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ABSTRACT The Super High Temperature Geothermal Well Logging System as high as 450 C (842 degF) has been developed by Japan Petroleum Exploration Co. Ltd. The tools developed are temperature, Pressure and Spinner tools. These tools are so designed that all the down hole probes can be operated UP to 450 "C. Therefore, the following new technologies have been introduced. 1. The Logging Cable which consists of the magnesium oxide powder insulator. 2. The Cable head which can pass through the wire line lubricator of small diameter. 3. The Sealing mechanism between the cable head and pressure chamber which can be achieved by the use of special designed metal "O"" rings. 4. The super high temperature sensors which had been used in nuclear reactor technologies. 5. The heat insulation system for down hole electronics which consists of the combination of special designed dewar flask and heat sink materials. About a hundred times of field test were carried out from FY1983 to FY1984 in our geothermal wells where the maximum temperature was 240 "C to 340 "C (464 "F - 644 *F). The results of field tests shows that. This well logging system has sufficient reliability in such a severe environment of geothermal wells. As the second phase of Super High Temperature Logging System, slim hole Sonic Log, Latero Log, Bore hole fluid Sampler and Noise Log which detect a flash point and production zone were constructed in FY 1984, and will be put into the field test in FY1985.
- Energy > Renewable > Geothermal (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Energy > Power Industry > Utilities > Nuclear (0.55)
- Reservoir Description and Dynamics > Non-Traditional Resources > Geothermal resources (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (1.00)
ABSTRACT Complex carbonate sequences representative of Illinois and Michigan are evaluated through casing by combining data from the GST* Gamma Spectrometry service with sonic data for computations using a three-mineral model. Compressional travel time measurements (f) can be obtained through casing from digitized LSS* Long-Spaced Sonic data when cement bond exists. Log examples are presented to compare cased hole and openhole evaluations. INTRODUCTION Schlumberger's Gamma Spectrometry'serviceis designed to evaluate hydrocarbon reservoirs through casing. The GST service, a pulsed neutron tool, has been described previously. Water saturation (SW)is also obtained from the inelastic mode measurements of the spectral yields of carbon and oxygen.4 Computer processing is required for GST data interpretation because the interrelationship of the spectral yields is complex.
- North America > United States > Michigan (1.00)
- North America > United States > Illinois (0.73)
- North America > United States > Texas (0.70)
- Geology > Mineral (1.00)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.55)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Radioactivity Surveying > Radioactivity Acquisition (0.81)
- North America > United States > Michigan > Michigan Basin (0.99)
- North America > United States > Kentucky > Illinois Basin (0.99)
- North America > United States > Indiana > Illinois Basin (0.99)
- (25 more...)
ABSTRACT Oomoldic and vugular porosity is quite common in carbonate rocks. Sonic velocities in carbonates are often faster than predicted by the Wyllie Time Average equation. When using this model, sonic porosity is smaller than the actual porosity of the rock as shown by nuclear type measurements. The difference is currently referred to as the acoustic secondary porosity. In some cases it can be associated with the presence of oomoldic or vugular porosity in the rock. The present study is an evaluation of the effect of spherical pores on both acoustic velocities and electric conductivity. The effect of including spherical pores in a host medium is described by the Kuster-Toksoz model for acoustic properties and the Maxwell-Garnet model for electric conductivity. To develop an interpretation scheme we assume a typical behaviour for the primary host rock like the Wyllie relation for acoustic velocities and Archie's law for conductivity. The difference between these predictions and the actual measured values can be interpreted in terms of spherical porosity content. A computer processed level by level evaluation of the spherical porosity from acoustic velocities and conductivity logs was developed using this technique. Examples of the computation in two wells are presented and discussed. The results are very good in formations containing oomoldic porosity. The method is used to derive a variable cementation factor level by level, these results are compared with laboratory measured values.
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (1.00)
- Geology > Mineral (1.00)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- (26 more...)
Since the PDK-1OO timing cycle lasts 1000 microseconds, oxygen activation with its characteristic half-life of 7 seconds will appear as a background to the tool, giving the tool the capability of seeing water flow relative to the tool. As will be seen in one of the examples, by alternately shutting the well in and letting it flow, and by varying the logging rate, a detailed analysis of water flow in and around the borehole can be provided. Secondary Presentation Tracks 11 & 111 RBOR, Ratio Borehole, is the ratio of two successive gates very early in the decay of the short spaced detector. RBOR is usually presented with RIN, the Ratio of Inelastic counts of the short spaced to long spaced detectors. RIN is almost totally determined by borehole conditions due to the shallow depth of investigation of t e inelastic gamma rays. RBOR uses 3 capture gamma rays to view the borehole and is responsive to both borehole and formation conditions.
