bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Geological Volume Computer Modeling System for Reservoir Description
Authors: Swanson D. C.
Published: December 2007

A new geological three-dimensional computer modeling system has been developed that should greatly aid any task that depends upon accurate geological reservoir description. The new system, call STRATAMODEL, is a Geo-Cellular™ type of geological modeling that portrays the stratigraphic patterns and structural complexities of sedimentary rocks so that a resulting model closely approximates the "state of nature". Geologic volumes of any scale are divided into stratigraphic sequences and structural blocks. Into these are placed layers of cells which are positioned to be approximately parallel to the depositional surfaces or time-lines of strata being modeled. This results in the cell layers usually being at attitudes other than horizontal. Values and attributes are distributed from wells and assigned to individual cells within each unique cell layer. The resulting variation along cell layers is closely analagous to the variation of rock properties along strata in nature.

There are many potential benefits from using three-dimensional computer modeling. For example, in many reservoirs, the benefit of costly and detailed data is lost because of excessive vertical averaging. The use of accurate Geo-Cellular™ modeling will properly distribute parameters such as porosity and saturation. Pore volume can then be calculated at the individual cell level. This will lead to volumetrics more accurate than those determined by present conventional methods. Having a computer reservoir model will also allow the engineer and geologist the luxury of using alternate interpretations and multiple hypotheses.

The proper use of geological three-dimensional computer modeling system should greatly improve geological reservoir description and therefore lead to: 1) more productive infill drilling and recompletion programs, 2) more accurate deliverability and reserve determinations, 3) more efficient reservoir maintenance and surveillance, 4) more accurate reservoir simulation modeling, and 5) better enhanced recovery planning.
Design Optimization of Plunger Lift Systems
Authors: Avery D. J. , Evans R. D.
Published: December 2007

A general dynamic plunger lift model is presented which can be used to predict optimum design of a plunger lift system for wells which are producing by any reservoir mechanism. The upstroke and downstroke plunger models are coupled to a generalized inflow performance relationship thereby matching the production capability of the reservoir to the plunger dynamics. By matching reservoir performance and plunger dynamics the optimum slug size and cycle time can be determined which will maximize the liquid production for a given well.

A discussion of the development of the dynamic plunger lift model is presented and performance comparisons are made with other models available in the literature.

Conclusions are stated and potential improvements addressed concerning future work in plunger lift technology.
Computer Modeling and Optimization for Submersible Pump Lifted Wells
Authors: Lee H. K.
Published: December 2007

A computer simulation procedure is presented for evaluation and design of an electrical submersible pump (ESP). The System Nodal Analysis technique is also presented for modeling ESP lifted wells. The pump performance can be analyzed using the System Nodal Analysis technique by examining the well production rate versus wellhead back pressure, percentage of water cut and different motor speed as monitored by the Variable Speed Controller. The final goal of the computer simulation is to optimize the well production. Examples will be presented to illustrate the optimization procedure.
Coiled Tubing Non-Rig Workovers at Prudhoe Bay
Authors: Cobb D. O. , Bragg J. A. , Haines J. R. , Putnam J. S.
Published: December 2007

Arctic rig workover operations to perform reservoir control and remedial cement squeezes have been replaced by cost effective, state of the art coiled tubing technology at Prudhoe Bay. This non-rig workover (NRWO) approach is used to reduce high GOR and high watercut production without spotting a kill pill, pulling production tubing or drilling cement. The technique was implemented in the Prudhoe Bay Unit (PBU) Western Operating Area (WOA) during September, 1985, and includes 99 NRWO squeezes completed through December, 1987, by Standard Alaska Production Company (SAPC). This paper reviews the Production Operations and Engineering developments responsible for a successful NRWO program that has aided in extending plateau oil production and deferring decline point.

The Production Operations sections of the paper review field procedures and equipment used to perform low pressure squeeze techniques with low fluid loss cement slurries in an arctic environment. Discussion of field procedures include: cement slurry testing, pre-squeeze acid wash, sump cleanout, pressure control, wellbore liquid packing, Coiled Tubing Unit (CTU) depth control, pumping cement through coiled tubing and contaminating excess cement in the production liner to allow wellbore cleanout without drilling operations.

