Long An Province

Journal of Petroleum TechnologyJanuary, 2021

Planning Industry Events: Setting Them Up For Success

From workshops to technical courses, annual conferences to niche forums and symposiums, the oil and gas industry offers a diverse assortment of knowledge sharing opportunities. While you may have attended one (or many) of these events, have you ever considered the planning that happens behind the scenes of these events? Planning industry events is a great way to build a network, develop project management skills, practice public speaking, and perfect the art of efficient email communication. Throughout my career, I have either directly planned or supported the planning efforts for more than 20 industry events. I am by no means an expert event planner, but I have had ample opportunity to consider how long an audience can pay attention (not long), hold their bladder (slightly longer than you think), and require coffee or snacks (morning and afternoon).

Journal of Petroleum Technology

audience, coffee, committee member, event planning, event schedule, industry event planning, knowledge management, lead time, planning committee, Planning Industry Event, selection

Country: Asia > Vietnam > Long An Province (0.25)

Industry: Energy > Oil & Gas (0.55)

SPE Disciplines:

Management > Professionalism, Training, and Education (0.55)
Data Science & Engineering Analytics > Information Management and Systems > Knowledge management (0.35)

Technology: Information Technology > Communications > Collaboration (0.35)

Electrochemical Crack Size Effect in Stress Corrosion Cracking and Corrosion Fatigue

Turnbull, A. (National Physical laboratory) | Zhou, S. (National Physical laboratory)

OnePetroMarch, 2017

ABSTRACT The growth rate of small and long stress corrosion and corrosion fatigue cracks in 12Cr steam turbine blade steels in low conductivity water containing 35 ppm Cl (simulating upset steam condensate chemistry) showed a significant dependence on crack size for the same mechanical driving force. However, the crack-size effect disappeared in lower conductivity solution, 300 ppb Cl and 300 ppb SO4(corresponding to normal steam condensate chemistry). Furthermore, corrosion fatigue long crack growth rates were the same in aerated and in deaerated solutions for the two environments but stress corrosion cracks arrested in deaerated solution. An explanation for these varied results is presented based on the concept of the solution-conductivity dependent crack size effect and its impact on potential drop and hence the crack-tip potential. To underpin this conceptual idea and to explore further the scale of this effect for varied crack size and solution conductivity combinations, modelling of crack electrochemistry is being undertaken and the preliminary results are described. INTRODUCTION Characterising the growth rate of cracks in the small crack regime in aqueous solutions is a major challenge in applications where the time-dependent growth rate is very small and test times can be inordinately long. An example is the laboratory simulation of regular start-up and shut-down of steam turbine systems for conventional power stations. Regular start-up and shut-down has become more prevalent for economic reasons and increasingly to balance out fluctuating electricity supply from renewable energy sources such as wind. Typically a hot start involves a 20 min rise time and then a long period of hold. Off-load the steam turbine condensate is aerated (leakage through gland seals) while under steady-load conditions the condensate becomes oxygen-free with the oxygen level in the turbine chamber decreasing progressively with time over a period of 48 hours. As such, during the hold period in start-stop operation the oxygen concentration is not precisely known but some degree of aeration has to be assumed. There is uncertainty regarding the impact of start-up and shut-down on turbine lifetime, recognising also that control of boiler water chemistry is often not ideal. Excursions in chloride concentration can occur such that the condensate water chemistry can be more aggressive than that expected for normal water chemistry operation. In the latter case, this is typified by 300 ppb Cl and 300 ppb SO4 but the condensate chemistry due to uncontrolled excursions can vary markedly, and in limiting situations during start-up can approach that of seawater (associated with a seawater cooled condenser leakage). The latter is an extreme situation and more commonly excursions in chloride ion concentration are modest, though with an inherent variability from plant to plant. Although arbitrary, a chloride ion concentration of 35 ppm has been adopted as a reference concentration in exploring the effect of operational variables for both start-up and shut-down conditions and also for situations where sustained oxygen ingress could lead to the risk of stress corrosion cracking.

