bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Exploration Areas using Extension of 3D Techniques in Mature Areas
Authors: Villaroel V. , Garcia E. , Ronny R.
Published: December 2007

The goal of this paper was to evaluate and incorporate new hydrocarbon reserves in exploration areas nearby to highly developed fields, via extrapolation of 3D seismic attribute techniques into a 2D seismic grid. The project evaluated an area of approximately 180 Km2 located to the west of Budare field, using sequence stratigraphy interpretation techniques in about 100 line Km of 2D seismic acquired in 1966, as well as interpretation on aproximately 100 Km2 of 3D seismic gathered in 1994. Petrophysical and reservoir data were analyzed along with the 3D seismic in the field area using computer-integrated systems, to provide the link between the seismic and the field arquitecture. This information was then extrapolated to the 2D seismic grid and allowed to determine the possible direction and geometric extension of sand channels in the exploration area. This interpretation helped to identify several stratigraphic and structural plays in the new area, composed mainly by upper Oligocene - Miocene fluvio deltaics sands of about 200 feet in thickness at a maximum depth of about 4000 feet. Total estimated reserves on this plays is on the order of 30.7 MMB with gravity ranging in the order of 35 API, representing about 30% of the remaining reserves in the Budare field. The incorporation of these plays increased drastically the potential of the area due to the characteristics of the crude and reservoir, along with their closeness to the existing production facilities.
Sequence Stratigraphy and Sedimentological Model of Barúa Field Reservoirs, Eocene Misoa and Paují Formations, Lake Maracaibo, Venezuela
Authors: Escandón G. , Moreno M. , Chacartegui F
Published: December 2007

This paper presents the sedimentological and stratigraphical model for the Eocene section of Barúa Field, Maracaibo Basin, Venezuela (Fig 1). The main reservoir units are comprised at the base by the Upper Misoa sands (B-0/B-1) and at the top by the basal Paují sands (A-9/A-10).

The objective of this study was to establish and predict the geometry, distribution and physical reservoir quality of the flow units in order to implement a viable economic exploitation plan.

Hydrocarbon extraction in the Barúa field began in 1957 after the successful drilling of well MGB-1x. This field is producing 16 MB/D, and has so far reached a cumulative production of 83.3 MMB. The estimated OOIP is 1.4 MMMB and total remaining reserves are in the order of 226.7 MMB.
The Evolution of Horizontal Completion Techniques for the Gulf of Mexico: Where have we been and where are we going?
Authors: Foster Jeff , Grigsby Tommy , LaFontaine Jackie
Published: December 2007

Since the early 1990's, horizontal openhole screen completions have continued to gain acceptance as a viable completion technique for Gulf of Mexico high-permeability, soft-rock completions. The primary drivers for encouraging the use of this type completion have been the higher production rates that, when coupled with the increased percentage of recoverable reserves, have provided a quicker and greater return on investment (ROI) than other completion methods. Advances in directional and horizontal drilling, measurement-while-drilling (MWD), and fluid systems were the enabling technologies for drilling and completing of long openhole horizontal intervals. Because of the horizontal environment, specialized completion systems were required, developed, and successfully deployed. These systems have combined proven technology with new packer and service tool designs, production screens, etc. to adapt to the rigorous demands of the horizontal wellbore.

The viability of this completion technique is now being questioned as a result of the increasing number of completion failures. Some completions have experienced production rate declines, water coning, and/or sand production. Why has this problem suddenly become more pronounced?

This paper will discuss the chronological development of horizontal completion systems and the perceived drivers as well as the current innovations in completion tools and techniques. In addition, the speculation and causes related to horizontal completion failures will be addressed. Finally, the paper will discuss the completion trends of the future and attempt to answer the questions asked in the title by providing some possible resolutions to current horizontal completion problems.
Detection of Channel Sands and Vertical Shale Continuity Using a new Approach in Interference Analysis of Parallel Horizontal Wells
Authors: Alkhonifer J. , Ershaghi I.
Published: December 2007

This paper presents a new form of monitoring pressure interference data between two parallel horizontal wells for mapping reservoir permeability structure. The method is based on integrating the responses at multiple isolated probing points along a horizontal well path, and mapping permeability profiles from the application of a hybrid of deterministic and stochastic models.

Application to realistic system includes complex systems with channel sands embedded within an otherwise low permeability reservoir and discontinuous shale layers affecting vertical permeability.

The proposed method conceptually requires one or more pulsing points within the active horizontal well and a tool similar to an EFT moved along the responding well. Pressure responses from a series of interference tests, between two horizontal wells, are modeled to map the permeability distribution between the two wells.

