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Collaborating Authors
Results
Abstract An extensive study of the weather conditions affecting the performance of A tightly controlled set of perforating charges has shown that a large amount of perforating charges has shown that a large amount of the variance of performance of charges is caused by tile storage conditions of both the charges and the detonating cord. The tests were run on a single lot of commercially available perforating charges that were made under extremely rigid quality control methods especially for the test. After initial testing of 15 of the charges to establish a level of variance, the charges were separated into lots and stored at. conditions simulating desert, sea coast, mountains, and arctic environments. Charges were stored in both unsealed and moisture resistant packaging. Charges were removed and fired at regular packaging. Charges were removed and fired at regular intervals to establish performance. Sections of detonating cord were also stored at the weather conditions in unsealed and moisture resistant packaging. The detonating cord was tested after one packaging. The detonating cord was tested after one year in storage. X-ray inspection was evaluated to determine if it could be used to spot potential problems in perforator performance. Long-term exposure to humidity and high temperature storage were proven to be detrimental to charge performance. Cyclic temperature storage was a factor performance. Cyclic temperature storage was a factor in the degradation of detonating cord. Introduction Over the last several years, an informal study has been made into formation damage occurring upon initial completion and continuing past the initial stimulation attempts. In this group of data, there were a significant number of cases where damage was confirmed after completion of the well and remained after a standard perforation breakdown attempt or small matrix acidizing perforation breakdown attempt or small matrix acidizing job. The source-of the damage was found to be perforation problems in several cases. Studies of perforation problems in several cases. Studies of misalignment of charges and poor quality charges have identified some major problems which could be spotted with perforating gun inspections. However, some wells had perforating gun inspections. However, some wells had productivity problems that appeared unrelated to productivity problems that appeared unrelated to misalignment. In these wells, full productivity was not reached, even though a high quality charge was used. A common denominator in several of these cases appeared to be the storage conditions of the charges and support equipment. The previous perforating performance studies generally focused on newer charges. When performance studies generally focused on newer charges. When a few older charges were tested, wide variations in penetration were often noted. It was the purpose of this penetration were often noted. It was the purpose of this study to determine what. effect the age of the charge and storage conditions had on the performance of the perforating charge. perforating charge. For this purpose, attempts were made to duplicate the storage conditions produced by several common weather conditions around the world. Discussion "Charge Description The charges used in the experiment were 20 gram, RDX, deep penetrating, powdered metal liner charges manufactured by a U.S. manufacturer. The charges were identical to a marketed charge, except that during manufacture the liner pressing pressures were derated very slightly so that a more uniformed penetration could be achieved. On receipt of the charges at the New Mexico Tech lest facility, 15 shots into a 8 ft tall, 60 diameter composition concrete target averaged 16.9 inches with a minimum of 15.3 inches to a maximum of 18.0 inches and a standard deviation of 0.87. The data on concrete compressive strength and charge test specifics for all the charge tests are contained in Table 1. For storage, charges were divided into lots selected at random from the stock of 240 charges. The charges were then retrieved from storage at one month, six months, nine months, twelve months and fifteen months, and samples of each storage lot were shot in concrete targets to evaluate any change in performance. Three charges from each storage condition were selected at each time interval. P. 247
Abstract A series of tests to describe the effect of numerous holes in casing on the mechanical crush resistance has been run in casing and in L-80 steel tube models. The tests were run with big holes and normal hole sizes for perforations in phasings of 0 degrees, 180 degrees, 120 degrees, 90 degrees, and 60 degrees. Shot density was varied in the model tubes from 4 to 36 shots per foot. The actual perforated casing was at 12 shots per foot. All of perforated casing was at 12 shots per foot. All of the perforated casing and tubing sections were compared to strength remaining in unperforated pipe of the same specimen. The tests were carried out in a compression machine under a controlled rate of loading with strain gauges attached at critical points along the plane of expected failure. The casing and tube plane of expected failure. The casing and tube specimens were loaded between steel platens. The data for the test are plotted in the form of load vs deflection. Strain gauge data are also presented. The information generated includes observations of the effect of entrance hole size, phasing (lateral hole separation), shot density (linear hole separation at a specific phasing), and effect of the position of the plane of perforations to the plane position of the plane of perforations to the plane of application of load. Introduction This project was implemented to establish how much lateral and axial crush resistance is lost after casing is perforated at shot densities from 4 to 36 shots/ft. The research used both 7 in. N-80 and P-110 casing perforated in cement targets and L-80 tubing machined to model the 7 in. casing on a 1 to 3.33 scale. The modeled parameters included scaled diameter, length, wall thickness, and perforation