NACE

NACE-2017-8853

CORROSION 2017

Country:

Europe > United Kingdom (0.28)
Asia > Vietnam > Long An Province (0.24)
North America > United States > Texas > Harris County > Houston (0.15)

Industry: Energy > Oil & Gas > Upstream (1.00)

SPE Disciplines:

Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)

Cyclic Tests of Model Pipe in Kaolin

Aubeny, Charles P. (Texas A&M University) | Gaudin, Christophe (University of Western Australia) | Randolph, Mark F. (U of Western Australia)

OnePetroDecember, 2008

Summary Soil-pipe interaction is an important factor in the design of steel catenary risers. Pertinent aspects of this issue include the backbone curve defining soil resistance under conditions of virgin penetration, equivalent soil spring stiffness during unload-reload cycles, and permanent displacements under cyclic loading. This paper presents the findings of single-gravity model tests in soft kaolin that were conducted to investigate these issues. Cyclic tests were conducted for small amplitude loading involving no reversal in the direction of the soil-resisting force, and large amplitude loading involving such reversals. Presented in this paper are measured relationships of soil secant stiffness as a function of displacement and load cycle for conditions of unloading and reloading. The rate of accumulation of permanent displacements under cyclic loading is strongly affected by the magnitude of loading. Backbone curve measurements during virgin penetration are in general agreement with analytical estimates. The laboratory-model test data were used to derive seabed stiffness parameters for a seabed-riser interaction model. An example analysis is presented for a typical steel catenary riser touching down on a soft seabed. Introduction Interaction effects between seafloor soils and shallowly embedded pipes are relevant to a variety of pipeline problems. A topic of considerable current interest is soil-pipe interaction within the zone where a riser pipe touches down on the seabed, which proves to be a region where changes in bending stresses are largest and therefore a critical location for fatigue (Bridge et al. 2003, 2004). A P-y approach similar to that applied to laterally loaded piles is often adopted for this problem, where P is soil force per unit length of pipe (F/L) and y is deflection normal to the pipe axis. In the study presented herein, the focus is on vertical motions, and y denotes vertical deflection. Development of a P-y model requires characterization of the following aspects of soil-pipe interaction:The "backbone" curve describing force-penetration (P-y) behavior under conditions of virgin penetration. Equivalent soil spring stiffness under conditions of unloading and reloading, and the change in stiffness during cyclic loading. Permanent deformations under cyclic loading. This paper presents the results of a testing program developed for the purpose of elucidating basic aspects of soil-pipe interaction behavior with regard to the points listed previously. Test Program The test program presented herein comprises three tests conducted under single gravity conditions. The first is a reference test that establishes the backbone curve and stiffness relationships to be used as a basis for evaluating cyclic test data. The second test involves "small-amplitude" cyclic loading conditions, which in this paper will refer to cyclic loads of sufficiently small magnitude such that no reversal of direction occurs in the net soil force acting on the pipe. The third test is a "large-amplitude" cyclic load test in which the pipe undergoes a large (1D) upward displacement during each load cycle and a reversal of the net soil force on the pipe occurs. Test Apparatus. The tests were conducted in a kaolin test bed contained in strong box with internal dimensions, 650 mm by 390 mm by 325 mm deep. The consolidated thickness of the kaolin was 220 mm. The model pipe dimensions were 25 mm diameter by 125 mm long. An electronically driven actuator allows both T-bar and pipe penetration tests to be undertaken. The data acquisition and control software permits loading with either displacement or force control. A displacement control mode with load reversal at a prescribed force level is also possible, a feature which was utilized in the large-amplitude cyclic load test. Soil Properties. Shear strength of the kaolin test bed was measured with a 5-mm diameter by 20-mm long T-bar (Stewart and Randolph 1994) penetrated at a rate of 1 mm/sec. Fig. 1 shows the inferred strength assuming a T-bar factor of 10.5. A linear regression analysis of the strength profile, excluding the top 20 mm owing to free surface effects, yields a strength intercept of 3.7 kPa with a slight negative strength gradient of -0.0029 kPa/mm. The negative strength gradient is a likely consequence of incomplete consolidation in the test bed. Because the intent of this testing program is to test the pipe under conditions of known soil strength, but not necessarily under strength gradient conditions representative of field conditions, the resultant strength profile is considered satisfactory.

doi: 10.2118/123131-PA

SPE Projects, Facilities & Construction

SPE-123131-PA

Country:

North America > United States (0.28)
Europe (0.28)
Asia > Vietnam > Long An Province (0.24)

Geophysics: Geophysics (0.34)

Industry: Energy > Oil & Gas > Upstream (1.00)

SPE Disciplines:

Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Risers (1.00)
Data Science & Engineering Analytics > Information Management and Systems (1.00)

Technology: Information Technology > Artificial Intelligence > Machine Learning > Statistical Learning > Regression (0.54)

Cyclic Tests of Model Pipe in Kaolin

Aubeny, Charles Paul (Texas A&M University ) | Gaudin, Christophe (University of Western Australia) | Randolph, Mark Felton (U. of Western Australia)

OnePetroMay, 2008

Abstract Soil-pipe interaction is an important factor in the design of steel catenary risers. Pertinent aspects of this issue include the backbone curve defining soil resistance under conditions of virgin penetration, equivalent soil spring stiffness during unload-reload cycles, and permanent displacements under cyclic loading. This paper presents the findings of single-gravity model tests in soft kaolin that were conducted to investigate these issues. Cyclic tests were conducted for small amplitude loading involving no reversal in the direction of the soil resisting force, and large amplitude loading involving such reversals. Presented in this paper are measured relationships of soil secant stiffness as a function of displacement and load cycle for conditions of unloading and reloading. The rate of accumulation of permanent displacements under cyclic loading is strongly affected by the magnitude of loading. Backbone curve measurements during virgin penetration are in general agreement with analytical estimates. Introduction Interaction effects between seafloor soils and shallowly embedded pipes are relevant to a variety of pipeline problems. A topic of considerable current interest is soil-pipe interaction within the zone where a riser pipe touches down on the seabed, which proves to be a region where changes in bending stresses are largest and therefore a critical location for fatigue (Bridge et al., 2003; Bridge et al., 2004). A P-y approach similar to that applied to laterally loaded piles is often adopted for this problem, where P is soil force per unit length of pipe (F/L) and y is deflection normal to the pipe axis. In the study presented herein the focus is on vertical motions, and y denotes vertical deflection. Development of a P-y model requires characterization of the following aspects of soil-pipe interaction:The ‘backbone’ curve describing force-penetration (P-y) behavior under conditions of virgin penetration. Equivalent soil spring stiffness under conditions of unloading and reloading, and the change in stiffness during cyclic loading. Permanent deformations under cyclic loading. This paper presents the results of a testing program developed for the purpose of elucidating basic aspects of soil-pipe interaction behavior with regard to the points listed above. Test Program The test program presented herein comprises three tests conducted under single gravity conditions. The first is a reference test that establishes the backbone curve and stiffness relationships to be used as a basis for evaluating cyclic test data. The second test involves ‘small amplitude’ cyclic loading conditions, which in this paper will refer to cyclic loads of sufficiently small magnitude such that no reversal of direction occurs in the net soil force acting on the pipe. The third test is a ‘large amplitude’ cyclic load test in which the pipe undergoes a large (1D) upward displacement during each load cycle and a reversal of the net soil force on the pipe occurs. Test Apparatus. The tests were conducted in a kaolin test bed contained in strong box with internal dimensions, 650 mm by 390 mm by 325 mm deep. The consolidated thickness of the kaolin was 220 mm. The model pipe dimensions were 25 mm diameter by 125 mm long. An electronically driven actuator allows both T-bar and pipe penetration tests to be undertaken. The data acquisition and control software permits loading with either displacement or force control. A displacement control mode with load reversal at a prescribed force level is also possible, a feature which was utilized in the large amplitude cyclic load test.

Offshore Technology Conference

doi: 10.4043/19494-MS

OTC

OTC-19494-MS

Artificial Intelligence, backbone curve, cyclic loading, displacement, load cycle, load reversal, loading, Midstream Oil & Gas, Offshore Technology Conference, penetration, pipe, reload stiffness, resistance, reversal, secant stiffness, sequence, soil resistance, stiffness, Upstream Oil & Gas

Country:

North America > United States > Texas (0.29)
Oceania > Australia (0.29)
Asia > Vietnam > Long An Province (0.24)

Geophysics: Geophysics (0.48)

Industry:

Energy > Oil & Gas > Upstream (0.48)
Energy > Oil & Gas > Midstream (0.46)

SPE Disciplines:

Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Risers (1.00)
Data Science & Engineering Analytics > Information Management and Systems (0.86)

Technology: Information Technology > Artificial Intelligence (0.31)

Acid Number Measurements Revisited

Fan, Tianguang (New Mexico Tech) | Buckley, Jill S. (New Mexico Tech)