The procedure has application in designing SAGD and other recovery processes in reservoirs where pairs of horizontal wells are planned for improved recovery. Information obtained, however, can further help in conditioning of geological models for other well configurations.
Layer Modeling for Cuttings Transport in Highly Inclined Wellbores
Authors: Kamp A. M. , Rivero M.
Published: December 2007

A review is presented on the state-of-the-art of mechanistic cuttings transport modeling. Cuttings transport predictions are essential for the planning of directional and horizontal drilling. It is suggested that field requirements (the need for fast, easy to use, simulators) point towards the use of a combination of two distinct modeling strategies, which are layer-models for the flow along the wellbore, and full numerical solutions in given cross-sectional areas. The layer model approach is developed in detail, yielding a two-layer model that simulates a moving bed of packed cuttings below a heterogeneous layer of mud and cuttings. Some key points on which more research is needed are highlighted.

The model has been used to perform numerical simulations, predicting cuttings bed heights, pressure drops, and transport velocities at different rate of penetrations and mudflow rates. Results have been compared to predictions by correlation-based models. The observed differences are discussed and improvements on the current model are proposed.
New Down-Hole External Casing Mud Removal Technology Improves Primary Cement Results
Authors: Dillenbeck Robert L. , Simpson Stewart
Published: December 2007

During the course of developing techniques and applications for better primary cementing results, it has become universally recognized that conventional drilling fluids and their residue must be removed from the annular space of a well before an effective hydraulic seal with cement can be achieved. To adequately protect well bore integrity, this hydraulic seal must be effective at both the cement to formation interface, and also at the cement to casing interface. To combat the problem of mud residue on the formation face, a vast array of external casing devices such as formation wipers and scratchers have been developed to help remove this residue through mechanical means. These devices, while effective at mechanically assisting chemical spacers and flushes in mud residue removal from the formation face, do nothing to help clean the exterior of the casing.

Due to its impermeable nature, casing suspended in a well is not subject to the same mud solids build up due to filtrate loss that exposed formations are. However, due to extremely low shear rates at the casing wall, some mud systems can build impressive gel strengths along the casing boundary, and become totally immobile. Experience has shown that this immobile layer can even resist the abrasive flow of cement slurries on the inside of casings, and resulted in the development of the bottom wiper plug commonly used to remove mud residue from inside the casing on many cement jobs pumped today. When this same immobile layer of mud adheres to the exterior of the casing through the placement of cement, the cement can have a very difficult time bonding to the casing and creating the necessary hydraulic seal.

The authors have tested a new mechanical device both under controlled test conditions and in the field, which allows drilling fluid residue to be mechanically removed from the casing exterior both before and during the actual placement of primary cement in the casing annulus. The paper will detail the development of the technology involved, initial testing, and actual field application of the new tools. The results of select field trials where the new devices were run side by side with other older technology will be presented to illustrate the comparative effectiveness of the new technology at achieving improved annular hydraulic seals.
Unique Polycrystalline Diamond Compact (PDC) Cutter Improves Drilling Efficiency
Authors: Wilmot Graham Mensa , Ramirez Javier
Published: December 2007

Advancements in Polycrystalline Diamond Compact (PDC) cutter technology1 have boosted the development and performance of PDC bits. In establishing their contributions to PDC bit performance, cutters have primarily been evaluated in terms of their resistances to impact and abrasion. Additionally, other characteristics such as interface strength, burst resistance, thermal stability and fatigue are also analyzed. Maximizing these properties improves cutter durability2, which subsequently enhances PDC bit performance and drilling efficiency.

Although desirable, the above objectives are not easily attainable. Most of the properties listed above exhibit inverse relationships, therefore maximizing any specific property has normally been achieved at the expense of the others. This caused the industry to focus on the development of technologies that optimize the performance characteristics of cutters3. These efforts have been beneficial, because improvements have been achieved in cutter durability. However, the need to keep extending the application envelopes of PDC bits requires continuous improvements to be made in cutter technology.

A newly developed cutter (NDC) is enhancing PDC bit performance. NDC has a unique geometry, which when applied to any cutter, regardless of size or substrate length, redefines the known relationships between WOB, RPM, Torque and ROP. The geometry, which is defined by the following parameters - offset, tangency, leading and trailing angles - has been stress engineered into NDC's tungsten carbide substrate. When applied to any PDC cutter with optimized performance characteristics, NDC's unique geometry helps establish new standards in PDC bit performance.

The paper will define a new set of performance qualifiers for PDC cutters. It will establish the relationships between NDC's parameters and the effect they have on the drilling operation. Additionally, it will ascertain how NDC's unique geometry enables achievement of the new performance qualifiers. Analytical and field support will be presented to show how NDC improves drilling efficiency.
Surface Axial Load Based Progressive Cavity Pump Optimization System
Authors: Mena L , Klein S.
Published: December 2007

Actual Field tests performed in heavy and extra-heavy oil wells in San Tome, Venezuela reveal that axial load does have a direct relation with Progressive Cavity Pump (PCP) downhole conditions. The differential pressure across the pump is easy to infer by just measuring the surface axial load of the system and surface pressures. This fact is particularly useful to diagnose a PCP (known to be very difficult to do for this system). Good inferences on downhole conditions allow PCP optimization to be done much easier and more efficiently. It has been proven in beam pump applications that the dynagraph chart (axial load vs. pump cycle) can be used to diagnose and optimize the pump and the well. The same principle is used for PCPs, except a rotational effect has to be taken into account. Of course by using the rest of the operational data that assist with construction and recognition of operational patterns, the PCP diagnostics becomes more exact and efficient for the production engineer.