ABSTRACT Numerous algorithms have been proposed for the determination of true resistivity and depth of invasion, using data from resistivity or conductivity measuring tools, with differing depths of investigation. Very often these algorithms result from the "best fit" of the Tornado Charts for each combination of resistivity devices. A method for the generation of a general algorithm to solve for Rt and di using any combination of resistivity devices is developed. The method employs the solution of simultaneous equations in Rt and di. The first of this pair of equations assumes a step profile from Rxo and Rt after correction for borehole effects and is of the form:R (tool)= J(Rxo) + (1-J) (Rt)The second equation in the pair is a least squares curve fit of the respective pseudo-geometrical factors versus diameter of invasion di for the resistivity tool. This equation is a first order polynomial in log (di) of the form:J = a + b log (di), where a and b are constants Unique solutions for Rt and di may be obtained by employing pairs of simultaneous equations which are generated for each resistivity measurement of differing depth of investigation. An algorithm is developed for the Dual Laterolog - Rxo combination. A method of refining the algorithm that is generated initially is presented. This is achieved by dividing the depth being investigated by each device into several zones extending away from the borehole. A separate curve fit of the form J = a + b log (di) is made for each zone, for each corresponding resistivity device. Finally, a computer program which solves the algorithms for the DLL-Rxo combination is presented. The program executes on a HP-1000 computer system within the framework of the Gearhart developed operating system.
ABSTRACT The technique of deliverability analysis (Myers, et al., 1984) and McLeod's formulation (McLeod, 1983) are combined in this paper to examine the production rate from a gas well. It is shown that the production rate achieved in practice depends not only on the perforating parameters (shot density, tunnel length, and radius), but also depends substantially on the perforating practice (pressure, whether overbalanced or underbalanced, and type of borehole fluid). For a specific shot density, tunnel length and radius, the proper perforating pressure and fluid result in a production rate that is 150 to 250 percent of the rate that would result if less desirable practices were followed. The deliverability analysis is arranged to reveal the magnitude of the turbulent pressure loss through the compacted zones, and its relationship to the production rate. In addition, the magnitude of the turbulent loss is examined in relation to the laminar pressure loss, demonstrating that the turbulent loss tends to dominate not only the pressure drawdown at low perforating densities, but also the total pressure differential between the reservoir and the wellhead. This tendency may be accentuated by the perforating practice or by reducing the wellhead pressure. An example is shown in which the turbulent loss is 10 to 20 times greater than the corresponding laminar loss, in which case the compacted zones function as a near-wellbore choke. For limited perforating densities the deliverability analysis reveals that tubing having a reduced inside diameter may be used in place of a large diameter without a significant reduction of the production rate. As shown, the smaller tubing offers a reduced minimum production rate to prevent liquid loading, which is advantageous in the later period of a well's production phase.
Abstract When a low permeability well is hydraulically fractured, the test time required to acquire meaningful data and estimate both fracture and matrix parameters from a single test is often impractically long. Using today's linear flow analysis techniques, the test can be designed to achieve more reservoir information in less time. The general success of the stimulation, and the fracture half-length can be evaluated from two short tests, one before and one after the frac. It is necessary to obtain a pre-frac or other independent estimate of matrix permeability which can be combined with the linear flow data to yield an estimate of fracture parameters. By spending time on the pre-frac test, a greater amount of time can be saved by reducing the length of the post-frac portion of the test. Introduction This paper was written by and for the practising reservoir engineer. It collects and summarizes several important developments in pressure transient analysis and emphasizes how to practically apply them to the design and analysis of fractured well tests. It has been the authors' experience that quite often fractured wells are not tested properly, that the tests are long and expensive and fail to yield the desired practical evaluation of the success of the frac job. This is usually combined with the improper use of drawdown type curves and semi-log analysis. These well-known conventional techniques need to be supplemented with other techniques that have been specifically designed to account for the flow regimes found in fractured well tests. This paper presents three main ideas; the TandemRoot-T plot, and the delta-t-equivalent-radial and delta-t-equivalent-linear type curves. These are all powerful and useful ideas which have been previously published but do not yet seem to be used and applied widely in the industry. The use of these techniques is illustrated with a series of simple and practical examples. THE TANDEM-ROOT-T ANALYSIS METHOD Millheim and Cichowicz (1) originally demonstrated that for a buildup test dominated by linear flow, the pressure transient behavior could be modelled as: Equations (Available in full paper) This equation is presented in United States field units and uses pressure to represent gas potential Converted into metric units and using real gas pseudo-pressure, the equation reads as follows: Equations (Available in full paper) What this means is that, in a fractured gas well test where the pressure transient behavior can be adequately modelled by this equation, a plot of pseudo-pressure versus the tandem-root-t time function gives a straight line of slope (ml) which is directly proportional '[to the fracture half length (xf) and the square root of the formation permeability √k. The first step is to use a type curve to identify the linear flow dominated portion of the test and then draw a straight Line through that portion of the tandem-root-t plot. In their paper, which is a useful reference for engineers dealing with fractured wells, Lee and Holdiech (2) examined the theory and application of the Millheim and Cichowicz (N-C) method and proposed some further modifications.