The Production Engineering sections of the paper review the candidate selection and evaluation process, general design considerations, program benefits and production results of WOA non-rig workover operations. As of year-end 1987, 57 gas shut-off (GSO), 23 water shut-off (WSO), 2 GS0/WS0 combination, 6 profile control, 2 plug & abandon and 9 pre-rig workover squeeze jobs have been completed. Program costs, incremental oil rate, additional recovery and repair longevity are also discussed.
Successful Application of Drilling Technology Extends EMPI’s Directional Capacity
Authors: Schroeter D. R. , Wah C. H.
Published: December 2007

This paper summarizes recent drilling performance on EPM’s Tabu, Palas, and Guntong platforms where a top-drive drilling system, PDC bits, MWD equipment, and low-toxicity oil base mud have been used to drill EPM’s deepest directional wells. These wells are as deep as 3750 meters (measured depth) with hole angles up to 73 degrees. More than two thirds of the wells are dual completions, each with two to three directional targets. The paper describes how this technology was used to overcome the usual problems in wells of this type, especially high torque and stuck pipe.
How Successful Acid-Frac Program Could Require Drastic Changes in Both Drilling and Completion Design
Authors: Despax D. , Bladier C. , Charlez P.
Published: December 2007

This article is based on five years experience in acid fracturing on a Middle East offshore field operated by TOTAL-CFP.

The field in question is a highly stratified formation containing dolomitic reservoirs which are separated by very compact and almost impermeable anhydritic interbeds. [FIG. 1]

The producing layers (A, B, C, D and E) vary in thickness and two of these are of particular interest: «A», which has already been considerably depleted with a fairly high matrix permeability (150 to 200 mD) and «E» only slightly depleted, and with a much lower matrix permeability (25 to 30 mD).
Estimating Rock Properties by Statistical Methods
Authors: Rodriguez E. , Tetzlaff D. M. , Mezzatesta A. , Frost E.
Published: December 2007

A statistical method for estimating rock properties from well logs has been developed and implemented in two computer programs: OPTIMA and OPTIMA-RT. Both programs use the set of available logs to estimate best values and confidence intervals of rock properties.

These programs are based on a non-linear weighted least-squares method, which combines actual measurements, theoretical values, and uncertainties into an objective function whose minimum yields the most probable set of results. The OPTIMA-RT program utilizes resistivity logs from devices having different depths of investigation to estimate diameter of invasion (d { ) and true resistivities of the virgin (R t ) and flushed (R xo ) zones. The OPTIMA package combines different types of log data to estimate porosity, fluid saturations, and mineral volumes.

We have applied the OPTIMA and OPTIMA-RT programs to a well located in the northern North Sea. Acoustic, radioactivity, and resistivity logs covering a depth of about 1000 ft were available for the study. Geologic information from the area indicates the presence of feldspar-bearing sands, silts, clays, mica, and other accessory minerals.

Resistivities calculated with the OPTIMA-RT program are used as input for OPTIMA. In spite of the lithologic complexity, mineral compositions calculated by OPTIMA agree with available geologic data. Variations in the confidence interval of the calculated values emphasize the importance of being able to measure the reliability of the estimation.
Stratigraphie Correlation of Well Logs Using Relational Tree Representation
Authors: Tsay F. S. , Lai P. F.
Published: December 2007

A new method of well log stratigraphie correlation is being described. The method is based on a heuristic waveform correlation scheme uisng relational tree data structure. The relational tree is used to provide a complete description of the contexture relationaships of the waveforms and a distance measuring process incorporated with a cross-over and multiple- links elimination procedure is impletmented to optimize the waveform correlation. Results have shown that the method is capable of handling the thickening, thinning and the missing strata which normally occur in stratigraphie correlation using well log data.
The Effects of Vertical Fractures on Areal Sweep Efficiency in Adverse Mobility Ratio Floods
Authors: Bargas C. L. , Yanosik J. L.
Published: December 2007

The industry has recognized for many years that the creation of hydraulic fractures is an excellent means of improving well productivity and injectivity. These induced fractures, however, can have a significant impact on sweep efficiency. This paper presents the results of a simulation study using a finite element model to determine the effects of hydraulic fractures on the areal sweep efficiency of contact miscible displacements in five-spot and line-drive patterns. The influence of fracture orientation, length, and conductivity for mobility ratios ranging from one to ten is reported for patterns where either the producer or injector, or both the producer and injector are fracture stimulated.

For favorably oriented fractures, the relative amount of improvement in areal sweep efficiency increases as the mobility ratio increases. Long highly conductive fractures at both the injector and producer are required to improve sweep for a five-spot pattern. Areal sweep in a line-drive pattern is more sensitive to fractures and can be improved by stimulating either or both wells. The greatest improvement occurs when both the injector and producer are fractured, while the smallest improvement occurs when only the producer is stimulated. Low conductivity fractures should be avoided because they can severely restrict the sweep improvement resulting from favorably oriented fractures.

Care must be taken to ensure that fractures are oriented in a favorable direction, however, because a significant reduction in areal sweep efficiency occurs if the fractures are oriented in an unfavorable direction. Since fracture orientation is not always known or cannot always be controlled, this study also identifies which length fractures prevent detrimental effects to sweep for unit and adverse mobility ratio floods with unknown fracture orientation.
Knowledge-Based Well Data Management and Graphical Interface
Authors: Citerne A. , Yu K.
Published: December 2007

Well log data including information about the wells from which the data was acquired, the tools by which the data was obtained, and the operations that were performed on this data, are best represented taxonomically by objects in a knowledge base for property inheritance. However, there are important non-taxonomical links between those objects. To be applicable, information must be presented and used according to different classification principles (philogenetic, phenetic, and teleologic).

