Showing papers in "Journal of Petroleum Technology in 1986"
TL;DR: The most accurate results are obtained when native-state, cleaned, and restored-state cores are run with native crude oil and brine at reservoir temperature and pressure as discussed by the authors, and they provide cores that have the same wettability as the reservoir.
Abstract: Wettability is a major factor controlling the location, flow and distribution of fluids in a reservoir. The wettability of a core will affect almost all types of core analyses, including capillary pressure, relative permeability, waterflood behavior, electrical properties, and simulated tertiary recovery. The most accurate results are obtained when native- or restored-state cores are run with native crude oil and brine at reservoir temperature and pressure. Such conditions provide cores that have the same wettability as the reservoir. The wettability of originally water-wet reservoir rock can be altered by the adsorption of polar compounds and/or the deposition of organic material that was originally in the crude oil. The degree of alteration is determined by the interaction of the oil constituents, the mineral surface, and the brine chemistry. The procedures for obtaining native-state, cleaned, and restored-state cores are discussed, as well as the effects of coring, preservation, and experimental conditional conditions on wettability. Also reviewed are methods for artificially controlling the wettability during laboratory experiments.
920 citations
TL;DR: In this article, a methode permet de determiner si a carotte is a mouillabilite mixte, or not, is proposed, which permits to determine whether a mixture of carsets is a mixte.
Abstract: Article de synthese sur les limites et les avantages des methodes de mesure de la mouillabilite. Ces methodes sont quantitatives: methode Amott, methode du Bureau des Mines des Etats-Unis (USBM), methode de l'angle de contact ou qualitatives: imbibition, examen microscopique, flottation, ecoulement vitreux, courbes de permeabilite relative, courbes de pression capillaire, capillarimetrie, pression capillaire de deplacement, relations permeabilite/saturation et diagraphie de reservoir. Les methodes de RMN et d'adsorption de colorant destinees a mesurer la mouillabilite fractionnelle sont egalement discutees. Enfin l'auteur propose une methode qui permet de determiner si une carotte a une mouillabilite mixte
759 citations
TL;DR: In this article, the authors examined the effects of wettability on the Archie saturation exponent and the formation factor, which are determined experimentally in cores, and concluded that the effect of clays in a core is significant.
Abstract: This paper examines the effects of wettability on the Archie saturation exponent and the formation factor, which are determined experimentally in cores. These parameters are important in the investigation of the hydrocarbon saturation of a formation by use of resistivity data obtained from well logging. The Archie saturation exponent, n, typically has a value of about 2 in water-wet formations and cleaned cores, while in native-state, non-water-wet cores and formations it is generally larger than 2. In uniformly oil-wet cores with low brine saturations, n can reach values of 10 or more. The exponent is higher in oil-wet cores at low saturations because a portion of the brine is trapped or isolated in dendritic fingers where it is unable to contribute to electrical conductivity. If a cleaned water-wet core is used to measure n and the reservoir is actually oil-wet, interstitial water will be underestimated during logging. No definite conclusions can be drawn about the effects of wettability on the formation factor. However, the wettability of clays in a core is likely to affect this parameter.
217 citations
TL;DR: In this paper, X-ray computerized tomography (CT) and nuclear magnetic resonance (NMR) imaging have become the premier modalities of medical radiology, and both of these imaging techniques also promise to be useful tools in petrophysics and reservoir engineering.
Abstract: In little more than a decade, X-ray computerized tomography (CT) and nuclear magnetic resonance (NMR) imaging have become the premier modalities of medical radiology. Both of these imaging techniques also promise to be useful tools in petrophysics and reservoir engineering, because CT and NMR can nondestructively image a host of physical and chemical properties of porous rocks and multiple fluid phases contained within their pores. The images are taken within seconds to minutes, at reservoir temperatures and pressures, with spatial resolution on the millimeter and submillimeter level. The physical properties imaged by the two techniques are complementary. CT images bulk density and effective atomic number. NMR images the nuclide concentration, M/sub 0/, of a variety of nuclei (/sup 1/H, /sup 19/F, /sup 23/Na, /sup 31/P, etc.), their longitudinal and transverse relaxation-time curves (t/sub 1/ and t/sub 2/), and their chemical shift spectra. In rocks, CT images both rock matrix and pore fluids, while NMR images only mobile fluids and the interactions of these mobile fluids with the confining surfaces of the pores.