OnePetroDecember, 2007

Summary We propose an improved procedure for measuring acid numbers. Major changes include spiking crude oil samples and blank solutions with a known amount of stearic acid to force a clear titration endpoint, replacing potassium hydroxide with tetrabutyl ammonium hydroxide in the alcoholic titratant, and correctly accounting for changes in electrode response that occur upon exposure of the electrode to crude oil. Introduction Chemical methods of improved oil recovery are not equally effective in all reservoirs. An important factor that can influence a project's success is crude oil composition. Because crude oils are complex mixtures, evaluation of oil composition in a way that is meaningful with respect to specific chemical recovery processes can present many problems. In particular, there is a need for improvements in acid number (AN) measurements, also known as total acid number (TAN). AN is important in evaluating crude oils for alkaline and surfactant processes, but in order to be useful, measurements must be comparable from one laboratory to another and must also capture chemically meaningful information about the crude oil. Standardization (e.g., the current ASTM recommended procedure) should assist with the first requirement: that different labs be able to reproduce the AN value within some reasonable tolerance. Standardization does not, however, ensure that the measurement captures information about a crude oil that can be used to predict its interactions in chemical recovery processes. AN measurements are used to characterize an oil with respect to total concentration of strong and weak acids by means of nonaqueous potentiometric titration. The standard procedure (ASTM 2001) is designed to measure ANs in the range of 0.05 to 250 mg KOH/g oil. Stock-tank samples of crude oil usually have ANs that are at the low end of this range; strong acids are not encountered. Thus the sensitivity of the ASTM method is barely adequate for many samples of interest. According to the ASTM procedure, 20 g of oil should be used if AN is less than 1 mg KOH/g oil. Unfortunately, high-quality samples of crude oil are expensive to obtain and the quantity is very limited. Using 20 g for AN measurement would often preclude making any other measurements. The usefulness of AN data is greatly increased if it forms part of a matrix of information that includes, at a minimum, base number (BN), SARA fraction data, and information about asphaltene stability. There are few, if any, interfacial phenomena that correlate exclusively to AN. Basic constituents of an oil can also be assessed by nonaqueous potentiometric titration, but endpoints are often more difficult to detect because the organic bases that occur in crude oils can have a wide range of dissociation constants. More than a decade ago, Dubey and Doe (1993) published recommendations for improved base number measurements by adding a known amount of quinoline to force a readily detectible titration endpoint. Base numbers measured using spiked oil samples were significantly higher than those measured by the ASTM method and the higher base numbers were shown to correlate, together with AN for the same oils, with observations of wetting reversal on silica surfaces. A similar procedure was shown to improve the precision of AN titrations using stearic acid as the spiking agent for routine AN measurements (Monsterleet and Buckley 1996). Precipitated material was observed for some crude oils in the standard solvent (50% toluene, 49.5% isopropanol or IPA, and 0.5% water). Stearic acid and o-nitrophenol were used as spiking agents by Zheng and Powers (2003).

doi: 10.2118/99884-PA

SPE-99884-PA

SPE Journal

Country:

Asia > Vietnam > Long An Province > Tân An (0.24)
North America > United States > New Mexico (0.16)

Industry:

Energy > Oil & Gas > Upstream (1.00)
Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.97)

SPE Disciplines:

Reservoir Description and Dynamics > Improved and Enhanced Recovery (1.00)
Reservoir Description and Dynamics > Fluid Characterization > Phase behavior and PVT measurements (0.87)

Schulze, Lawrence J.H. (University of Houston)