The Graphic Log Data Manager (GLDM) is a graphical application that is designed to display these objects in a phylogenetic tree on a log analyst’s terminal. This tree can be adjusted (purged, annexed, etc.) to focus on only those data objects that a user wishes to examine. Furthermore, the GLDM uses different (but generic) trees, menus, tables, piano charts, curves, and the like to allow a log analyst to browse and edit the well data knowledge base and view, the log data in a desired structure during computer log analysis. Data access in the GLDM combines a frame-based, object-oriented facility and a declarative, adaptable non-taxonomical scheme. The purpose of the GLDM is, ultimately, to provide any log interpretation program with a visually flexible and adaptable data environment for log analysis.

The implementation of the GLDM depends not only on a comprehensive understanding of well log data, but also on a sophisticated information layout scheme and a comprehensive set of human interface tools.

It turns out that the artificial intelligence workstation programming environment and frame-based knowledge representation are appropriate and powerful vehicles to accomplish this.
Water-Base Mud System Having Most of the Advantages of Any Oil-Base System Plus Ecological Advantages
Authors: Carney L. L. , Güven N. , Panfil D. S.
Published: December 2007

A medium pH range water base mud system designed as a result of high temperature high pressure studies on various clays and polymers has been laboratory developed and field tested. This type of system has proven to have advantages over water base mud systems previously used.

After detailed laboratory studies of attapulgite, bentonite, sepiolite and saponite clays in conjunction with polymers and various salts, a system using a mixture of saponite/sepiolite for the primary viscosifier has been developed.

The rheology of most clay slurries can be controlled by high molecular weight and low molecular weight temperature stable polymers. Potassium salts such as potassium bicarbonate and potassium carbonate are used instead of the sodium salts to control the alkalinity and chemical base exchange of clays. Potassium salts of the polymers are also used instead of sodium salts in order to maximize the potassium availability and minimize the sodium content.

These systems can be used in almost any type of make-up water and can be increased in density for control of high pressure-high temperature environments. They have been used for drilling in both shallow and deep wells, including wells of total depths below 17,000 ft. In addition to small diameter holes; these systems also show excellent hole cleaning ability and borehole stability in large diameter holes drilled for mine shafts.

These systems have temperature stability above the 500°F (254°C) range and with correctly chosen chemicals, show inhibition to water sensitive clays when run at intermediate pH range. They are easy to test and maintain and can result in faster drilling rates, improve hole cleaning, better cement jobs and minimal formation damage; and, add a more economical approach to drilling fluids. In addition, the environmental aspect is extremely appealing.
A Single Technique Solves Gas Migration Problems Across a Wide Range of Conditions
Authors: Drecq P. , Parcevaux P. A.
Published: December 2007

The problem of annular gas migration following primary cementing is analyzed, and the main mechanisms responsible for its occurence within the cement matrix or at the cement to formation interface are described.

The emphasis is put on a special technique that has proved, through extensive field usage, to solve the problem in widely varying conditions, such as shallow gas from weak zones, very high pressure formations, interlayered gas and water sensitive zones. Such conditions involve slurry density from 10 to 22 lbm/gal, downhole temperature from 10 to 180° C, and mix water from fresh to 18% NaCl.

This technique is based first on the proper displacement of the drilling mud through good cementing practices, and then on the placement in the annulus of a well dispersed, non gelling, impermeable cement. The key of this system is a latex additive, that, through its film forming property, locks the cement permeability to gas when the gas attempts to permeate under a differential pressure.

For such a system to perform optimally, cement pore pressure drop is delayed as much as possible, through the use of proper dispersants that inhibit premature cement gelation. Then the transition time between the liquid and the set state is shortened by chemical stabilizers of the latex. Finally, cement permeability to gas is controlled during cement thickening and setting, and cement to pipe and to formation bonds stay durable for the whole life of the well, and this is achieved through the latex itself.

Field applications of this system are presented through several case histories illustrating typified normal and extreme situations.
Preparation of Two Polymer Pilot Tests in Daqing Oil Field
Authors: Chauveteau G. , Combe J. , Dong Han
Published: December 2007

Information relative to the preparation of two polymer flood pilots in the West Central Saertu area of the giant Daqing oil field in China is presented.

The reservoir features of the West Central area of the field contribute to suggest polymer injection as an attractive process. Numerical simulations as well as economical calculations based on anticipated optimum operational conditions have confirmed this interest.