Abstract Two factors determine oil recovery:displacement efficiency sweep efficiency For a miscible flood, high displacement efficiencies may be obtained. However, field performance (i.e. early sol vent breakthrough) shows that sweep efficiencies are generally low and may be attributed to the vastly different properties between the miscible and reservoir fluids. This paper discusses the improvement in performance that may be expected if horizontal injectors and producers are used in a miscible flood scheme. A numerical simulation model was used to quantify the increase in areal sweep efficiency that will result from using horizontal wells of various lengths at different mobility ratios in a 5-spot or staggered line-drive pattern. The study showed that the greatest percentage increase in areal sweep efficiency occurred at conditions with the most adverse mobility ratios. The increase in productivity at various wellbore lengths was also calculated and displayed in graphical form, showing that the productivity index may increase by nearly 5 times as the well bore length is extended. The improvement in flood front stability, effect on solvent dilution, and the potential uses of tilted horizontal wells in layered reservoirs, as well as some of the disadvantages and limitations involved with using horizontal wells have also been reviewed. Introduction There are two factors that determine the recovery from an oil reservoir: 1) displacement efficiency and 2) sweep efficiency. The use of miscible fluids to displace reservoir oil results in very high displacement efficiencies. reducing residual oil saturations to a small fraction of the original hydrocarbon pore volume. However, the differences in mobilities between the reservoir and the injected fluids has led to very poor sweep efficiencies, as evidenced by field performance. The more mobile solvent sweeps only a small portion of the project pattern before breaking through at the producing wells. It would seem that the generally poor sweep efficiencies that can be expected by using a fluid of such vastly different properties to displace oil is one of the prime factors preventing field scale projects from being technically and economically successful. The purpose of this paper is to investigate the improvement in areal sweep efficiency and general field performance that may be expected if horizontal wells, rather than vertical wells, are used in a miscible flood scheme. The concept of using horizontal wellbores, so-called 'horizontal wells', as a means of improving recovery and productivity dates back to the 1950's, but the most recent applications have generally been confined to the field of heavy oil. Little attention has been paid to the potential advantages to be gained by utilizing horizontal wellbores in miscible flooding schemes. This paper presents the results of a simulation study that was done to quantify the improvement in areal sweep efficiency that may be achieved by using horizontal wells instead of vertical wells. The potential uses of tilted horizontal wells, and the effect of horizontal wells on flood front stability and solvent dilution will also be discussed.
Abstract Carbon dioxide corrosion studies of oil-well portland cements were initiated using a new microsample technique to determine the effect of carbonic acid on portland cement slurry formulations and to develop a high carbonic acid corrosion-resistant cement for carbon dioxide Enhanced Oil Recovery applications. Earlier results from studies using two-inch API cement cubes showed carbonic acid had essentially no effect on cement after relative short test periods at elevated temperatures. Similar results with two-inch API cement cubes also were reported in recent literature. Because carbonic acid corrosion in cements was difficult to observe and measure using two-inch API cement cubes, a new microsample technique was developed. Use of this new technique, which represents an accelerated testing method, showed oil-well cements undergo a rapid deterioration in a wet carbon dioxide environment. Similar tests with two-inch cubes showed essentially no cement deterioration under the same conditions. Experimental details of this new microsample technique are discussed. Data relating cement strength loss and carbon dioxide penetration depths to cement type and slurry formulation are reviewed. included in the discussion is a new cementing formulation which shows significant promise as a high carbon dioxide- resistant, oil-well cement. Introduction Carbon dioxide Enhanced Oil Recovery applications seen a surge of activity in the last several years. Of the 40 projects that are estimated to be underway, 20 are in Texas and 7 are in the Gulf Coast region. while the remaining are distributed throughout the midwest and western states and Canada. Although the carbon dioxide Enhanced Oil Recovery process and carbon dioxide corrosion in oil and gas production are well documented in the literature, very little published information is available on carbonic acid corrosion in oil-well cements. However, the corrosion of cement structures by the leaching action of the carbon-dioxide-laden waters is well documented in the literature. It is well known that carbon-dioxide-laden water can reduce hydrated portland cement to a soft amorphous silica gel. The basic chemistry describing this process is as follows.CO2 + H2O ↔ H2CO3 ↔ H + HCO3 CaOH2 + H + HCO3 → CaCO3 C-S-H + H + HCO3 + CaCO3 + amorphous silica In Step (l), approximately 1% of the dissolved carbon dioxide reacts with water to form carbonic acid. As the carbon-dioxide-laden water diffuses into the cement matrix, the dissociated acid is free to react with the calcium hydroxide, which makes up 20% of the cement composition, and the hydrated calcium silicates (Steps (2) and (3), respectively). If the reaction would stop after the initial carbonation of the calcium hydroxide, the cementitious calcium carbonate formed would cause an increase in compressive strength. Although a strength increase is observed, as more carbon-dioxide-laden water invades the matrix, several new equilibria are established.(4) CO2 - H2O + CaCO3 ↔Ca(HCO3)2 (5) Ca(HCO3)2 + Ca(OH) 2 ↔ 2CaCO3 + H2O In the presence of excess carbon dioxide (Step 4), the calcium carbonate is converted to water-soluble calcium bicarbonate.