hole size. The casing was perforated with perforation hole size. The casing was perforated with jet charges. The holes in the tubing were drilled to model a 0.37 in. diameter hole, and 0.75 in. and 0.9 in. diameter big holes. An additional goal of the study was to determine the effect of perforation phasing on casing strength loss. The phasings used phasing on casing strength loss. The phasings used were the available commercial phasings of 0, 120, 90 and 60. The methods of applying load in these tests are intended to roughly simulate earth shifts such as plastic formation flow and stresses produced around salt domes and in unconsolidated formations. These tests do not attempt to model the effects of fluid pressure, either on unperforated or perforated sections. TEST PROCEDURE An upper test limit of 60,000 lb for the available Tinius-Olsen compression machine necessitated the use of tubes to model the casing, particularly in axial compression tests. A joint of L-80 grade tubing was cut and machined to provide the 11.5 in. long axial test pieces and the 6 in. long pieces for the lateral crush tests. L-80 grade pipe was selected for its similarity to N-80, one of the most commonly used grades, and because the requirements for the L-80 series pipe are more closely controlled than in N-80. Elongation tests on tensile specimens from L-80 tubing and N-80 and P-110 casing are shown along with the global stress vs strain curves of Figures 1 and 2. These tensile strength specimens were from the same joint of pipe as the perforated sections discussed later in the report. The compressional tests were worst possible case, point loading tests made by placing the model tubes or the actual sections of 7 in. casing between the steel platens of the Tinius Olsen compressional device and platens of the Tinius Olsen compressional device and deforming the casing by application of load at a rate equivalent to 0.00017 in./sec platen travel in unopposed loading or an application of 256 lbs/sec in an infinitely opposed condition. Application of the point-to-point loading in a steel-or-steel fashion does not take into account the effects of a concrete sheath or conforming borehole that would spread out the stress over a larger area. P. 215
Abstract One of the most recurrent problem in the oil-field is the removal of paraffin deposited on down-hole equipment and near-wellbore. Several field experiments were conducted to evaluate the effect of hot oiling for either the removal or redeposition of paraffin downhole. Laboratory work is presented paraffin downhole. Laboratory work is presented that suggests the use of hot solvents has the greatest potential benefit. Means of conventional field application are limited, and nonconventional means are discussed. Introduction The treatment of paraffin waxes within the oil-field is generally directed towards two goals:removal or inhibition of deposits within the formation or on the formation face and the removal or inhibition of paraffin from surface and downhole tubulars and equipment, which impedes the flow of produced fluids. The most common forms of treatment can be divided into three categories: thermal, chemical, or mechanical, with some methods using a combination of these means. Paraffin Description Paraffin Description Paraffins are composed of carbon and hydrogen atoms with formulas of C18H38 to C70H172. Although usually straight chain, they can also be branched. Paraffin is commonly associated with organics such Paraffin is commonly associated with organics such as oil and asphaltenes and inorganics such as sand, rust, iron sulfide, and scale. The location of the deposit are dependent upon the cloud point (the lowest temperature at which the first paraffin is precipitated), an available surface and/or loss of precipitated), an available surface and/or loss of gas or light ends by a drop in pressure. While the paraffin is in solution, the oil may be Newtonian, paraffin is in solution, the oil may be Newtonian, but as paraffin particles begin to precipitate, the oil may become thixotropic. The composition of paraffin deposits may vary enormously, even in the paraffin deposits may vary enormously, even in the same field. Samples of paraffin from different depths in the same well have different peak carbon chain numbers, indicating a stepwise precipitation. In addition to properties that relate to the specific paraffin and produced wellstream, the mechanism of paraffin deposition is a function of pressure and temperature. In general, lower pressures pressure and temperature. In general, lower pressures increase the cloud point temperature. The range of cloud point temperatures of many paraffin crudes is such that paraffin may precipitate on the formation face and within the formation during the normal pressure depletion encountered over the well life. The reduction in producing rate may in practice be incorrectly attributed totally to depletion, when in fact, it is largely due to reduction in completion efficiency. It is the relationship between temperature and paraffin cloud point and solubility that is the paraffin cloud point and solubility that is the basis for one of the most universal methods of removing paraffin deposits from downhole tubulars and piping equipment; hot oiling. In many producing areas, particularly in rod pump systems, it is common practice to periodically treat with heated lease crude (sometimes in conjunction with paraffin treating chemicals) to melt and solubilize paraffin wax deposits. The most common method is to pump the heated crude down the tubing - casing annulus, which transmits heat through the tubing string to melt wax deposits on the tubing wall and rods. The solubilized paraffin is returned to the surface with the rest of the liquid wellstream. It has previously been postulated that the practice of hot oiling to remove paraffin wax practice of hot oiling to remove paraffin wax deposits on downhole equipment and tubulars could lead to chronic near-wellbore formation damage with the redepositing of waxes removed uphole and those waxes originally contained in the load oil. P. 577
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)