The primary scope of the reported laboratory study is the use of a new methodology for selecting the most appropriate polymer chemical structure. Three main selection criteria, namely maximum intrinsic viscosity, minimum adsorption and absence of attractive polymer-polymer interactions were considered and a Polyacrylamide containing 20% of acrylate group was chosen. This polymer was found to show high effective viscosity and low retention in core flows. A xanthan sample also suitable according to these technical criteria was not considered due to economical reasons.

The two pilot tests are being designed on these bases. The first one aims at checking the ability of polymers to reduce vertical channeling within a single layer. The second will evaluate the improvement of vertical sweep efficiency when two separate layers open in wells with single completions are subjected simultaneously to polymer injection. The well layout of each pilot and the type of information expected from the observation wells are described.
Field Experience with the GRI Rheology Unit
Authors: Ely J. W. , Haskett S. E. , Holditch S. A.
Published: December 2007

During the past five years, the Gas Research Institute has developed a comprehensive fracture fluid evaluation laboratory that is portable and is used in the field to monitor actual fracture fluid systems. Although many components of the GRI Rheology Unit are available elsewhere, no other organization offers a system that can be used in the field to fully characterize a fracture fluid before and during an actual fracture treatment.

One of the objectives of the GRI research effort is to run 3-D fracture models in real time to improve our understanding and control of hydraulic fracture treatments. The 3-D fracture models are used to history match the values of excess pressure vs. time in order to determine fracture size and shape. We have found that unless one can fully characterize the fracture fluid viscosity vs. time, temperature and shear rate, then the fracture shape computed using a 3-D fracture model will be non-unique.

To more fully explain this concept, one must understand the mechanisms that affect the excess pressure in a fracture during the treatment. The excess pressure is dominated by friction pressure as the fluid flows down the fracture. The friction pressure is affected by both the viscous properties of the gel and the shape of the fracture. We can only determine the shape if we know the viscous properties of the gel beforehand. Therefore, to improve our use of 3-D models in this research, we have determined that we must go to the field and accurately measure the viscous properties of the fracture fluid.

In the early stages of the program, most of our efforts involved surface quality control and real time monitoring of fluid parameters during the pumping operation. Although the importance of quality control and pre- and post-job materials inventory cannot be overemphasized, we have found that a more intense effort is required to quantify the viscous properties of the actual fluid on site.
Acoustic Emission Interpretation for Estimating Hydraulic Fracture Extent
Authors: Sarda J-P. , Perreau P. J. , Deflandre J-P.
Published: December 2007

It is useful to map hydraulic fractures in order to improve the rate of success of such operations and to optimize the pattern of stimulated wells. The proposed method can be used during a minifracturing or prefracturing operation and necessitates a downhole 3D acoustic detector clamped in the well. A few to a few dozen cubic meters of gel being injected during fracturing phases, the acoustic activity is recorded after every injection, then signals containing apparent P and S waves are analyzed to determine the directions and distances of the emitting sources. A number of arrivals cannot be easily interpreted, in particular those corresponding to refractions along the casing. Two field examples corresponding to a vertical and an inclined fracture are given. Knowing the P and S wave velocities in the different layers and a careful choice of the tool position are essential to the success of the method.
Improved Rock Property Measurements Using Core from the Travis Peak Formation
Authors: Narahara G. M. , Holditch S. A.
Published: December 2007

The advancement of technology in producing tight gas sands requires rock property measurements involving the flow of fluids in cores. The purpose of this paper is to present measurements of absolute permeability, total porosity, capillary pressure, and gas relative permeability on several Travis Peak cores. Even though such measurements are difficult to obtain, the resulting values are needed to accurately model gas flow in such reservoirs.

A transient test method developed in the early portions of this research has been used to measure absolute permeability and total porosity as a function of net stress. The net stress on the cores was increased to simulate the depletion of the reservoir pressure, and the results can be used to observe the effect of formation compressibility on permeability and porosity.

A study of gas slippage was performed using the transient test method. Several parameters, including gas molecular weight, net stress, and flow rate, were varied to determine their relationship with gas slippage. It was found that gas slippage can be affected by the slot-pore geometry found in highly cemented, low permeability formations.

Since water is pumped into low permeability formations during stimulation treatments, two-phase rock property measurements are important if one wishes to model the effects of the water upon gas recovery. The measurement of capillary pressure and gas relative permeability have been investigated in this study.

The ultracentrifuge presents a practical method for determining capillary pressures in low permeability cores. Several cores were run and the capillary pressure data are presented. Saturation equilibrium was determined by monitoring each centrifuge speed over a 24 hour period. An analysis of the continuity of the displaced phase has also been performed.

A new method recently developed in this research has been used to measure the gas relative permeability and water saturation simultaneously. The new method presents a rapid means of generating the entire gas relative permeability curve. The results from two Travis Peak cores are presented.