The work herein presented reveals field tests of the system used to optimize PCP wells, based on the important usage of axial load and several other variables (current, pressures, etc) with a special ingredient that has a tremendous impact in optimization: Artificial Intelligence and Automation. The mathematical principles are also presented to encourage the usage of axial load in a multivariable mathematical model in order to complete a good optimization scheme for these wells. The hardware tools in the well completion needed to perform such a task are discussed as well, including the axial load measuring device.

The benefits of operating a PCP system using a Progressive Cavity Pump Optimization System (PCPOS) are substantial, as described in this paper. The idea is to reduce downtime, workovers, improve system operating response time and equipment useful life, while optimizing the well production.
Integrated Laboratory Field Application for Thermal Recovery Process
Authors: Lopez Elias , Rojas Luis , Mata Tomas , Mendoza Humberto , Briñez Abrahan
Published: December 2007

The Bolívar Coast Heavy Oil Fields (Tía Juana, Lagunillas and Bachaquero), located at the eastern onshore area of Maracaibo Lake, Western Venezuela, contain some 37 billion barrels of Oil Originally In Place. The recovery from these three giant fields is 5.5 billions (15% STOOIP), and is expected to reach 7.7 billions (21% STOOIP) under current primary recovery method (Cyclic Steam Injection).

It has been estimated that an additional 39% of STOOIP in potential areas for steamflooding could be recovered by this process. Previous conceptual studies, and field projects in Bolivar coast area has showed high recovery factor and marginal economics. Those project were conducted under conventional application of technology.

In the last 10 years, technology has evolved in such a way that monitoring can be improved and the performance enhanced for secondary recovery process. These new technologies, such as 4D seismic, Tomography, fiber optic, new approach for steam generation etc., have been tested in different steamflood projects with high impact in the added value.

PDVSA E&P has adopted a new approach to carry out technological projects under the philosophy of the Integrated Field Laboratories. This concept is a wider definition of a Pilot Test, since it encompasses the ideas of evaluating a secondary recovery process and performing the corresponding reservoir management.

The reservoir management includes the evaluation of different technologies for monitoring and control and the simulation and visualization of the process itself, so injected fluid fronts can be tracked down the reservoir. This will allow the creation of an integrated data base and the use of intelligent information systems in order to predict changes and perform decision analysis. The lesson Learned in this Lab will help us to optimize and become marginal projects into profitable ones.

This paper presented the results obtain up to date in the integrated field laboratory that for heavy oil is conducted in W-6 area of Lagunillas Field in the Bolivar coast.
Flow Simulation Study of the Namorado Sandstone (Albacora Field, offshore Brazil) Accounting for Scaling of Petrophysical Properties
Authors: Bonet L. , Romeu R. K. , Barroso A. S. , Sombra C. L. , Cortez M.M. M. , Almeida S. R. , Schwerdesky G. , Mihaguti M. K. , Sarzenski D.
Published: December 2007

This paper describes the reservoir flow simulation study of the Namorado Sandstone, Albacora Field (offshore Brazil). This study is the end point activity – to which the geological description, geostatistical modeling and upscaling results converge – of the project PRAVAP-2, a main project designed to develop technology on reservoir characterization at Petrobras. This paper details work executed by a multidisciplinary team on a flow simulation study performed in a stochastic modeling scenario. We present aspects related to the model construction and the results obtained from the flow simulation study.

The fluid flow model considers a deterministic framework built with high-resolution stratigraphy and detailed structural analysis. Twelve stratigraphic units were grouped in six simulation layers. The heterogeneities inside each layer were modeled using a geostatistical approach: we used the Markov-Bayes simulation method to integrate seismic and well data.

A multi-step upscaling technique was used to generate the effective petrophysical properties for the fluid flow simulation model. The idea is based on (1) a hierarchical description of the reservoir heterogeneities and on (2) the computation of the effective properties bottom-up through this hierarchy. Three main work scales were defined: "porous systems" (microscopic scale); "composite facies" (log and core scale); and "seismic facies" (interwell to field scale). Effective permeabilities and two-phase pseudo-functions were numerically computed for each facies at each scale.

The simulation grid has a corner point geometry, comprising a total of 46,200 gridblocks with areal dimensions of 100m x 100m. The interconnection of layers was modeled by changing the vertical transmissibility distribution.

