bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rigless Techniques Enhance the Effectiveness and Economics of Water Shut-Off
Authors: Farooqui M.A.S.Z. , Al-Rufaie Y.A. 
Published: December 2007

Abstract
This paper reviews the effectiveness of three rigless techniques to reduce water production from oil wells that either produce excessive amount of water or become unproductible due to high water cut. Two techniques, setting a through-tubing bridge plug and plugging the water producing section with a cement plug have become standard procedures while the third technique, which involves pumping a polymer gel system in the reservoir, is still under testing and evaluation to determine its suitability in Saudi Arabian reservoirs. During the last two years, 42 water shut-off jobs were performed of which 35 jobs (83%) were successful in reducing water and increasing the oil production. Post-job water cut trends show that these jobs extend the productive life of the well by 1–2 years and have excellent payout prospects in terms of increased revenues from higher oil production and reducing water production, thereby reducing the associated water processing costs. From reservoir management point of view, these jobs help in maximizing recovery from areas of the reservoir that have been invaded by the advancing flood front.
P. 135
Challenges to Secondary and Tertiary Recovery Operations in Carbonate Reservoirs:
Authors: Lindsay R.F. 
Published: December 2007

Abstract
Carbonate reservoirs are inherently heterogeneous and challenging to secondary and tertiary recovery, due to:the depositional environment;the diagenesis that modified the sediment/rock;the nature of the enclosing trap; andthe properties of the fluids and gases that filled the reservoir.
Utilizing the above criteria when characterizing and managing carbonate reservoirs, from discovery to abandonment. gives an operating company opportunities to recover additional mobile oil (Fig. 1).
P. 173
A Development Project Case Study of the Virden-Daly Fields: Manitoba, Canada
Authors: Grant B.D. , Skow L.A. , Taylor W.J. 
Published: December 2007

Abstract
Virden and Daly are giant fields with mature waterfloods that have received minimal development attention since the waterfloods were initiated more than 30 years ago. An evaluation of the wells' production symptoms suggested that many areas within the fields were not optimized. Some areas display long, harmonic production declines with large remaining reserves. Other areas display injected water cycling through layers of high permeability while still other areas display a strong bottom-water drive that resulted in water coning. This paper describes a low-cost. short cycle-time method in which these fields were modeled and tested. A development pilot project was initiated to determine the economic viability of optimizing these fields. A conscious decision was made to accept a higher risk, but save time and money by designing a development pilot program directly from a conceptual. Streamtube displacement reservoir simulation. The 1996 pilot program consisted of 6 horizontal wells and 3 producer to injector conversions in areas of slow waterflood response, and in areas of water-cycling 3 polymer workovers on injectors were done to redirect water. Results suggested that the pilot program was an economic success. resulting in an expanded program for 1997 (9 horizontal wells, 5 conversions, and 1 polymer workover).
P. 177
Theory and Analysis Method of Pulse Testing for Responding Well in Buildup
Authors: Huang Bingguang , Li Shunchu , Liu Shuzhi , Zhai Huihai , Gan Zhenwei , Ma Hongmei 
Published: December 2007

Abstract
Pulse testing is an excellent technique used to determine the value and direction of reservoir permeability and other important parameters. When reservoir permeability is very low, however, the testing time that is designed by the conventional pulse testing theory may be more than two months. Its cause is that the pressure in many oil wells is still increasing when they have been shut in for more than thirty days. In view of the fact mentioned above, the authors developed a new theory and give interpretation method of pulse testing. The theory and method are suitable for responding well in buildup. In contrast, the conventional pulse testing theory is based on the fact that the pressure in the responding well must be stable. Consequently, it demands a much longer testing time than the new theory by the authors.
In the paper, a mathematical model is first established to describe the new pulse testing theory. with the wellbore storage coefficients and skin factors considered both in the responding well and in the pulsing well. Then, an exact solution to the mathematical model is derived in Laplace Space. According to non-linear regression analysis technique, the characteristic parameters of a reservoir are obtained by solving the objective function that is established by observed and calculated pressure. The theory has been applied to Shanshan reservoir pulse testing design and analysis for several times, the interpretation results are satisfactory, and the testing time is only 12 to 18 days in such reservoirs with low permeability as Shanshan. The actual application has shown that the new pulse testing theory and analysis method are practical. They can shorten the testing time, especially for low permeability reservoirs.
P. 217
Time Lapse Borax Logging in a Karstified Limestone Formation of the Panna Field,
Authors: Das Subhas C. , Fox Glenn A. , Zebrowitz Mark J. 
Published: December 2007