In summary the results of these measurements on absolute permeability, total porosity, capillary pressure, and relative permeability present a description of the rock properties for studying fluid flow in a typical tight gas formation. The system of measurements can be performed on any low permeability core on a routine bases.
The Impact of System Capacitance on Gas Pipeline Facility Design
Authors: Richwine T. E. , Schroeder D. W.
Published: December 2007

In the design of natural gas transmission facilities it is important to consider the time-varying nature of most gas demands. Steady-state analysis may or may not be adequate depending on both the characteristics of the demands and the transportation system. This paper attempts to point out the factors that are of importance as system loads change and quantify them where possible. Criteria for determining the appropriate analysis techniques are discussed along with an example of the relative impact of adding in-line compression versus additional pipeline.
Two Products for Gas Network Calculation in Interactive Graphic Mode for the Size of Installations and for Computer-Aided Network Operation
Authors: Deola M. , Bonnel J-C.
Published: December 2007

Gas companies have long felt the need for flow modelling in natural gas transmission and distribution systems.

With the emergence of digital processing of the information related to an in_depth physical study of gas phenomena it became possible to develop network calculation. And, the evolution of DP hardware combined with their ever decreasing cost expanded their use.

Two main categories of applications make use of these calculations: pipeline sizing studies and pipeline management network monitoring and control

The first category corresponds to static applications where the totality of the network's component parts have to be considered in order to find a technical economic optimum of the capital investments both as concerns network reinforcements and network extensions.

The second category entails the analysis of dynamic physical quantities such as flow rates and instantaneous pressures acquired and processed in real. time. In this case, the aim is to give the monitoring station operator a snapshot of his network and prediction of its behavior under various operating configurations.

The present paper analyzes the DP hardware and software suitable for these two kinds of application and pays special attention to the interactive and ergonomic aspects.
Medium-Pressure Township Gas Distribution System Design
Authors: Yassin A. A. M. , Shariff Z. A. M. , Hee P. C.
Published: December 2007

The paper discusses the implementation and the design concept with respect to the so termed Medium Pressure Township Gas Distribution System for providing Malaysia's townships gas distribution facilities which include means of residential and small commercial uses only.

The implementation of medium pressure which ranged from 1.0 to 15.0 psig. is particularly suitable for Malaysia's environment, in which, the service area to be covered is large in size, but the gas consumption rate is relatively small. The application of medium pressure ensured the regular supply of gas to all customers at right pressure and achieve a reduction in investment costs.

Significances of applying medium pressure and procedures of designing Medium Pressure Township Gas Distribution System are presented in the paper. Hardy Cross Network Analysis Method, which is used in the modeling of gas distribution system also being discussed in the paper.
Inert Gas Injection as Part of the Cushion of the Underground Storage of Saint-Clair-Sur-Epte, France
Authors: Laille J-P. , Molinard J-E. , Wents A.
Published: December 2007

Building part of the cushion of an aquifer underground gas storage by an inert gas produced at a much lower cost than pipeline gas, is an operation of high economic interest.

The paper presents the actual case history of the underground aquifer gas storage of SAINT-CLAIR-SUR-EPTE, FRANCE. Preliminary studies performed in 1978 and 1979 have shown the technical feasibility and economic interest of injecting a significant quantity of inert gas (20 % of the cushion gas) before filling up the storage with natural gas.

The inert gas injection actually began on the 6th of August 1979 to reach a total inventory of 60.2 106 m3(n) on the 14th of March 1982. The first natural gas injection began on the 19th of August 1981 as the total inert inventory was 50.4 106 m3(n), and the first withdrawal took place on the 15 of November 1983, with a total inventory (inert + natural gas) of 462.6 106 m3(n). It should be noted that the inert gas injected contained a small proportion of air. The storage was operated since with injection-withdrawal cycles, the total working capacity (247.6 106 m3(n)) was withdrawn during winter 1986-1987.

The concentrations of gas components obtained from chromatography were collected on a set of eleven observation wells, at a rather important frequency (once a month on 7 wells during the withdrawal period of winter 1986-1987), giving the natural gas and inert concentrations. The plotting of curves, as well as the mapping of concentrations of inert and natural gas permits to have a good control of the gases repartition inside the porous medium. The proportion of O2 and CO2 were also analysed on the same observation wells. The evolution with time of these two variables is interesting and will be presented In the paper.