Evaluation of International Safety Symbols

OnePetroJune, 2006

Abstract The use of pictograms has increased and their use can be found worldwide. Methods for assessing pictogram comprehension currently use ISO & ANSI standards. However, the rigor represented by these standards is not the same. Furthermore, these standards do not indicate how long an observer has to determine symbol recognition. Standard safety symbols were presented to engineering students to determine safety symbol comprehension/recognition. Symbols were presented to the participants on a display screen and the participants indicated the meaning of the symbol or indicated that they did not know. Participants' eye movements were tracked using an Applied Science Laboratories eye tracker. The results indicate that there are cultural differences among and between participants in the recognition and comprehension of safety symbols. The importance of these findings is that an 'international' safety symbol may not be 'international' at all. Introduction The term pictogram is a collective term used to describe both 'symbols'-considered to be abstract representations whose meaning must be 'learned'-and 'pictorials'-more representative pictures depicting messages (Mayer and Laux, 1989). Therefore, a safety pictogram is a diagrammatic representation using illustrations rather than words to convey a message. Easterby and Hakiel (1977) described the image content of a sign and the type of message being portrayed as one of the following three modes:Descriptive - The image identifies the hazard; for example, a flame suggests a fire hazard. Prescriptive - The image specifies some positive course of action to be taken in association with the hazard; for example, wear protective headgear. Proscriptive - Prohibition of some course of action; for example, do not smoke. A red circle with a slash is used extensively to convey that some activity or thing is forbidden. Peters (1984) suggested that pictograms can serve as 'instant reminders' of a hazard or an established message; have the potential to be interpreted more accurately and more quickly than words and they can sometimes be recognized and recalled far better than words. Jacobs (1975) and Collins and Lerner (1982) showed that pictograms can improve the legibility of a warning. Pictograms can be read more easily at a distance compared to textual information, although a distinction is made between abstract symbols and pictographs (described as more detailed and therefore likely to remain less legible). The United Kingdom Department of Trade and Industry (1995) found that pictograms or brief textual information might be better when undertaking familiar or routine tasks (although the opposite will apply for new or highly complex tasks). The advantage of symbols over word may not hold under all conditions for all symbols, however. Wolff and Wolgater (1993 & 1998) found that very few pictograms are universally understood. There is the potential for critical confusion (interpreting the opposite or often undesired meaning), especially in abstract pictograms that can create an additional safety hazard.

ASSE Professional Development Conference and Exposition

ASSE

ASSE-06-795

Country:

North America > United States (0.69)
Europe > United Kingdom (0.69)
Asia > Vietnam > Long An Province (0.24)

Genre: Research Report > New Finding (0.47)

Industry:

Health & Medicine (1.00)
Government > Regional Government > Europe Government > United Kingdom Government (0.34)

SPE Disciplines:

Health, Safety, Environment & Sustainability > Safety (1.00)
Health, Safety, Environment & Sustainability > Health > Ergonomics (0.49)
Data Science & Engineering Analytics > Information Management and Systems > Artificial intelligence (0.34)

Technology:

Information Technology > Artificial Intelligence > Cognitive Science (0.49)
Information Technology > Human Computer Interaction > Interfaces (0.36)

Holistic Environmental Assessment of Oil and Gas Field Development

Salter, E.R.E. (BP plc) | Ford, J.T. (Heriot-Watt University)

OnePetroMarch, 2002

Abstract Many organisations, such as the British Medical Association, European Oilfield Speciality Chemicals Association, the Royal Ministry of Petroleum and Energy (Norway) and Shell Expro, now recognise that a holistic approach is essential to assess total environmental risk. This paper presents a study that has developed a new life-of-field, goal orientated process of analysis called Holistic Environmental Assessment (HEA). HEA assesses the total environmental risk associated with a proposed oil and gas field development. It prioritises environmental risks and identifies cost effective strategies to reduce them. For the first time the process was applied to a real ‘case study’ field development programme, X Field in UKCS Block 22/12, to test its effectiveness. The application identified that HEA is a useful tool to help design eco-efficient and cost-effective oil and gas field developments. Furthermore, it was discovered that much of the information required by HEA could be obtained in a quick and userfriendly format. The authors propose that HEA would be effective as a software tool to analyse different environmental risk management systems. This would facilitate the identification of a system that steers an operator towards the triple bottom line of Sustainable Development. A guidance document detailing the HEA method and its application is available from the authors. Introduction Since 1998 the Department of Trade and Industry (DTI) has required that Environmental Statements (ES) are prepared for new offshore oil and gas projects in the UK that are expected to produce at least 500 tonnes of oil or 500,000 cubic metres of gas per day, and for the installation of offshore pipelines over 800 mm diameter and 40 km long. An ES does not have to include seismic surveying or field decommissioning, both elementary phases of field development. It is a recent development that operators in the UK have to assess the impact of seismic surveys on protected species and habitats under the Offshore Petroleum Activities (Conservation of Habitats) Regulations 2001. ESs do not follow a life -of-field approach to assess the total environmental risk from the whole process of exploring for and exploiting oil and gas that includes seismic survey, exploration wells, production facilities, large pipeline systems and decommissioning activities on and offshore. Nor do they prioritise environmental risks or evaluate the economic risk of managing that environmental risk. There is no tool available that can inform an operator of where best to invest capital to improve environmental and economic performance. An ES will focus on the environmental burden that a proposed development will impose. However, it is rare to find an ES that details an assessment of the contribution that a proposed activity makes, along with other activities in the area, to changing the state of the environment in the region or internationally. Life Cycle Analysis (LCA) was developed to assess the environmental loadings of a product, process or activity over its entire lifecycle. It was the first technique used in environmental analysis that adopted what was described as a holistic approach. It fails this approach by not assessing accidental emissions or environmental impacts other than those that are direct. Tools are required that encourage environmental parameters to be engineered into field design by establishing the costs and environmental benefits of action to companies and the regions in which they operate. This paper details the HEA process framework to demonstrate how total environmental risk may be appraised to facilitate oil and gas field planning, development, and decommissioning. Environmental Management Terminology An Environmental Manager will use two terms daily in the pursuit of excellent environmental performance:Environmental Aspects; and Environmental Impacts.