Abstract
Migration of undesirable fluids through cement channels behind the casing is frequently a cause of well productivity impairment. However, reliable identification of cement channels is difficult and, quite often, secondary cement squeeze jobs fail due to incorrect diagnosis of the existence, nature and extent of the channeling problem. Different techniques such as temperature profiling, radioactive tracer logging and activated water logging have been practiced in the industry, but the results are more often than not inconclusive. Borax logging has been used as an alternative method for detection of cement channels in sandstone reservoirs. The same technique has been applied in the limestone formation of the Panna Field located Bombay Offshore, India. The logging results are less definitive than for typical sandstone applications. However, with a proper understanding of the geological model, this detection technique can be effectively utilized as a cement channel identification tool.
P. 367
Use of New Horizontal Grids in Reservoir Simulation Models Improves the Chance of Success in Developing Marginal Thin Oil Rim Reservoirs using Horizontal Wells
Authors: Hsiu-Hsyong Hsu 
Published: December 2007

Abstract
This paper proposes an accurate method to represent horizontal wells in a reservoir simulation model. Conventionally, the model grids in the z-dimension coincide with the geological layers in order to honor the layer properties, resulting in non-horizontal corner point geometry grids. It is difficult to accurately place a horizontal well in this type of grids. At best it can be approximated by zigzagged segments within the model grids. This may create a serious problem in evaluating the application of horizontal wells in thin oil rims (35-65 feet). In this situation, the gas and water coning behaviors greatly affect the effectiveness of a horizontal well. A simulation model using zigzagged segments to represent a horizontal well often gives an un-reliable prediction because some segments may be misplaced toward the gas-oil contact while others toward the oil-water contact. This problem may become more acute in the assessment of a marginal field development where the expected productivity of a horizontal well may influence the economic outcome of the project. Therefore, a computer program has been written to "horizontalize" the z-grids while preserving the original reservoir volumes and permeabilities. Where there is a shale layer in the reservoir, the horizontal grids are adjusted such that the shape and location of the shale layer are precisely preserved. This is an important feature of the program in that the shale layer maintains its role as a barrier to the fluid flow. In this grid structure, non-neighbor connections of the model grids may occur; however, this can be handled by the reservoir simulator in use. The horizontal grids offer a number of advantages. First, a horizontal well can be accurately placed in the simulation model. Second, the optimal vertical position of a horizontal well in the oil rim can be meaningfully investigated. Third, the oil, gas and water rate profiles along the horizontal wellbore (from heel to toe) can be accurately predicted. This information is useful in the well completion design and in the planning of any flow control measures. This paper will present a benchmark study to illustrate the benefits of the horizontal grids and an application of these grids to the successful development of a UK North Sea field consisting of thin oil rim reservoirs.
Tracking Waterflood-Front Movement Using Production Logging and Cross-Correlating
Authors: Verma S.C. , Madhavan S. , Roy M.M. , Banerji S. 
Published: December 2007

Abstract
For many stratified limestone reservoirs, waterflooding through strategically placed injectors is a sound strategy for both pressure maintenance and increasing hydrocarbon recovery. Complications like heterogeneity, preferential depletion of layers and non-availability of suitable injector slots make this task difficult, and often leads to early and unexpected injection water breakthrough in some producers.
This paper basically deals with a part of the Bombay High field, with characteristics similar to the one described above. Production log interpretation was carried out on all the relevant injection and production wells in this area, and an attempt was made to understand the complex nature of the flood front movement at different points of time for individual layers. From the available log and core data on porosity and permeability in these distinct layers, a study was conducted to see if any cross-correlation can be made between the flood front movement and the reservoir parameters. Finally, the paper comments on whether such log and core deduced permeability data, which account for only a tiny fraction of the reservoir volume, is sufficient to predict water movement in other areas of the reservoir, based on data from surface testings and production logs.
P. 475
A Reservoir Management Case Study of the Nahorkatiya Oilfield
Authors: Khataniar S.K. , Bora A. , Borah N.M. 
Published: December 2007

Abstract
The Nahorkatiya oilfield had an initial stock tank oil in place of about 200 MMm and has been on production since 1953. The field is a structural-stratigraphic trap formed by block faulting resulting in a number of individual reservoir blocks of various sizes. The reservoir crude is saturated and combination drive with varying degree of aquifer support has been the primary drive mechanism. Pressure maintenance by gas and water injection and limited water/polymer flooding have been in operation in the major blocks. Overall field recovery is 31%, although in a few blocks recovery as high as 46% has been achieved through secondary recovery measures. This paper presents the reservoir management strategies undertaken at various stages of development to optimize production profiles and ultimate recovery.
P. 569
Identification of Coal Cleats/Fractures Using 2D and 3D Imaging Computed
Authors: Kumar Rajesh , Rundwal V.C. , Das T.K. 
Published: December 2007