As far as we know, for the first time, a storage with a cushion consisting of 20 % of inert gas has been successfully operated for several years. The synthesis of the field data and its interpretation is included in the paper.
Pipeline Corrosion Logging: A New Application of Wireline Surveys
Authors: Edwards R. C.
Published: December 2007

The use of wireline measurements in gas storage gathering lines is a new idea which addresses the problem of internal and external corrosion in pipelines. Gathering lines are subjected to the same corrosive agents (H2O, CO2, H2S, etc.) as gas storage wells. However, unlike storage wells, where wireline surveys are utilized to monitor metal loss, the level of damage in the gathering lines is largely unknown. Most of the other corrosion monitoring methods are not direct measurements of corrosion. While pipeline inspection pigs detect corrosive damage they have limited application due to the gathering lines relatively short lengths and small diameters.

The use of the Pipeline Corrosion Tool and Video Camera introduces a precise means to completely inspect pipelines. Metal loss is detected and then correlated to a video survey. Both tools have been physically designed to traverse the extreme bends found in gathering systems. Pipeline logging is an accurate and ecomonically attractive alternative for detection of internal and external corrosion in pipelines.
World Gas Supplies, Markets, and Trade
Authors: Jensen J. T.
Published: December 2007

Worldwide natural gas consumption has increased over the last ten years, but the gains have been regionally uneven. Growth rates have been high for Japan and Australasia, as well as for many developing countries with gas discoveries of their own. But the U.S. fell to a twenty-one year low in 1986 and gas markets have stagnated in such important European markets as Germany, France and the Netherlands. The effect of disparate regional demand patterns on international gas trade, especially LNG, has been to reduce expectations well below those of the early 1970s.

While proved gas reserves worldwide compare favorably to those of oil, many gas discoveries are remote from consuming markets, and thus costly to commercialize. Less than half of the world's total gas reserves are dedicated to specific local or export market outlets. An equally large quantity of gas may also be classified as exportable surplus -- large enough to support an export project, but with no market outlet yet available. Since new export commitments are not growing as rapidly as gas discoveries in major export regions, the exportable surplus category is steadily increasing.
Study of the Ab’ei Andesite Reservoir in Erlian Basin
Authors: Jieting Tang , Jiaren Yu
Published: December 2007

The characteristics of the andesite reservoir have been studied in terms of drilling » logging and coring data of the A’bei andesite oil pool in Erlian Basin. A preliminary study has shown the following five characteristics’ (1) a variety of textures and structures of reservoir rock* (2) fractures as the major reservoir and migration space; (3) high water saturation; (4) anisotropic fluid flow m porous media; (5) alternation of good and poor reservoirs in a vertical section. The oil pool is a vesicular micro - fracture type reservoir. The anisotropic fluid flow will lead to a complex flow pattern, resulting in a unique production performance. So effective development methods should be adopted to achieve higher recovery.
Analysis of Pressure Transient Testing for Damaged Wells and Automatic Technique for Matching with Type Curves
Authors: Wening Liu , Qinlei Chen , Jianru Yang , Zhengchuan Sun
Published: December 2007

During drilling and well completion, the drilling fluids may damage the formation nearby bottom hole and reduce its permeability. Stimulation treatment, such as fracturing and acidizing, in turn, may improve the permeability of this zone. As a result, a permeability variation zone will be probably formed around a well. It is one of the important reservoir engineering problems to determine the range of the zone and the degree of permeability variation. A transient well test interpretation model (composite sandstone reservoir mode D together with the new type curves are presented in this paper, which are based on the geological and development features of some China’s oilfields and can be used to determine the effects of damaged zone and outer boundary. In view of the nonuniqueness in manual matching, a computer automatic matching software is also established in accordance with the new type curves.
Relief Well Drilling Technology
Authors: Xiu Yu , Jinling Jie
Published: December 2007

This paper summarizes the technology of relief well drilled in China. In recent years, four relief wells have been drilled, the distances of which to the target are 3.81m, 6.84m, 4.45m and 2.29m respectively.

"Three Section" profile for the relief well is recommended. The drift of well path should be controlled within 10m from the target point before hitting the target. The final azimuth correction should coincide with the closed azimuth line of the blowout well, and then a tracking method is used to drill towards the target area, so as to achieve the goal by communicating two wells and killing the blowout well.
Energy Saving In NGL Recovery Plant
Authors: Wang Yudong , Xiang Xinyao , Jiang Huijuan
Published: December 2007

Based on the result of exergy analysis on a pilot NGL recovery plant which uses low presure associated gas (LP-gas) as feed, the possible way of saving energy by this kind of plant is discussed.
Study of Property of Cationic Surfactants for Preventing Clay from Swelling
Authors: Yizhen Lu
Published: December 2007

This paper demonstrates a new cationic surfactant SQ-G which is used as a clay swelling inhibiting additive in water-base crosslinked fracturing fluid. It has a better performance than other additives available for clay swelling inhibiting. In addition, it also plays some role in viscosity increasing, corrosion inhibiting, bacteria-killing and emulsion breaking etc..

This additive is added into the fracturing fluid during its preparation. Its advantages ares low amount of addition, no requirement of special equipment and technique, good compatibility with both fracturing and formation fluids and no formation damage.