128 citations
TL;DR: A broad overview of the nature of formation damage problems, how they occur during various oilfield operations, and their effects on well productivity is provided in this paper, where the use of treating fluid filtration, clean work strings (pipe), and inhibited fluids has been shown to be important in the control of formation damages during well treatment.
Abstract: Almost every field operation is a potential source of damage to well productivity. This paper provides a broad overview of the nature of formation damage problems, how they occur during various oilfield operations, and their effects on well productivity. Diagnosis of formation damage problems has led to the conclusion that formation damage is usually associated with either the movement and bridging of fine solids or chemical reactions and thermodynamic considerations. The fine solids may be introduced from wellbore fluids or generated in situ by the interaction of invading fluids with rock minerals or formation fluids. Control of formation damage requires proper design of treating fluids for chemical compatability and strict quality control of fluid physical and chemical properties during treatment. The use of treating fluid filtration, clean work strings (pipe), and inhibited fluids has been shown to be important in the control of formation damage during well treatment.
110 citations
TL;DR: Miscible displacement has been developed as a successful EOR process in the past 25 years as discussed by the authors, and two types of miscible displacement exist: first contact and multicontact, and an understanding of the definition of miscibility and how injected fluids react with reservoir fluids is necessary to understand these processes
Abstract: Miscible displacement has been developed as a successful EOR process in the past 25 years. Two types of miscible displacement exist: first-contact and multicontact miscible displacement. An understanding of the definition of miscibility and how injected fluids react with reservoir fluids is necessary to understand these processes.
75 citations
TL;DR: A summary of the present status in numerical modeling of geothermal systems, emphasizing recent developments, is given in this paper, where various modeling tasks, including natural-state, exploitation, injection, multi-component and subsidence modeling, are illustrated with geothermal field examples.
Abstract: During the last decade the use of numerical modeling for geothermal resource evaluation has grown significantly, and new modeling approaches have been developed. In this paper we present a summary of the present status in numerical modeling of geothermal systems, emphasizing recent developments. Different modeling approaches are described and their applicability discussed. The various modeling tasks, including natural-state, exploitation, injection, multi-component and subsidence modeling, are illustrated with geothermal field examples. 99 refs., 14 figs.
54 citations
TL;DR: In this paper, a carefully planned well conditioning and testing program is used to adjust FVF's and gas/oil ratios (GOR's) for surface separator conditions.
Abstract: Fluid samples must be taken early in the life of a reservoir to obtain samples truly representative of the reservoir fluid. They should be taken only after a carefully planned well conditioning and testing program. When the PVT data obtained from these samples are used, care should be taken to adjust FVF's and gas/oil ratios (GOR's) for surface separator conditions.
49 citations
TL;DR: The Second Comparative Solution Project (SSP) as mentioned in this paper is a three-phase coning problem that can be described as a radial cross section with one central producing well, where the oil and water densities are nearly equal, so the oil/water capillary transition zone extends high up into the oil column.
Abstract: Eleven companies participated in the Second Comparative Solution Project. The problem to be solved is a three-phase coning problem that can be described as a radial cross section with one central producing well. The oil and water densities are nearly equal, so the oil/water capillary transition zone extends high up into the oil column. Wide variations in rates occur, and the solution GOR is unusually high for oil with such high density. These problem characteristics make the problem difficult to solve, thus increasing its value as a test of simulation techniques. Various aspects of the numberical solutions obtained are compared in this paper. In general, the solutions agree reasonably well.
46 citations
TL;DR: Champlin Petroleum Co.'s pilot test of the CO/sub 2/ immiscible-drive oil recovery process has been in continuous operation for 50 months in the Wilmington field, Tar zone, Fault Block III Unit reservoir as discussed by the authors.