Abstract
This paper presents a comprehensive X-ray computed tomography (CT scan) study on coal samples recovered from different layers of a coal deposit in an R & D well drilled in the central-eastern part of India. The cleats and fractures in the coal seams have been identified using 2D and 3D CT images.
The cleats / fractures present in the coal scam have been categorized based on the variation in the type of material or fluid filling the cleatsl fractures. On the basis of the results of CT scan and gas content analysis, it has been possible to select layers for a suitable stimulation job like hydrofracturing, to produce methane gas. Effect of acid treatment on the material filling the cleats has also been studied using CT scan technique.
P. 597
High Pressure/High Temperature (HP/HT) Seals for Oil and Gas Production
Authors: Ray Thomas W. 
Published: December 2007

Abstract
The drilling and completion of wells between 15,000 and 20,000 feet vertical depth has been actively pursued since the early 1950's because of the increased production capacities associated with these deeper wells. The high temperatures and high pressures inherent to this type environment, however, require special equipment to withstand the demands of the severe conditions to which the equipment will be subjected.
Selecting seals or sealing systems for oil and gas production necessitates a comprehensive knowledge of the chemistry of both the seal material(s) and the conditions of the environment in which the seals will be used. Understanding the unique characteristics of viscoelastic response is the key to understanding elastomers in general and applying them to specific uses.
This paper will discuss elastomer usage as sealing media in the oilfield; specifically, the use of polymeric seal materials will be followed from their usage in the oilfield from 1977 to the present and their evolution to the elastometric element packages that have been developed for today's needs in traditional as well as in severe service and high pressure/high temperature (HP/HT) applications. Of particular interest will be testing to which the newly developed seal element packages have been subjected, including the testing that was conducted in a deep well simulator.
Case histories will support the enhanced capabilities of the new generation of polymeric seal assemblies.
In addition to the new generation of elastometric sealing packages, composite sealing materials have also been developed for certain applications in which elastomeric materials have not been able to provide long-term integrity. Progress being made in this area will also be discussed.
P. 603
Injectivity Decline in Wells with Nonuniform Perforation Properties
Authors: Hofsaess T. , Kleintz W. 
Published: December 2007

Abstract
Nonuniform perforation properties and permeability variations close to the wellbore introduce heterogeneities which affect the injectivity decline in water injection wells. We present a method to calculate these effects and derive results for a simple model which incorporates the dependence of the water- quality-ratio on the entrance porewidths. Common degrees of heterogeneity may lead to significant changes in the injectivity decline, which cannot be described by conventional models of uniform wells. Early damage rates may be orders of magnitude larger than expected and wells with large initial skins are prone to having their half-lifes within this early region. Due to the resulting nonlinearities, extrapolations from test-injections may lead to wrong conclusions and it is usually not possible to predict the half-life by the conventional use of a single value for the water-quality-ratio.
P. 631
Field Application of Gelling Polymers in Saudi Arabia
Authors: Nasr-El-Din H.A. , Bitar G.E. , Bou-Khamsin F.I. , Al-Mulhim A.K. , Hsu J. 
Published: December 2007

H.A. Nasr-El-Din, SPE, G.E. Bitar, SPE, F.I. Bou-Khamsin, A.K. Al-Mulhim, SPE and J. Hsu, SPE, Saudi Arabian Oil company (Saudi Aramco)

Abstract
High water production causes major economic and operational problems for several reasons. It decreases oil production, and results in large amounts of produced water that need to be disposed. It also requires increased capacity of water separation and handling facilities. Other production related problems include high corrosion rates and increased tendency for emulsion and scale formation. Therefore, there is a need to reduce water production. Several mechanical and chemical methods are available for water shut-off treatment. However, the choice of a specific treatment depends on the source of water, well characteristics, and cost.
Water shutoff treatments using chemical means include injection of a gelling solution that forms a gel at reservoir conditions. Three main gelling systems are available to conduct water shutoff treatments: a water-soluble polymer with a cross-linker, phenol-formaldehyde resin, and sodium silicate gels. Based on extensive lab studies, two gelling systems were field tested in Saudi Arabia during the last few years. Both gelling systems were applied in a carbonate reservoir. The reservoir temperature is 220-240 F and formation water has total dissolved solids ranging from 45,000 to 200,000 mg/l. The first gelling system consisted of a polyacrylamide polymer, acetate and a retarder. This system was applied in two wells as a means to reduce water production due to coning and bottom water. The second gelling system consisted of sodium silicate with intemal and extemal activators. This system was applied in a well with a high permeability streak.
Several operational and quality control problems were encountered during and after field applications. This paper discusses these problems in detail and recommends modifications to these systems to avoid operational problems encountered in the field. Advantages and disadvantages of using several gelling systems are also highlighted.
P. 133
Polymer/rock Interactions in Polymer Treatments for Water-cut Control
Authors: Chiappa Luisa , Mennella Aniello , Burrafato Giovanni 
Published: December 2007