A large number of in-house simulation tests and field tests have proved that the new additive has very good properties. Currently, it has been widely used in field operation, and good results are obtained.
Grey System Method for Predicting Performance of Oil and Gas Fields (Wells)
Authors: Pingyi Lin , Dachang Li
Published: December 2007

At the Present time, the empirical methods are always used in the prediction of production performance of oil and gas reservoirs (or wells). For example, for presanting the production decline there are exponential, hyperbolic, and harmonic decline methods. All these methods are effective only when the production data of the oil and gas reservoirs change steadily. However, in many cases, the production is not a stable process, especially for the gas reservoirs (or wells) and the small fault-block ed oil reservoirs. In such cases, the effectiveness of the empirical methods is limited. In this paper, a grey system method which has been proved effective in sociology, economics, and other fields is introduced to predict the performance of oil and gas reservoirs (wells). Six grey system prediction models are proposed, namely, DM(1, 1), DM(1, 2), DM(l, 3) DM(2, 1), DM(2, 2) and DM(2, 3). This paper describes these models and give out the results predicted for a gas reservoir, a gas well and two oil reservoirs as examples. As it has been shown in these examples, the methods proposed is practical, reliable and relatively simple. The calculations of the these prediction models can be simultaneously performed on a portable computer (such as PC-1500).
Experimental Study Of Exploring Natural Gas Formation With Compressional Wave Amplitude And Results Of Its Application In The Field
Authors: Tingdong Tan , Ning Li , Houyi Li
Published: December 2007

This paper gives the experimental results about the relations between velocity, amplitude, and dominant frequency of compressional head wave and gas saturation. The head wave amplitude is an important indicator of gas - bearing formation beause it is more sensitive to gas saturation than its velocity and dominant frequens Discussion of the methodology of using amplitude (energy) attenuation to detect gas-bearing formation is presented and evaluation of the characteristics, effectiveness, influencing factors, and problems of this method is made in the light of its application in 30 wells in Huabei, Sichuan and Zhongyuan oil fields.
Development In The Limited--Entry Completion Fracturing Technique
Authors: Wang Zhou , Wenhui Qi , Tongshou Xiao , Shijing Pan , Chaoyang Xie
Published: December 2007

The limited entry fracturing technique is considered feasible for treating the thin and lover permeability sandstone interbeded with shale in Daqing Oil-fields, in case that horizontal fractures are induced. 15 to 20 individual sandstone layers can be treated without the need of manipulating the tubing string during one fracturing job with small volumes. Various types of post-fracture tests revealed that 80–90% of the objective formations are stimulated. The key points for limited entry completion fracturing technique lie in the accurate interpretation of watered out thin layers, high resolution, low density perforation, and the use of separated-layer fracturing string.
Laboratory Experiment Of Foaming Drilling Fluid And Study Of Its Application In The Field
Authors: Shizhong Fan , Wenyi Li , Jianyao Xie , Rongkui Yao
Published: December 2007

The low pressure, medium-low permeable reservoirs, which make a good percentage in China, play an important role in expending reserves and increasing production. The foam fluid, which is widely used in the world, is one of the low density drilling fluids that is required to explore and develop this kind of reservoir.

This paper contains a description of the evaluation of the foam fluid available,- the study of the foam formula and its stability. The development of a computer program, the tests on a simulating well and the up-dated field application of foam in oil fields are also described.
Engineering Study For Development Of A Special Marginal Oil Field In South China Sea
Authors: Ying Wei
Published: December 2007

This paper mainly deals with the engineering study of the development of a special marginal oil field located in adverse sea environment in South China Sea under rhe backgro und of sharp decline of oil price. This oil field is at a water depth 100m. with less favorable geological condition and limited crude reserve. The saturation pressure of reservoir is low and the capablity of natural flow is also limited. The oil-gas ratio of the crude oil produced from such a field is 1. and the single-well production of the oil field is rather low. The paper is to analyse the main factors influencing the economic benefit of the development of the oil field. On this basis, analysis and comparison of various options are made so as to define a technically feasible and economically viable scheme for development.
Predicting Deepwater Fracture Pressures: A Proposal
Authors: Simmons E. L. , Rau W. E.
Published: December 2007

The accurate prediction of formation fracture gradients has historically been a matter of great concern, for well planning purposes and "real time" drilling considerations. When the proposed drilling environment is at substantial water depths (greater than 350 feet), the concern for a viable predictive technique, and the accuracy of such a technique has been a problem of some magnitude.