The history matching was performed by the adjustment of the average pressure for the six layers and of the reservoir production history. The results demonstrated that our sophisticated model allowed a very fast history matching. Extrapolations investigated the adequacy of the development plan, in special the type of the well, horizontal or hydraulic fractured vertical, the number and locations of these development wells to be drilled.
Large Scale Integrated Reservoir Study: The Bachaquero Intercampos Experience
Authors: Lopez D. , Muñoz R. , Gonzalez J. E. , Gou Y. , Pascual J. C. , Cosentino L.
Published: December 2007

A large scale integrated study has been performed in the Bachaquero Intercampos Field, Lake Maracaibo, Venezuela. The project concentrated on the complete revision of the static and dynamic models of the field, with the aim of identifying new reserves and define a new development plan. The dimension of the field and the huge amount of available data required an effort in terms of prioritizing the technological and human resources allocated to each discipline.

The new geological model revealed the presence of a previously untargeted shadow zone below the main reverse fault of the field (subthrust trap). The development plan was focussed on the exploitation of these new reserves and is adding about 10 years of production to the field.

The first phase of the development plan started in early 1998 and so far 3 wells have been drilled and completed. These wells confirmed the new geological model and are currently producing more than 15% of the total field production.
Discounting Rate: A Matter of Common Sense Rather than a Theoretical Problem
Authors: Rosbaco Juan A.
Published: December 2007

Different rates proposed by several authors to discount cashflows of given projects are discussed. The paper starts by reviewing what the objectives of an evaluation are and later presents the different discount rates suggested by the authors. After a theoretical but fundamentally logical analysis it is concluded that there is no universal discount rate that can be used in all situations; to do so would disregard both the fact that an evaluation can have different objectives and that the environment in which projects will be carried out and companies will develop is unique in each case.
Determination and Prediction of Wax Deposition from Kuwaiti Crude Oils
Authors: Elsharkawy Adel M. , Al-Sahhaf Taher A. , Fahim Mohamed A. , Al-Zabbai Wafaa
Published: December 2007

Crude oils produced from the formations are transported and processed at low temperatures where solid wax particles may precipitate. These solid particles cause additional pressure drop in production tubing, pipeline, and processing equipment and eventually cause plugging. Great saving in the cost of operating such equipment can be achieved from accurate prediction of wax appearance temperature (WAT) and the amount of wax formed at given conditions.

This paper reports measurements of wax content by acetone precipitation techniques as well as measurements of wax appearance temperature (WAT) by viscosity measurements and differential scanning calorimetry (DSC) of eight different stock-tank Kuwaiti crudes. Viscosity measurements indicate that crude oils exhibit Newtonian behavior at temperature above WAT and Non-Newtonian elsewhere. Comparison of WAT measured by DSC and viscosity indicates that the viscosity method overestimates the WAT. Crude oil gravity measured, by digital density meter, and molecular weight, by vapor pressure osmometer, were used to characterize the plus fraction and predict WAT and amount of wax formed at given condition by the thermodynamic model. Comparison between predicted and measured results shows that measured Wax appearance temperature (WAT) by DSC compare very well with that predicted from the model for most crudes. However, Wax contents measured by modified UOP method 46-64 are not in good agreement with that predicted by the thermodynamic model.
Applications of Geomechanics in the Development of the Naturally Fractured Carbonates of the Mara Oeste Field, Venezuela
Authors: Sánchez D. M. A. , Vásquez A. R. , Van Alstine D. , Butterworth J. , García J. , Carmona R. , Poquioma W. , Ramones M.
Published: December 2007

A geomechanical study for naturally fractured carbonates was performed as part of an integrated study for the Mara Oeste field in Venezuela. The study included working with one paleomagnetically-oriented core in which natural and induced fractures were identified and oriented. Geomechanical static and dynamic laboratory tests were performed, to obtain strength, deformability and failure characteristics of the rocks. The in situ stress field orientation was determined in one well by using special core techniques such as ASR, DSA, AAA and SWAA. Regional information provided by focal mechanism data available in the Maracaibo basin was integrated together with image logs for eleven wells. Natural fractures and breakouts were studied and fracture orientation and in situ stresses were related with geological structures present in the field. A stress orientation map was built with all the available directional information. In situ stress magnitude was estimated by lost-circulation data, extended leakoff test and back-analysis from breakouts. A three-dimensional stress model of the field was performed using a lagrangian finite difference code. The model showed that stress orientation is dependent on geometry of the layers, and faulting can introduce jumps in stress magnitude. Out from the influence of the main faults the model reproduced the regional trend of stresses. Close to the main fault of Mara Oeste, stress rotation was evident both in depth and spatially, particularly at the crest of the folds. The model provided estimates of in situ stress magnitude that can be used to design new wells in blocks with little information.
Use of Surfactants in Cyclic Steam Injection in Bachaquero-01 Reservoir
Authors: Valera Cesar A. , Escobar Manuel A. , Iturbe Yrene J.
Published: December 2007

Bachaquero-01 is one of the biggest heavy oil reservoir (11. 5 °API, 23511 acres and 6621 MMBO of OOIP) that possesses Petroleos de Venezuela (PDVSA) western division in Maracaibo Lake Basin.