Abstract: Champlin Petroleum Co.'s pilot test of the CO/sub 2/ immiscible-drive oil recovery process has been in continuous operation for 50 months in the Wilmington field, Tar zone, Fault Block III Unit reservoir. First CO/sub 2/ injection was in March 1981. The pilot, containing 1,700 acre-ft (2.1 x 10/sup 6/ m/sup 3/) includes four injection wells and three producers. The reservoir is an unconsolidated sandstone at 2,500 ft (762 m) that contained 920 bbl/acre-ft (0.12 m/sup 3//m/sup 3/) of 14/sup 0/API (0.97-g/cm/sup 3/) crude oil at the start of the CO/sub 2/ pilot. This is the first test of immiscible CO/sub 2/ tertiary oil recovery in a late-life waterflood reservoir. Cumulative water injection before start of the CO/sub 2/ pilot was three PV's. Through May 1, 1985, 2.1 Bcf (60 x 10/sup 6/ m/sup 3/) of produced and purchased CO/sub 2/ had been injected intermittently with water. Cumulative purchased CO/sub 2/ through May 1, 1985, was 1.5 Bcf (42.5 x 10/sup 6/ m/sup 3/). Each of the three producing wells has shown stimulated oil response with production rates increasing an average of seven-fold. One producing well, converted from a former water-injection well, produced 100% water for 5 months after first CO/submore » 2/ injection. The well has since steadily increased in production to over 40 B/D (6.4 m/sup 3//d) of oil. All produced oil is considered incremental oil since the pre-CO/sub 2/-flood oil rates were essentially at the economic limit and the wells would soon have been plugged and abandoned.« less
39 citations
TL;DR: In this article, a simulation en laboratoire du transfert de masse entre un gaz d'injection and l'huile d'une roche magasin is presented.
Abstract: Etude par simulation en laboratoire du transfert de masse entre un gaz d'injection et l'huile d'une roche magasin. Le dispositif de simulation est decrit. L'equation d'etat de Schmidt-Wenzel est utilisee pour prevoir, avec plus de precision, la densite de la phase liquide et des correlations sont proposees afin de determiner le volume d'huile stocke dans la roche magasin. Les parametres d'interaction hydrocarbures/CH 4 N 2 ou CO 2 sont calcules en utilisant l'equation Peng-Robinson. La simulation du comportement des phases est appliquee a la prevision des conditions de misabilite de l'huile de stockage ou de l'huile d'une roche magasin lors de l'injection de CO 2 ou de N 2
TL;DR: In this paper, a wide range of stimulation treatments that can yield impressive production increases in many wells if properly applied are classified into two categories: matrix acidizing and fracture acidizing.
Abstract: Acidizing involves a wide range of stimulation treatments that can yield impressive production increases in many wells if properly applied. Acidizing treatments are divided into two categories: matrix acidizing and fracture acidizing. To use either treatment properly, an understanding is required of what the treatments do and what is necessary to stimulate the well.
TL;DR: In this article, a study of 90 wells perforated with the tubing-conveyed perforating system showed a correlation between underbalanced pressure and formation permeability that can be used to achieve clean perforations.
Abstract: A study of 90 wells perforated with the tubing-conveyed perforating system showed a correlation between underbalanced pressure and formation permeability that can be used to achieve clean perforations. The data, from gas and oil producers in clean sandstones, are from wells that were perforated, tested, acidized, and retested. There is a clear minimum underbalance line separating the data sets of wells that had clean perforations (unassisted by acidizing) from those wells that showed a significant productivity increase after acidizing. The study includes data from oil and gas wells in the Gulf of Mexico, Lousiana (Tuscaloosa trend), New Mexico (Morrow sandstone), Rocky Mountain overthrust, and Alberta, Canada.
TL;DR: In this paper, the authors presented five-, seven-, and nine-spot pattern steamflood simulation results with parallel and diagonal grids and five-and nine-point difference schemes.
Abstract: This paper presents five-, seven-, and nine-spot pattern steamflood simulation results with parallel and diagonal grids and five- and nine-point difference schemes The effects of difference scheme and grid orientation are examined in a two-dimensional (2D) (vertical) cross section Effects of different types of grid spacings in cyclic steam simulation are discussed Sample problem data sets are roughly representative of a California deposit and a more viscous Alberta crude Various seven-spot grids (neither parallel nor diagonal) and nonuniform five-/nine-spot grids pose unique challenges to both difference schemes, with interesting results The conclusions emphasize superiority of the nine-point difference scheme and the pitfalls of certain problem/grid/difference-scheme combinations in pattern steamflood simulation Nine-point transmissibility alterations are used that allow rigorous use of 1/8 five-/nine-spot patterns as opposed to 1/2 or 1/4 elements with either parallel or diagonal grids This is important because of significantly reduced cost compared with 1/4- or 1/2-pattern elements Subject to certain conditions, the paper presents a simple procedure to calculate well-productivity indices for uniform or nonuniform grids, cross sections, or any of the three patterns, and either of the two difference schemes
TL;DR: In this article, the authors provided the reservoir simulation engineer with a viable geological and petrophysical model of the Shuaiba reservoir to aid in understanding observed phenomena, which is speculated that early accumulation of oil played a major role in preserving the high porosity and greater crestal reservoir thickness by inhibiting diagenetic processes.