Abstract
In this paper we study the adsorption of polymers bearing differently charged groups onto solid surfaces of siliceous nature. By means of static adsorption tests we show that the adsorption is dominated by the electrostatic interactions between the polymer molecules and the solid surface. We also show that both lithology and brine composition can strongly influence the adsorption behavior; such effects must be therefore carefully assessed before applying these treatments in the field.
P. 161
Using an Analytical Decline Model to Characterize Naturally Fractured Reservoirs
Authors: Baker R.O. , Spenceley N.K. , Guo B. 
Published: December 2007

Abstract
Effective fracture spacing is critical to the design of waterfloods and CO2 floods in naturally fractured reservoirs. Decline rate data with imbibition data can be simply combined to estimate effective fracture spacing. This paper describes how carefully designed laboratory imbibition experiments were scaled to the field and how these simple observations were used to estimate fracture spacing for a large naturally fractured reservoir. Fracture spacing was also independently estimated by horizontal well cores. There was excellent agreement between the decline rate / imbibition spacing calculations and that obtained from the horizontal well cores.
P. 205
Experimental Investigation of Scaling Factors that Describe Miscible Floods in Layered
Authors: Peters Bradley M. , Zhou Dengen , Blunt Martin J. 
Published: December 2007

Abstract
We performed miscible flooding experiments in a layered model. The model was composed of glass beads, with two horizontal layers constructed from beads of different sizes. The miscible fluids used were water and brine. We conducted experiments in two models: a long model and a short model. One fluid was dyed and injected at different flow rates. Production profiles were monitored by weighing the effluent. Pictures of the displacement process were recorded on video camera.
We studied how recovery was affected by the gravity number, which quantifies the ratio of gravity to viscous effects on the displacement process. The behavior was investigated as a function of two gravity numbers: Ng, which is a ratio of the vertical buoyancy force to the horizontal viscous force; and Ng* which is the ratio of the time taken for fluid to move horizontally under viscous forces to the time taken to move vertically under buoyancy forces.
We show that when viscous and gravity forces compete (such as injecting less dense fluid into a system where the lower permeability layer is on top), recovery improves with increasing gravity number (Ng or Ng*), even in the regime where gravity would dominate in a homogeneous system. Gravity can thus be used to improve sweep efficiency in heterogeneous media.
By comparing our results from the long and short models we arrive at the following surprising conclusion regarding the two gravity numbers: for unfavorable mobility floods (injecting a less viscous fluid) Ng* best describes recovery, whereas for favorable mobility floods Ng best characterizes the behavior. An explanation based on the pressure distribution in a layered system is proposed.
P. 211
Two-Phase Flow Property Modifications by Polymer Adsorption
Authors: Zaitoun A. , Bertin H. , Lasseux D. 
Published: December 2007

Abstract
The ability for polymers or weak gels to reduce selectively the relative permeability to water with respect to the relative permeability to oil or to gas is a unique property well documented but poorly understood. To better understand two- phase flow property changes induced by polymer adsorption, an original experimental set-up was designed that enabled profile saturation check inside the core by gamma rays, material balance, pressure drop and direct measurement of the capillary pressure during displacement of oil by water. Relative permeability curves were computed with the measured data as input into a specially designed software (FISOLE).
Experiments were run first with a naturally water-wet sandstone (Vosges sandstone), then with the same type of core previously treated with silane to make it oil-wet. Main results obtained after polyacrylamide adsorption are:Disproportionate relative permeability modification is observed both in water-wet and in oil-wet cores.The polymer induces an increase in water irreducible saturation.The polymer induces an increase in the capillary pressure.After adsorption in the oil-wet core, the core becomes water-wet as attested by the inversion of the capillary pressure sign and the strong reduction in residual oil saturation.
All these results can be interpreted in terms of "wall effects", i.e. an adsorbed polymer layer of significant thickness is formed on pore walls. Comprehensive pictures of end point pore situations are provided.
P. 285
Pore-scale Mechanism for Selective Permeability Reduction by Polymer Injection
Authors: Mennella Aniello , Chiappa Luisa , Bryant Steven L. , Burrafato Giovanni 
Published: December 2007

Abstract
In this paper we discuss a pore-scale picture of the mechanism underlying the selective permeability reduction caused by the adsorption of a polymer layer in a water wet porous medium. Our analysis is based on the use of physically representative model of the porous medium, which allows us to estimate directly the expected permeability reduction. Comparison of model predictions with coreflood experimental data has revealed that the selectivity in permeability reduction cannot be explained if the polymer layer is modeled as a rigid, impenetrable layer. This result is consistent with the suggestion that swelling-shrinking phenomena of the adsorbed polymer later is responsible for the selectivity in the permeability modification induced by these treatments.
P. 323