Cyclic steam injection as a development strategy in Bachaquero-01 began in 1971, and until November 1998 a total of 344 wells have been stimulated with 1006 cycles.

In Bachaquero-01 reservoir verticals wells are completed in one, two, three or four oil producing zones, in a range between 80 and more than 300 feet, as a consequence gravity override and steam channeling are two reasons that reduce the efficiency of production in cyclic steam injection. In order to reduce these mentioned effects, a surfactant of the linear ionic-alkyl-aryl sulfonate type (LAAS) has been used, which generates a stable foam that has as objective to block the most permeable areas and to achieve a uniform injection profile in order to stimulate efficiently those zones with low permeability and recovery. This effect has allowed obtaining between 15 and 40% more production per cycle.

This technology was evaluated in 1997 in the horizontal and reentry wells completed in the main sand of the reservoir, with the purpose of obtaining a uniform profile of injection along the whole horizontal section. The production obtained after the period of soaking indicates a very good stimulation in this type of wells, for that reason its use is being extending in 1998.

This paper presents the results obtained with the stimulation with steam and surfactant carried out to the vertical and horizontal (new and reentry) wells belonging to the Bachaquero-01 reservoir.
Recent Advances in Steamflood Technology
Authors: Hong K. C.
Published: December 2007

Worldwide heavy oil production has undergone phenomenal growth since the first known application of steam in the late 1950s. This growth, especially during the past decade, resulted primarily from technological advances made in the areas of steamflooding that include the process itself, steam generation and distribution, injection and production facilities, and performance prediction. These advances helped increase oil recovery, extend the process application to wider ranges of reservoirs and fluids, and improve the process efficiency (e.g., reduce operating costs). This paper describes some of the more important technological advances made during the past decade.
Fracture Growth and Reorientation in Steam Injection Wells
Authors: Weijers L. , Wright C. A. , Demetrius S. L. , Wang G. , Davis E. J. , Emanuele M. A. , Broussard J. B. , Golich G. M.
Published: December 2007

Conventional wisdom regarding fracture orientation1 of steam fractures is that they grow along the same orientation as "typical" propped fracture treatments – i.e., perpendicular to the least principle stress direction. However, direct measurements (utilizing surface tiltmeter fracture mapping) show that the orientation of steam-induced fractures is very different from propped fractures. Steam fractures have been observed to grow predominantly along two distinct planes that are oriented 45° with respect to the preferred fracture plane. These two planes coincide with the planes of maximum shear stress. Steam fracture reorientation toward these two planes has thus far been directly observed in the South Belridge, Lost Hills, and Cymric Fields in the San Joaquin Valley in California.

The measured data also shows that the fracture orientation is sensitive to the injection rate. Above a "critical" rate (which most likely depends on horizontal stress bias, shear frac conductivity and fluid viscosity) fractures grow perpendicular to the minimum principle stress. Below this critical rate, however, fracture growth is along the two distinct maximum-shear orientations. Steam injection wells are especially vulnerable, as steam injection rates are generally low in comparison to propped fracture treatments. The proposed mechanism for steam fracture reorientation that we present in this paper is pore pressure elevation along a direction of enhanced permeability along shear fractures ahead of the fracture tip, which causes the preferential fracture growth direction to change along the direction of maximum shear stress.

Although fracture reorientation can provide an increase in reservoir access and production rates in areas where the "huff and puff"-technique is used, reorientation is detrimental for steamfloods, as "short-circuiting" may result and reserves may be bypassed.
Softening of Produced Water: Which System is Best for your Application?
Authors: Mommaerts Guy J.
Published: December 2007

Softening of produced water with Ion Exchange Resins has been done for many years. This paper briefly reviews these systems and introduces some new ion exchange systems such as Packed-Bed applied to the softening of produced water. The impact of brine hardness is discussed describing the possible merits of using softened brine. These new techniques have lead to re-evaluating the selection of equipment, especially for water with a TDS of 4000 to 7000 ppm.
Pilot Study Results to Convert Oil Field Produced Water to Drinking Water or Reuse Quality
Authors: Doran Glenn F. , Williams Kimberly L. , Drago Joseph A. , Huang Sunny S. , Leong Lawrence Y.C.
Published: December 2007

The project goal is to convert a currently unusable by-product of oil production, produced water, into a valuable drinking water resource. Results from a 10 gpm pilot study were used for a conceptual design and cost estimate for a 44,000 bpd treatment facility. Generally, the pilot study demonstrated that by altering operating conditions, the treated water could meet industrial, irrigation, and drinking water quality standards. Four scenarios were evaluated, 2 industrial and one each for irrigation and drinking water. The total project cost estimates, with an accuracy of approximately −15 to +30 percent, ranged in capital cost from $3.1 to $12.3 million with an O&M cost ranging from 4.5-23.4 ¢/bbl of water treated.
The Application of Modular Formation Dynamics Tester -MDT* with a Dual Packer Module in Difficult Conditions in Indonesia
Authors: MP Siswantoro , Indra T. B. , Prasetyo I. A.
Published: December 2007

Since the introduction of the wireline formation tester in 1955, these tools have provided the oil and gas industry with measurements for the determination of formation pressure, fluids in-situ as well as giving formation fluid samples for identification and analysis.