Abstract: The Yibal oil field in west central Oman is a large dome created by deep-seated salt movement. The maximum oil column is 370 ft (112.8 m) and the productive area is about 4.3 x 6.2 mile (7 x 10 km). The structure is complicated by extensive tensional faulting. The main oil accumulation is in the Shuaiba chalk overlain disconformably by the Nahr Umr shale. The Shuaiba reservoir is in pressure communication with the underlying Kharaib formation. It is speculated that early accumulation of oil played a major role in preserving the high porosity and greater crestal reservoir thickness by inhibiting diagenetic processes. This field study provided the reservoir simulation engineer with a viable geological and petrophysical model of the Shuaiba reservoir to aid in understanding observed phenomena.
Journal Article•
TL;DR: In this paper, des mecanismes de formation and precipitation de silice hydratee provenant des reactions entre largile and l'acide fluorhydrique.
Abstract: Etude des mecanismes de formation et de precipitation de silice hydratee provenant des reactions entre l'argile et l'acide fluorhydrique. La precipitation de silice hydratre entraine une degradation de la roche magasin avant que l'acide fluorhydrique ne soit recuperee. L'auteur etudie les moyens d'inhiber cet endommagement
TL;DR: In this paper, the authors used a computer model to predict the future production profile and assessed the model output uncertainty with a series of calculations with input values obtained by sampling the input distributions.
Abstract: Advanced statistical techniques of risk analysis are applied to the valuation of proposed supplemental and EOR projects to assess the need for additional technical data and to improve the decision-making process. Financial evaluation must consider the technical complexities of the recovery process. To rely solely on historical production performance to assess the value of a given producing property is not practical. More reliance must be placed on the recovery-process models for reasonable projections of production profiles that will be the basis of financial evaluations. Uncertainties about the basic reservoir parameters in prediction models create uncertainties in the resulting financial evaluations. Also, there are often substantial uncertainties in the financial factors used. Degree of uncertainty in a financial valuation is an important to the decision-making process as the estimate of a project's value. This paper presents techniques for determining the degree of uncertainty in a project valuation and which parameters contribute most to this uncertainty. The authors used a computer model to predict the future production profile. Uncertainty in model input is addressed by assigning appropriate distributions to input parameters. Model output uncertainty is assessed with a series of calculations with input values obtained by sampling the input distributions. The newmore » aspect of this study is the use of the recently developed latin hypercube sampling (LHS). LHS, more efficient than simple Monte Carlo sampling, readily allows important correlations between the input parameters considered, and permits the use of more sophisticated and appropriate recovery process models.« less
TL;DR: In this paper, the results of six microfracturing experiments in a gas well in south Texas were described, which consisted of pumping very small volumes of drilling mud at very low rates (3 to 30 gal/min).
Abstract: This paper describes the results of six microfracturing experiments in a gas well in south Texas. The experiments were conducted in open hole and during the drilling operations. Microfracturing consisted of pumping very small volumes of drilling mud (tens of gallons) at very low rates (3 to 30 gal/min (189 to 1892 x 10 /sup -6/ M/sup 3//s)). Three of these microfractures extended below the bottom of the open hole and were cored out. Created fracture orientation was obtained from the fractures observed in the oriented core. Several instantaneous shut-in pressures recorded in each zone showed variations of about 200 to 300 psi (1.4 to 2.1 MPa). This magnitude change is attributable to heterogeneity of the rock. Measured values of instantaneous shut-in pressure (ISIP) did not show any trend with lithology (shale or sandstone), mechanical properties, or tensile strength.
TL;DR: In this article, the authors discuss how the engineering simulator for drilling (ESD) can be used to make economic decisions that can guide management in the selection of drilling contractors and other drilling related services.
Abstract: This paper discusses how the engineering simulator for drilling (ESD) can be used to make economic decisions that can guide management in the selection of drilling contractors and other drilling-related services. The simulation concept is described with details of the time- and cost-generating methods used by the ESD and a presentation of three examples that show the analytical capabilities of the simulator. The first example is an analysis of two diverse drilling well plans. The second example demonstrates how the ESD provides a rational basis from which a mud-company selection can be made. In the last example, the engineering simulator is used to measure the performance of two different rigs quantitatively. This example shows how rigs can be selected with the simulator and how the ESD provides the drilling engineer with the ability to make more optimum choices of drilling designs and cost estimates. The ESD also provides management with a yardstick for selecting between various proposed well plans and various contractors by defining accurately the factors that affect the bottom line.