doi: 10.2118/73945-MS

SPE International Conference on Health, Safety and Environment in Oil and Gas Exploration and Production

SPE-73945-MS

air emission, asset and portfolio management, climate change, damage cost, environmental aspect, environmental damage, environmental impact, environmental pollution, environmental risk, field development, HEA, hea process, holistic environmental assessment, identification, information, operator, probability, spe 73945, Upstream Oil & Gas

Country:

Europe > United Kingdom (1.00)
North America > United States (0.93)
Asia > Middle East > Israel > Mediterranean Sea (0.34)
Asia > Vietnam > Long An Province (0.24)

Geophysics: Geophysics > Seismic Surveying (1.00)

Industry: Energy > Oil & Gas > Upstream (1.00)

SPE Disciplines:

Management > Asset and Portfolio Management > Field development optimization and planning (1.00)
Health, Safety, Environment & Sustainability > Environment > Climate change (1.00)
Health, Safety, Environment & Sustainability > Environment > Air emissions (0.93)
Health, Safety, Environment & Sustainability > Sustainability/Social Responsibility > Sustainable development (0.88)

Technology: Information Technology > Software (0.34)

Techniques for Determining In-Situ Stress Direction and Magnitudes

Bloch, M. (Petrobras S.A.) | Siqueira, C.A.M. (Unicamp) | Ferreira, F.H. (Petrobras S.A.) | Conceicao, J.C.J. (Petrobras S.A.)

OnePetroAugust, 1997

Abstract Knowledge of the in-situ stress field is highly beneficial when designing the drilling direction of horizontal and deviated wells or programming a massive hydraulic fracturing. According to the available technology it is well accepted that reliable in-situ stress orientation and magnitude determination must be based upon the utilization of several techniques, instead of only one. Field examples of Petrobras effort in determining in-situ stresses with the An elastic Strain Recovery Test (ASRT), breakout analysis and microfracturing is shown in this paper. Strain relief techniques like the ASRT are very economical since they do not require to occupy the drill hole for testing, although obtaining oriented cores may not be in the drilling original schedule. While reliable data can be obtained with the ASRT for the stress orientation, the same is not true for the stress magnitudes. Breakout analysis has proved to be a very powerful indicator of the horizontal stress direction since it is caused exactly by the in-situ stress contrast. The issue here is to ascertain that the detected borehole elongation has enough evidences of been caused by breakout. Hydraulic microfracturing, when including poroelastic effects, seems to be the best option for determining the minimum horizontal in-situ stress magnitude. Introduction Measuring in-situ stress is still a challenging task to the oil industry in 1997. Due to the lack of a fully reliable method capable to work on a large variety of rock types, stress field and harsh deep downhole conditions, operators and service companies usually apply different methods to compare their result and compute a statistical average for the in-situ stress direction and magnitude. They can be divided into core-based methods, borehole-based techniques, near-wellbore techniques and regional geologic indicators. The list of techniques for determining in-situ stress is quite long:An elastic strain recovery test (ASRT); Axial point load test; Borehole breakout analysis; Borehole deformation; Borehole imaging; Circumferential velocity anisotropy (CVA); Differential strain curve analysis (DSCA); Direct observation of overcored open-hole microfractures; Directional gamma ray logging; Drilling induced fractures in core; Earth tilt surveys; Leak-off inversion technique; Microfracture pressure analysis; Microseismic logging; Overcoring of archived core; Petrographic examination of microcracks; World stress mapping. The an elastic strain recovery technique is based on the core strain relief after coring. Individual sand grains become stressed during burial and lithification of the sedimentary materials, resulting in compression and distortion of the grains. The stored energy within the grain may vary in different directions, depending on the amount of stress that was applied in each orientation. When a rock stratum is cored, the sand grain attempt to expand elastically as soon as original stresses are relieved, but they are held back by cement bonds. Many of these cement bonds will eventually be broken, forming a microcrack population preferentially aligned with the stress field. Microcracks will have then observable effects on petrophysical properties in a homogeneous isotropic material. Combination of core-based techniques with breakouts may be the only way to obtain specific stress estimates when rock conditions constrain the use of drill hole testing methods.