- Well Drilling > Casing and Cementing > Cement formulation (chemistry, properties) (1.00)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
Abstract The technical and economic feasibility of slant drilling Valhalla Doe Creek water injection wells from central pads was investigated and it was found to be a practical and economic alternative. Slant drilling commenced in September, 1984 and 23 wells have been completed. This paper includes ananalysis of the advantages and disadvantages of cluster dri11ing from central pads; a comparison of slant and directional drilling applicability; a discussion of project planning considerations; a review of drilling procedures, problems, and solutions; and an examination of drilling performance to date. Although some drilling problems were more complex than anticipated, slant drilling is believed to have an economic advantage over vertical drilling at Valhalla based On immediate tangible benefits. Introduction The technique of slant drilling, which is relatively new to Western Canada, differs from conventional directional drilling in that the well is spudded at an angle and then drilled toward the target. It offers the potential of greater horizontal displacements on shallow wells than conventional directional drilling and is well suited to "cluster" drilling: infil1 drilling from central pads. There has been some development of slant drilling in Canada during the past four years, primarily in shallow wells in the soft formations of eastern Alberta and western Saskatchewan. Petro-Canada''s Valhalla project is slant drilling''s first application to a waterflood scheme and represents the first use of slant drilling in the harder formations of north-western Alberta. The Valhalla field is located 42 km north-west of Grande Prairie, Alberta as shown in Figure L Conventional oil is produced from 43 wells in the Valhalla Doe Creek "C" Sand at an average vertical depth of 750 m. The pool was discovered in 1981 and is scheduled to go on waterflood in 1985. The waterflood project requires the drilling of 37 water injectors in an inverted five-spot pattern on 32 ha spacing. CLUSTER DRILLING FEASIBILITY The feasibility of directionally drilling the injection wells from central pads was investigaten. In the general case, four well s could be drilled from each surface pad. It was economically desirable to locate the surface pads on existing production well leases. Cluster drilling from central pads offers several advantages over individual vertical wells. The two modes of 32 ha Field development are compared in Figures 2 and 3 for vertical wells and cluster drilling respectively for a sample one square mile segment of the field. Figures 4 and 5 show a similar comparison for future 16 ha development. Cluster drilling provides the following benefits (refer to Figures 2,3,4 and 5):Surface land requirements are reduced. The total area to be leased and the number of leases required are decreased. All of the Valhalla pads are located on existing production well locations and in most cases, no additional land was required. There are resulting savings in initial lease payments and annual rent. Road and lease construction requirements are reduced. No new access roads were required and site preparation involved building minor extensions onto 12 locations rather than building 37 new drilling Sites.
- North America > Canada > Alberta > Saddle Hills County (0.27)
- North America > Canada > Alberta > Grande Prairie County No. 1 (0.27)
- North America > Canada > Alberta > Census Division No. 19 > County of Grande Prairie No. 1 > Grande Prairie (0.25)
- North America > Canada > Alberta > Western Canada Sedimentary Basin > Alberta Basin > Western Canada Sedimentary Basin > Greater Peace River High Basin > Valhalla Field > Kaskapau Formation > Aec Erl Valhalla 4-5-74-8 Well (0.99)
- North America > Canada > Alberta > Western Canada Sedimentary Basin > Alberta Basin > Deep Basin > Greater Peace River High Basin > Valhalla Field > Kaskapau Formation > Aec Erl Valhalla 4-5-74-8 Well (0.99)