Journal Article•
TL;DR: In this paper, the most important parameters controlling this process are the physical properties of the formation (and the pore fluid) being drilled, which are largely unknown at the time of drilling.
Abstract: Measurement while drilling (MWD) is the downhole measurement of important parameters and (in most cases) the simultaneous transmission of those measurements to the surface while drilling. In the past, hole-making and formation evaluation processes have been accomplished with different technologies, separated in time. Drilling (hole-making) is a complicated technological process with many uncertainties. Ignorance of what is taking place downhole during this process has caused it to be viewed more as an art than as a science. The most important parameters controlling this process are the physical properties of the formation (and the pore fluid) being drilled, which are largely unknown at the time of drilling. The big mistakes that involve the loss of well control (blowouts) are well known. The many ''small'' mistakes (kicks, lost circulation, stuck pipe, lost cones, twistoffs, etc.) are not so well known, but cost considerable time and money. The conventional (wireline) formation evaluation process, while very important to the geologist, the petrophysicist, and the reservoir engineer, is also very expensive in terms of rig time and trouble cost.
TL;DR: In this paper, surface processing considerations for CO/sub 2/EOR projects are described in light of the unique properties of CO 2, including water content, hydrate formation conditions, solvent properties, corrosion properties, and acid properties.
Abstract: This review paper describes surface processing considerations for CO/sub 2/ EOR projects in light of the unique properties of CO/sub 2/. The effects of CO/sub 2/ density, water content, hydrate formation conditions, solvent properties, corrosion properties, and acid properties are described, along with they latest advances in CO/sub 2/ purification technology. It is intended to give reservoir engineers, geologists, and process engineers working in associated areas a better understanding of the variety of factors in processing CO/sub 2/ for EOR.
TL;DR: In case of primary control loss resulting from a sudden increase of formation pressure or lost circulation, it becomes necessary to seal off the well by some other means to prevent an uncontrollable flow, or blowout, of formation fluids.
Abstract: In normal drilling operations, the primary well control is the hydrostatic pressure exerted by the drilling fluid in the well. This pressure can be adjusted to the specific conditions by a variation in the fluid density. Proper well planning requires the hydrostatic head of the drilling fluid to overbalance the formation pressure by a certain safety margin. In case of primary control loss resulting from a sudden increase of formation pressure or lost circulation, it becomes necessary to seal off the well by some other means to prevent an uncontrollable flow, or blowout, of formation fluids. The equipment that performs this secondary control function is the blowout preventer (BOP). BOP's are mounted directly to the wellhead in combinations called the BOP stack. Such a stack will normally contain several of the two basic BOP types: ram and annular. In special situations, a third BOP type-the rotating BOP-can also be used in combination with rams and annulars.
TL;DR: In this article, a triaxial system for applying tensile stress to rock cores under confining pressure at strain rates characteristic of fracturing operations was developed, where strain gauges mounted on each core were used with a servo-controlled press to apply strain at a linear rate between 10/sup -4/ and 10/Sup -6/ seconds /sup -1/
Abstract: The importance of reservoir rock plasticity in fracturing operations has been investigated by laboratory experiments and field results. A Lagrangian formulation for crack propagation provided the basis for the laboratory experiments. A simple crack propagation experiment showed that plasticity effects can be observed and that the importance of plasticity depends on the relative magnitudes of surface energy and energy dissipated in plastic deformation of a reservoir rock. The latter can be evaluated by laboratory measurements of a plasticity coefficient, ..cap alpha.., which comes out of the Lagrangian analysis. To measure ..cap alpha.., the authors developed a triaxial system for applying tensile stress to rock cores under confining pressure at strain rates characteristic of fracturing operations. Strain gauges mounted on each core were used with a servo-controlled press to apply strain at a linear rate between 10/sup -4/ and 10/sup -6/ seconds /sup -1/ and to obtain stress/strain data to the point of tensile failure. To distinguish between plasticity and nonlinear elastic phenomena, the authors also obtained strain hysteresis data.
