input parameters, such as permeability, porosity, relative permeability endpoints, etc. Traditionally, the outcome of history matching is a set of parameter values that result in a good match of the historical production data. Clearly, the history matching process will be even more valuable if the uncertainties of these model-input parameters can be quantified in the process.

In this paper, we present a systematic history matching approach to condition a reservoir model to production data and quantify the uncertainties of history matching parameters in terms of probability density functions. The new approach utilizes experimental design and multi-objective global optimization techniques. More specifically, for a given list of uncertain parameters, the history matching process is treated as a combinatorial optimization problem to find the best combination of these parameters to achieve the minimum history match error. The combinatorial optimization problem is solved by applying a hybrid metaheuristic method that combines evolutionary algorithms, Tabu search, and experimental design techniques. In the optimization process, reservoir models containing different combinations of parameter values are automatically generated to cover a wide range of possibilities based on the principles of experimental design and Tabu search. The search space of the optimization problem is gradually reduced by adopting the natural selection mechanism to discard parameter values that do not fit field data. Finally, the posterior probability density functions of the uncertain parameters are estimated by applying Bayesian theory.

The proposed methodology is demonstrated in a real field case study of a complex oil field, which has 12 production wells and 10 years of production history. Some of the wells in the reservoir are found to be difficult to match using the traditional manual history matching approach. After applying the new approach, all the well histories are successfully matched. More importantly, the posterior probability density functions of uncertain parameters are estimated in the history matching process. The results can be further used to quantify the uncertainty in the production forecasting of follow-up recovery processes.
The Virtual Well: Guidelines for the Application of Dynamic Simulation to Optimize Well Operations, Life Cycle Design, and Production
Authors: Mantecon Juan Carlos
Published: December 2007

The rapid uptake of transient multiphase flow simulation of wells demonstrates the recognised value to the Industry of this relatively new technique. In offshore, subsea and deepwater well locations, and in long horizontal, multi-layer, multi-lateral, big-bore and complex well completions, Industry can benefit from dynamic simulation for sound engineering design, and optimisation of costs and production.

Dynamic simulation provides the possibility of building a virtual well that can be used to analyse "what if" case scenarios and predict specific results. It is an excellent tool to understand transient well behaviour and determine the optimum process to eliminate or minimise potential transient problems. It does not replace NODAL® analysis but fills a gap where NODAL® analysis techniques cannot provide solutions. Once the dynamic well model is validated it can also be used as an implicit gauge and/or a virtual DTS during production/injection operations.

This paper details some applications, and provides guidelines for the proper use of dynamic simulation in key areas including: well clean-up, well kick-off, watercut limit, flow stability, flow assurance (hydrates), gas lift requirements, large tubing ID flow, production optimisation, and well test equipment sizing.

Well Dynamic Simulation is a useful tool that can be used during FEED and at any stage of the well life cycle to "virtually" run through a complete case scenario and predict the well multi-phase flow behaviour (including trends and profiles of liquid hold-up, pressure and temperature), providing valuable information to optimise technical, operational and HSE integrity during design and operation of production systems.
More Rapid and Robust Multiple History Matching With Geological and Dynamic Uncertainties: Heavy-Oil Case Study
Authors: Poncet J. , Vincent G. , Inizan M. , Henriquel P. , Jannes P.
Published: December 2007

The generation of reservoir simulation models that match field production data has been and is still a long-time industry challenge, not only for the time spent on history matching studies but also because of the non-uniqueness of the solution. This paper presents a new approach called "Hybrid Models" to accelerate this process and get more realistic history match models. Hundreds of stochastic possible geological models are produced and tested in regard to the dynamic data. The Hybrid model is a composite geological model, not only constrained by the initial well data but also with selected parts of the first realizations matching around some wells. This technique allows a relatively quick history matching process and results in a series of matched geological models.

This process was applied in part of a heavy oil field (14 horizontal wells in fluvial reservoirs were considered), after 3 years of production. The objective was to explain and reproduce the high water-cut, oil rates, GOR and bottom-hole pressures in this part of the field. A complete uncertainty workflow was applied with sedimentological and petrophysical uncertainties as well as fluids and dynamic uncertainties. Results showed that static uncertainties were essential to get a coherent match and "Hybrid Model" technology was applied with success.

The Hybrid model technique gives several matched geological models. All models have been carried out through forecasting keeping the present development plan, evaluating the potential impact of remaining static uncertainties. Dynamic uncertainties were also considered on one geological matched model. Several combinations of dynamic parameters have been computed to keep a match. Corresponding models have been transferred through forecasting. Final conclusions were that at fixed development plan, dynamic uncertainties are more to be considered and combined for the forecast than static ones.

The use of the "Hybrid models" technique and the integration of static and dynamic properties as matching parameters have been shown to be efficient to produce accurate multiple production history matched models. From those models, it has been possible to quantify the remaining uncertainties in terms of future production and to propose new developments.
Utilizing Geosteering in Horizontal Wells to Maximize Value in Mature Fields, Central Sumatra, Indonesia
Authors: Moestopo Hendar S. , Jacobs Gary W. , Nur Hasyim M. , Reinhold Mark R. , Pramudyo Yuni B. , Purwanto Komar E.
Published: December 2007

Geosteering techniques are used to maximize exposure of well bore to pay zones. Accurate well bore placement is vital to the success of horizontal well drilling. The last 3 years has seen 50 horizontal wells drilled by PT Chevron Pacific Indonesia in the Central Sumatra Basin of Indonesia. We have found that geologic uncertainty is the largest risk to successfully drilling these wells. Small faults that cannot be accurately mapped with existing seismic and with displacements of 15 feet or less are commonly found and present a challenge to stay in the target. Obviously, the loss of objective section reduces the effective drilled lateral footage of a well and thereby affects productivity.

One key to achieving desired lateral footage drilled is understanding the response of resistivity and gamma ray while drilling. That, combined with cuttings analysis, rate of penetration (ROP), and other drilling parameters, permits the response and reaction to geologic uncertainty to be managed more effectively.

Monitoring these data as acquired in real time with reference to pre-job modeling, provides the key elements for intelligent decision making on trajectory decision.

This paper will share specific examples of the challenges we have faced and how we recognize and react to geologic uncertainty while drilling.