Pressure and fluid samples are obtained by setting a rubber packer and small diameter probe. The packer hydraulically isolates a small part of the formation from the hydrostatic pressure, while the probe enables communication between the tool and formation. This conventional technique is well suited for thick and permeable clastic formations. However, for difficult conditions such as fractured limestone, thin and laminated formations or formations with very low permeability, the application of a single probe technique is limited. Under these conditions, the small packer may not be able to isolate the zone, may miss a thin zone or in a formation with very low permeability, the contact area with the packer may be too small to let the fluid flow. To identify formation fluids under any of these conditions, a cased hole DST was usually run, but this is time consuming and costly.

To help overcome this, a new technique has been developed using the MDT* with a dual packer module. Within Indonesia, this technique has been applied successfully to a fractured carbonate reservoir, a thinly-bedded reservoir and a formation with very low permeability. This wireline conveyed straddle packer has the capability of hydraulically isolating a minimum of one meter of formation. The dual packer can be set repeatedly at different locations on a single trip in the well. Using these, pressures, real-time formation fluid identification, PVT samples, permeability and flow rate estimations can all be evaluated in detail. Electrical borehole images (FMI*) have been incorporated into this technique to locate fractures and laminations in order to improve the choice of test point.

This paper describes the practical use of this technique in these types of very difficult formations that occur within Indonesia and demonstrates the benefits of this new technology.
Selection of Metallurgy and Elastomers Used in Completion Products to Achieve Predicted Product Integrity for the HP/HT Oil and Gas Fields of Indonesia
Authors: Williford James , Rice Pat , Ray Thomas
Published: December 2007

In the Indonesian Archipelago oil-and-gas fields, high pressure/high temperature (HP/HT) sour-service applications are becoming more prevalent as new areas are being explored and defined. In order to select the appropriate metallurgy and elastomers for completion products in these corrosive environments, careful consideration must be given to the well environment. Therefore, thorough review of well data is required so that completion cost efficiency can be realized, and product integrity can be maintained. This paper will present a selection process that can be used to identify the most appropriate metallurgy and elastomers for various wellbore environments, and in the case histories presented here, was beneficial in selecting the completion components for the HP/HT applications in these fields.
Operational Procedures and Applications of a Wireline Formation Tester to Accurately Characterise the Gas Composition of Stacked Multiple Pools in the North Malay Basin
Authors: Baxter Martin F. W. , Abdullah Zulkiflie , Pearson Michael R.
Published: December 2007

An accurate knowledge of reservoir fluid composition, specifically the concentration of hydrocarbon gases and non-combustible gases such as carbon dioxide, is a key factor in the commercial assessment of upstream gas projects at the exploration and field appraisal drilling stages, and in development planning.

The precise measurement of reservoir fluid composition requires the acquisition of a representative sample of formation fluid, free of drilling fluids and other contaminants. Traditionally, Drill Stem Tests have offered the most reliable method to obtain this information. However, the cost of this method limits its application in gas accumulations comprised of multiple, stacked, separate pools where the individual reservoir fluid compositions need to be well known.

Carigali Triton Operating Company Sdn. Bhd. (CTOC), Operator of Block A-18, JDA on behalf of its Shareholders, Petronas Carigali (JDA) Sdn. Bhd., Triton Oil Company of Thailand (JDA) Limited and Triton Oil Company of Thailand Inc., is now consistently able to acquire reservoir fluid samples which are confirmed by on-site advanced chromatography, and calibrated by Drill Stem Tests to be fully representative of in-situ native reservoir fluid compositions. This has been achieved through the use of a wireline formation tester with an enhanced pump-out capability and a downhole fluid analyser, together with the development and implementation of key operational procedures for performing the logging operation.

The accuracy and reliability of the technique has been proven and refined over the sixteen-well exploration program in Block A-18, where downhole conditions can be hostile, and tool operating time has exceeded 40 hours. This technique has enabled the Operator to obtain specific and accurate information on the fluid composition of individual reservoirs, and therefore reduce appraisal and development uncertainties, in a fraction of the time which would have been needed for conventional Drill Stem Testing, and at a fraction of the cost.