TL;DR: In this paper, a technical review of the materials selection process for sour service is provided, highlighting H/sub 2/S corrosion processes that occur on high-strength steels and corrosion-resistant alloys.
Abstract: This paper provides a technical review of the materials selection process for sour service. It highlights H/sub 2/S corrosion processes that occur on high-strength steels and corrosion-resistant alloys. In addition, procedures to perform materials evaluation and selection to minimize the deleterious effects of H/sub 2/S are discussed.
TL;DR: The potential for EOR by miscible processes in known U.S. reservoirs was evaluated by the National Petroleum Council (NPC) in 1982 as mentioned in this paper, and the potential EOR for miscible flooding was estimated between 2.0 and 8.5 x 10/sup 9/ bbl (0.32 and 10/Sup 9/ m/sup 3/) over the range of prices and technologies considered.
Abstract: In March 1982, the Secretary of Energy requested the National Petroleum Council (NPC) to evaluate the EOR potential of the U.S. The NPC Committee on EOR was formed to fulfill this request. Under this committee, a coordinating subcommittee and four working task groups were selected to perform the study. This paper describes the work of the Miscible Displacement Task Group and reports their findings and conclusions on the potential for EOR by miscible processes in known U.S. reservoirs. In conjunction with the coordinating subcommittee and the other task groups, the Miscible Displacement Task Group helped upgrade the DOE reservoir data base into the most comprehensive data base available to date on U.S. reservoirs. A miscible process and economic screening model prepared under contract for the DOE was analyzed, modified, and calibrated by the Miscible Displacement Task Group for this study. With physical screening parameters, the Miscible Displacement Task Group selected reservoirs susceptible to miscible processes from the data base, and then processed them with the NPC model to estimate tertiary oil recovery. Sensitivity to oil prices and rate of return (ROR) were investigated, and the results were combined with the results from the other process task groups (thermal and chemical) more » to reach an overall assessment of the EOR potential in the U.S. The potential EOR for miscible flooding is estimated to vary between 2.0 x 10/sup 9/ and 8.5 x 10/sup 9/ bbl (0.32 x 10/sup 9/ and 1.4 x 10/sup 9/ m/sup 3/) over the range of prices and technologies considered. Peak rate varies from 200 x 10/sup 3/ to 980 x 10/sup 3/ B/D (32 x 10/sup 3/ to 156 x 10/sup 3/ m/sup 3//d) for the cases investigated. « less
TL;DR: In this article, the bottomhole assembly behavior and the bit/formation interactions are better understood, less expensive and safer holes can be drilled, and an understanding of the factors controlling hole angle and direction will contribute to hitting the drilling target more frequently.
Abstract: An understanding of the factors controlling hole angle and direction will contribute to hitting the drilling target more frequently. As the bottomhole assembly (BHA) behavior and the bit/formation interactions become better understood, less expensive and safer holes can be drilled.
TL;DR: In this paper, a 30-day water flooding test in which seawater was injected into an oil limestone reservoir located in the West Coast of the Persian Gulf was analyzed to detect the possible occurrence of fracture.
Abstract: A 30 day waterflooding test in which seawater was injected into an oil limestone reservoir located in the West Coast of the Persian Gulf was analyzed. The purpose of the analysis was to detect the possible occurrence of fracture. During testing, injection flow rates were recorded while tubing head pressures (THP) were maintained constant. Three different tubing head pressures were maintained during the test: initial THP of 990 psig, intermediate THP of 1240 psig, and final THP of 1490 psig. A radial flow analysis disclosed an increase in transmissibility for the intermediate and final stages of pumping. During these stages the bottomhole fluid pressures (BHP) exceeded the formation's minimum in situ stress as determined by an energy balance method. Both the increase in fluid transmissibility and the BHP rise above the minimum in situ stress indicated the occurrence of fracture. The expected fracture snape was obtained by using a 3-D hydraulic fracturing simulator.
TL;DR: The Drilling Advisor, a computer-based consultant whose goal is to provide advice about the cause and possible treatments of problems encountered during the drilling of wells, is discussed.
Abstract: This paper discusses the Drilling Advisor, a computer-based consultant whose goal is to provide advice about the cause and possible treatments of problems encountered during the drilling of wells. With the ''Expert Systems'' technique, a large amount of human knowledge can be represented as data structures in the system and efficiently used to make conclusions about the problem. Currently, it handles sticking and dragging of the drillstring in the open hole.