This paper proposes and recommends two techniques for predicting formation fracture pressures in offshore drilling environments where the water depth is greater than 350 feet. The first technique suggests a modification of Eaton's method which he proposed in his paper published in 1969. His work is modified to account for the affect of a water column on the composite vertical rock stress at the point of interest. The second technique suggests a method of bulk density log integration to accurately define the overburden stress at any point of interest. This technique provides a method for "real time" evaluation of a proposed casing setting depth prior to running and cementing casing. The results of such an analysis could provide the opportunity to deepen a particular hole segment thereby creating a safer, more stable, and under most conditions, a more economical drilling environment.

The recommendations proposed in this paper are the direct results of work done at Chevron's Drilling Technology Center. The project involved a comparative analysis of existing predictive techniques relative to actual leak-off test data from deep water wells drilled by Chevron Operating Companies worldwide. Statistical analysis have definitely shown that these proposed techniques will provide improved accuracy in this critical area of deep water exploration.
Other Unconsolidated Formations in Vertical and Inclined Holes
Authors: Wilson M. A. , Beirute R. M. , Sabins F. L.
Published: December 2007

A project to investigate the cement placement process across heavy oil sands was conducted to help explain some of the problems experienced by a major oil company when cementing casing in a field in Canada. These problems were related to poor quality of primary cementing jobs as suggested by cement bond logs.

Various factors affecting mud displacement efficiency were examined using a 15 ft long test annulus comprised of three 5 ft formation sections. Conventional cementing equipment and practices were used in the experiments. Following completion of individual tests, the cement was allowed to set and the test section was cut into cross sections to measure displacement efficiency (percentage of mud removed) and visually examine the character of the cement sheath.

Factors affecting mud displacement efficiency and preservation of formation integrity examined in the course of this investigation included the following: Effect of drilling fluid filter cake deposition, its prevention, and removal.Influence of pipe movement (rotation/reciprocation) with and without mechanical casing hardware (cable wall cleaners/centralizers).Effects of pipe centralization, hole washouts.Use of spacers/flushes to improve displacement efficiency.Influence of displacement rates on mud removal efficiency.Examination of above factors under deviated hole conditions.

Findings resulting from this research investigation are presented, including recommendations to improve cementing results across heavy oil or other soft, unconsolidated formations in both vertical and inclined holes.
Permeability Microstratification in Natural Sandstones
Authors: Holden W.R. , Caudle B.H.
Published: December 2007

Spherical flow tests in sandstones indicated a strong tendency for flow to follow the natural bedding planes. These results suggested that a cylindrical flow pattern be studied in the same rock. The latter tests for the ten samples studied, showed an unexpected type of microstratification. The flow took place in thin (0.1 inch thick) horizontal laminae. The apparent permeability of adjacent laminae varied widely in many cases. It is believed that this type of microstratification—if continuous—would cause premature breakthroughs and poor performances in gas cycling and miscible displacement projects.

Introduction

Darcy's law has always been the basis of reservoir engineering methods. In its infancy, reservoir engineering consisted mostly of predictions of fluid production as a function of the amount of drawdown in the production well. For this purpose, Darcy's law could be used in its simplest form— which points out that the flow rate of any fluid through a porous medium of any type or geometry is directly proportional to the pressure drop across the system. Later attempts to study problems such as water coning and the effects of well bore damage required the use of Darcy's law as a differential equation of flow at a point:
Simultaneous Multiple Entry Hydraulic Fracture Treatments of Horizontally Drilled Wells
Authors: Austin C. E. , Rose R. E. , Schuh F. J.
Published: December 2007

The number of horizontally drilled wells has continued to increase in the past few years. Nearly all of these well s have been completed as "drainholes" with slotted or perforated liner and without a cement sheath. The majority of these have been successful in their designed intent.

Hydraulic fracturing treatments have been performed on a relatively small number of these wells. To be effectively fracture stimulated, a horizontally drilled well must be cased and cemented through the horizontal producing section of the well. Casing and cementing the horizontal section allows fracture initiation points to be controlled in placing multiple fractures.

In situ stresses greatly influence the potential effectiveness of any fracturing treatment procedure. The one factor which most directly affects horizontal wellbore fracturing is the least principal stress, which is at a right angle to the induced fracture. The direction of the horizontal segment of the borehole dictates whether or not the induced fracture will be parallel or at an angle to the borehole.

The use of properly applied controlled entry techniques at several fracture initiation points will help allow equal placement of proppant or reactive fluids in one stimulation treatment. Ei ther fracturi ng wi th proppant or fracture acidizing can be used in the stimulation treatment. The potential economic benefit to be derived from a successful multiple entry fracturing treatment merits strong consideration be given to the development of fracturing techniques to help obtain maximum wellbore drainage.

Subject paper explains techniques and methods to be used in creating and placing proppant and/or reactive fluids in each of the multiple fractures in a horizontally drilled well. Economic considerations of the simultaneous stimulation treatment procedure are presented and compared to a vertical well under similar conditions.