doi: 10.2118/39075-MS

Latin American and Caribbean Petroleum Engineering Conference

SPE-39075-MS

Country:

North America (1.00)
Europe (0.94)
South America > Brazil > Rio de Janeiro (0.29)
Asia > Vietnam > Long An Province (0.24)

Geophysics: Geophysics > Seismic Surveying > Borehole Seismic Surveying (1.00)

Industry: Energy > Oil & Gas > Upstream (1.00)

Oilfield Places:

South America > Brazil > Rio de Janeiro > South Atlantic Ocean > Campos Basin > Macae Formation (0.99)
South America > Brazil > Rio de Janeiro > South Atlantic Ocean > Campos Basin > Garoupa Cluster > Garoupa Field (0.99)
South America > Brazil > Rio Grande do Norte > South Atlantic Ocean > Potiguar Basin (0.99)
(13 more...)

SPE Disciplines: Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)

Technology: Information Technology (0.46)

Mattar, L. (T. Fekete & Associates Consultants Ltd.) | Hawkes, R.V. (T. Fekete & Associates Consultants Ltd.)

Start Of The Semi-Log Straight Line In Buildup Analysis

OnePetroJune, 1984

Abstract If the duration of the flow period preceding a buildup test is not sufficiently long an apparent semi-log straight line may still be seen both on a type curve match and a Horner plot. The analysis of this semi-log straight line results in the wrong value of permeability but a reasonable p ∗. A longer shut-in does not correct the problem unless it is preceded by a longer flow period. The use of "equivalent time" to account for the short flow period introduces problems of its own. Introduction In most oil or gas well test interpretations, it is important to determine if the data obtained are such that a meaningful semi-log analysis can be performed. In recent years, this has been done by "typecurve matching" the data and noting, from the typecurve, the approximate start of the semi-log data. Once this has been determined, the data following that point are analyzed by selecting a semi-logarithmic straight line, the slope of which can be used to determine the transmissibility of the reservoir. The curves used for "typecurve matching" are, generally, derived from drawdown tests but they can be used for buildup tests if the data are first desuperposed. When rigorous desuperposition can not be done, an approximate method is often used, which is usually adequate for determining the approximate start of the semi-log straight line for use with Horner or similar plots. In a large number of buildup tests recently analyzed by the authors, it was observed that, often, two tests on the same well gave significantly different results of interpretation. The method of interpretation was the same for both tests, namely: from the typecurve match, determine the approximate start of the semi-log straight line, and then use that in the Horner analysis. Both sets of desuperposed data showed the presence of an acceptable semi-log straight line. The principal difference between the two sets of tests was the duration of the flow period - one was significantly longer than the other. Why were the interpretations so different? and which one is the correct one? Model In order to resolve the problem a theoretical investigation was undertaken. Pressure buildup datawere simulated for flow periods of varying durations and these synthetic pressures were then analyzed by the standard methods. The reservoir model selected for this presentation is that of an infinite, homogeneous reservoir with a vertically fractured well - the fracture has an infinite conductivity, and wellbore storage is considered to be negligible. Such a model fits a very large number of wells which have been hydraulically fractured. The solution - in dimensionless terms - for this model was presented by Gringarten, Ramey and Raghavan in 1972 (ref 1) and is shown in "typecurve matching" format in Figure 1. This solution applies to a constant rate drawdown but it can be used, with the principle of superposition, to derive buildup information for any shut-in time Δt, following a flow period of duration t. (ref 2) Equation (1) (Available In Full Paper)