This paper describes the tool, together with the techniques that have been implemented at the well site to obtain representative reservoir fluid samples in an efficient and cost-effective manner. Wireline Formation Tester Drill Stem Test results from the Block A-18 exploration and appraisal program to date are compared to demonstrate the accuracy and reliability of the methods employed.
A Comprehensive Monograph for Hydraulic Fracture Initiation From Deviated Wellbores Under Arbitrary Stress Regimes
Authors: Hossain M. M. , Rahman M. K. , Rahman Sheik S
Published: December 2007

Hydraulic fracturing is a widely used stimulation technique in the petroleum industry for enhanced hydrocarbon recovery from low permeable reservoirs. Technological advancements in directional drilling have led the petroleum industry to drill arbitrarily deviated wellbores for development of reservoirs, which otherwise could not be economically produced. Efficient prediction of fracture initiation pressure from such deviated wellbores is therefore essential for petroleum industries to undertake effective hydraulic fracture stimulation tasks. This paper presents a generic model for prediction of hydraulic fracture initiation pressure and the orientation and location of fractures on the wellbore wall. The generic model is finally ramified to develop criteria for initiation of longitudinal, transverse and T-shaped or H-shaped fractures, with and without perforations. Final form of fracture initiation criteria for specified cases presented in the paper can be used by engineers for prediction of fracture initiation pressure. However, the estimation of fracture initiation pressure for deviated wellbores is cumbersome requiring numerical iterations. For such cases, results are presented graphically in terms of non-dimensional parameters to cover various stress regimes and wellbore deviations. Thus, the charts presented in this paper will be a useful tool for prediction of fracture initiation pressure for given in-situ stresses and help engineers to minimize computational efforts.

Results of this study suggest that horizontal wellbores under the normal faulting stress condition requires less pressure for fracture initiation compared to vertical wellbores. In general, there is an optimum deviation that requires minimum fracture initiation pressure for a given set of in-situ stresses. Longitudinal fractures usually initiate from wellbores which are aligned with one of the in-situ stresses. Under some specific stress conditions, transverse fractures may also initiate directly from the wellbore wall. Without appropriate pressure control, longitudinal fractures also, however, initiate at some elevated pressure during the propagation of transverse fractures. This introduces the so-called T-shaped or H-shaped fractures. Perforations at appropriate alignment usually contribute in fracture initiation at lowe pressure.
A Unique Method of Paraffin Control in Production Operations
Authors: Dobbs James B.
Published: December 2007

Paraffin deposition has long been a problem for many oil producing areas. The use of paraffin inhibitors, which are sometimes referred to as wax crystal modifiers or pour point depressants, have been effective at reducing problems caused by paraffin deposition. These materials must be applied at a point before the paraffin falls out of solution and they must be present on a continuous basis. This presentation describes a technique for squeezing inhibitor into the reservoir rock matrix to get a slow consist return of inhibitor that provides an extended treatment for controlling deposition.
The Experimental Studies of Physical Simulation of Bottom Water Reservoirs With Barrier and Permeable Interbed on Horizontal Well
Authors: Dou Hongen , Guan Changzhi , Lian Shengjiang
Published: December 2007

The paper presents the experimental study that is flow mechanism of bottom water breakthrough into oil well with horizontal well of barrier interbed and permeable interbed was studied, and reservoir physical simulations of barrier layer and permeable interbed flow of horizontal well were performed by 2D physical visible model. The model is made of two polymethylmethacrylucote planes of transparent and the metal frame that dimensional is 700mm × 300mm × 14mm. The production mechanism and flow behavior of bottom water reservoirs of barrier interbed and permeable interbed horizontal well was revealed. All development process of water cresting of barrier interbed and permeable interbed were shown by the experiment. Meanwhile, the some rules that are point displacement no better than the displacement of bottom water, and there is no phenomenal of water cresting to the permeable interbed, and result in water-free recovery percent of reserves and terminal oil recovery both are enhancement. The authors discovered that the weak permeable interbed had high water-free recovery percentage of reserves and terminal oil recovery after the weak permeable interbed compares with the barrier interbed. The experiment reveals the to effect horizontal well production rate on main sensitive factors, such as the horizontal well length and the displacement pressure drawdown. The paper presents also same horizontal well length to increase pressure drawdown about two times then terminal oil recovery to decline 3.14per cent and water-free recovery percentage of reserves to decline 13.7per cent to the weak permeable interbed. The bottom water reservoir of weak permeable interbed and barrier interbed both should develop to mitigate water cresting and prolong bottom water breakthrough into oil well in the some degrees respectively.

Using the multilateral well to build up manual barrier layer for the water control in bottom water reservoir with horizontal well. The new concept development has been established through the experiment.
Oil Recovery Potential From Fractured Reservoirs by Mass Transfer Processes
Authors: Stubos A. K. , Poulou S.
Published: December 2007

The purpose of this work is to evaluate the incremental oil recovery by evaporation and diffusion processes in fractured reservoirs and to provide a simple method for scale-up assessments. A macroscopic analysis of the flow and mass transfer phenomena in the porous matrix is performed on the basis of previously published experimental observations on core samples. This leads to analytical expressions for the evaporation, or, equivalently, drying rate, the extent of the two-phase zone in the matrix, and the location of the propagating front during both the steady and the falling rate periods of the process. Such expressions permit fast, albeit approximate, scaling considerations and recovery potential calculations. They also lead to conclusions concerning the optimal injection conditions and the desired injection gas properties.
Processing and Interpretation of Long-term Data from Permanent Downhole Pressure Gauges
Authors: Athichanagorn Suwat , Horne Roland N. , Kikani Jitendra
Published: December 2007

Long-term data from permanent gauges have the potential to provide more information about a reservoir than data from traditional pressure transient tests that last for a relatively small duration. Besides reducing ambiguity and uncertainties in the interpretation, long-term data also provide an insight on how reservoir properties may change as the reservoir is produced. This type of long-term surveillance provides the opportunity to look at the reservoir information in four dimensions rather than obtaining a glimpse or snapshot in time. However, the installation of permanent downhole gauges is only a recent phenomenon, and a methodology for the interpretation of the data has yet to be developed. The use of long-term data requires special handling and interpretation techniques due to the instability of in-situ permanent data acquisition systems, extremely large volume of data, incomplete flow rate history caused by unmeasured and uncertain rate changes, and dynamic changes in reservoir conditions and properties throughout the life of the reservoir.

This study developed a multistep procedure for the processing and interpretation of long-term pressure data. The procedure was tested with several sets of simulated and actual field data. It was found to be an effective approach for the analysis of long-term pressure data from permanent gauges.
Determining Depth-Dependent Reservoir Properties Using Integrated Data Analysis
Authors: Phan Vinh , Horne Roland N.
Published: December 2007

The ambition of modern reservoir modeling is to make integrated use of dynamic data from multiple sources to infer the reservoir properties. The process of inferring the reservoir properties from indirect measurement is an inverse or parameter estimation problem.

The parameters of interest in this work are porosity and absolute permeability. These parameters have important influence in determining the performance of the reservoir and in reservoir optimization. This work represents a way of estimating such parameters from a variety of indirect measurements such as well test data, long-term pressure and water-oil ratio history, and 4-D seismic information. The work also considers the effect of the data on the uncertainty and resolution of reservoir parameters. In particular, since earlier work has addressed two-dimensional problems, this study focuses on the estimation of parameters in three dimensions where properties vary as a function of depth.

The study determined that depth-dependent properties can be estimated to varying degrees of precision, depending on the resolution of the data used to constrain the model. Seismic data generally has poor depth resolution, hence it was found that parameter estimates are better determined areally.
Use of Experimental and Simulation Results for Estimating Critical and Optimum Water Injection Rates in Naturally Fractured Reservoirs
Authors: Putra E. , Fidra Y. , Schlechter D. S.
Published: December 2007

This paper describes the experimental and simulation studies to determine critical and optimum injection rates during waterflooding in the naturally fractured reservoirs of the Spraberry Trend Area. The experimental study was performed using artificially fractured cores at reservoir temperature (138°F) and 500 psia confining pressure.

Based on the experimental results, an equation to determine the critical water injection rate (maximum injection rate at which the capillary imbibition is not effective) was developed to scale up laboratory results to field dimensions. We found that capillary imbibition transfer is not only a function of matrix permeability and maximum matrix capillary pressure but also a function of other matrix properties, such as wettability, porosity, matrix area and water viscosity. Two field cases using this scale-up equation are presented.

The optimum injection rate (the injection rate at which the capillary imbibition and viscous forces are balanced) for different well configurations cannot be determined from laboratory experiments; therefore, a reservoir simulation was employed. A 40-acre pilot was developed by utilizing a commercial dual-porosity simulator. Three different injection schemes were applied for four vertical and two horizontal injection wells, with constant injection rate and two different cyclic injection rate schemes. The numerical results show that four vertical injection wells at the optimum injection rate could yield higher oil production than two horizontal injection wells at the optimum injection rate. Use of a cyclic injection rate could restore reservoir pressure and increase oil recovery in the Spraberry Trend Area. The findings of this study could be useful to solve the problem of early water breakthrough, one of common problems of waterflooding in all naturally fractured reservoirs.
Development of a New Fiber-Optic-Based Offshore Structural Monitoring System
Authors: Guaita Paolo
Published: December 2007

The paper focuses on a new structural monitoring system based on the use of fiber optic strain sensors. This system has been developed and tested at sea on a full scale experimental riser in the frame of an R&D project fully funded by ENI/Agip division. The system is based on the measurement of longitudinal deformation of optical fibers via interferometric techniques. No active device is located underwater while all the system's complexity is grouped and packaged in a conventional electronic rack.

The test at sea of such a system is, to our knowledge, a world first not only for the oil industry.

The activities that led to the development and full scale test of the new Fiber optic based system (research objectives, Feasibility study, laboratory experiments, full scale test description, test results) are described.

Description of the main features of the new system and comparison with conventional electronic systems is provided