GEOLOGICAL ASPECTS OF OILFIELD DEVELOPMENT Chairman and General Reporter: J. ROMANES, F.G.S., KINST.P.T. GENERAL REPORTER'S
. THE thirteen papers in this section were divided into five groups, and a general discussion took place after each group of papers had been presented. The five groups were : (1) General Development Schemes Involving Gas Con. ervation, Edge-Water, Group Production, etc. Papers by Abraham, Versluys and Chahnazaroff. (2) Unit Development of Oilfields.Papers by Umpleby and Southwell. (3) Methods of Increasing Oil Recovery. Paper by Nowels. (4) Evidence Provided by Coring, Flush Sampling, etc. Papers by Sansom, Evans, Faucher, Lewis and Barnes, Bentz and Strobel, and Corps. (5) Electrical Logging.Papers by Schlumberger and Sutton Bowman. The first three of these groups deal more especially with subjects in the sphere of interest common to the geologist and the production engineer. Taken collectively the subject was: Given a potential oilfield what is the best method of: (a) Discovering the essential data regarding it; (b) Given that data the most efficient method of exploiting it. Obviously, in discussing such a subject, the advantages of unit development as put forward in the second group must be assumed, as otherwise exploitation develops into a mere scramble for maximum production. The main point brought out was the difficulty of striking a balance between encroaching edge water and the spread of the gas cap, and one could not help feeling that in spite of the ideal conditions of unit operation, much unproductive drilling might be required in any given field to obtain the data necessary for efficient exploitation, and that from the purely economic side the pros and cons must be carefully weighed up. The other two groups of papers deal especially with the problems of the exploitation geologist as opposed to the broader problems of geological exploration and are in the main devoted to methods of obtaining the maximum geological information in the course of developing an oilfield. These papers bring out clearly the enormous advance which has , been made in recent years in the scientific analysis of data provided during the drilling up of an oilfield. No longer is the log of a well in general geological terms sufficient, but the geologist's task, apart from determination of horizon, etc., involves determination of porosity and permeability of sands, and the analysis and significance of waters encountered, while in electrical logging of wells the possibilities of geophysical assistance is brought home to him. Finally, the use of ultra-violet light is another weapon put into his hand; this is probably only in its infancy but already of great practical value.
1 REJUVENATION OF OILFIELDS BY NATURAL AND ARTIFICIAL WATER FLOODING By K. B. NOWELS *
. AT present there are three methods of rejuvenating oilfields repressuring the oil-sands with gas, air or with water. This paper describes the latter method, which is known as the forced drive " or " water flooding system."There is only one place in the world where this method of rejuvenation is used on a large scale; that is, in the Bradford and Allegany field of north-western Pennsylvania and south-western New York. Flooding has been responsible for the complete revival of the Bradford field, which has been producing for sixty-two years. Out of a total of 85,000 acres, there remains 69,000 acres yet to be developed and produced by water flooding. This paper briefly traces the development of flooding since its beginning and describes present-day methods. A discussion of development costs, equipment used, and a brief summary of existing view-points concerning some of the technical phases of this type of rejuvenation is given. Although recoveries from flooding operations have been small, compared with the recoveries obtained from natural production in other producing districts of the world, they are sufficient, nevertheless, to make flooding operations profitable. In the old, natural floods where hydrostatic pressure alone was used, the average recovery was approximately 3960 barrels per acre.Present-day flooding involving the use of pump pressure to augment hydrostatic pressure gives recoveries of approximately 6000 barrels per acre on leases with which the writer is familiar. The average flood well produces about 16 barrels per day at its peak. -Peak production is generally reached four and onehalf months after the beginning of a flood, and the average well has a total life of approximately thirty and one-half months. Wells closely spaced yield higher peak productions than widely spaced wells for any gives pressure, and their productive life is shorter. Wider spaced wells, however, may be given the characteristics of closely spaced wells by means of increased pressure applied at the water intake wells. There are two schools of thought concerning the shape of the flood zone between wells, and these points are briefly discussed in the paper. It is the writer's opinion that eventually flooding will be found successful and economically practicable in the rejuvenation of other old oilfields, providing plentiful supplies of satisfactory water for flooding are available, and the producing sand is not too variable in permeability.
. Up to the present time petroleum technology has developed for use three artificial methods for the rejuvenation of oilfields. These are: repressuring the oil-sand with gas, air or with water, the latter being known as the " forced drive " or " water flooding " system. All these methods employ the fundamental process of restoring in some manner the depleted energy which once existed in the oil-sand and was responsi
CONTRIBUTI DELLA GEOFISICA AGLI STUDI GEOPETROLIFERI DELL'AZIENDA GENERALE ITALIANA PETROLI Per A. BELLUIGI SunazaRY. TFiE geophysical work, accomplished by the A.G.I.P. for oil search in Italy, concerns the prospecting of vast plains in the valley of the Po and in the hills for nearly 12,000 Km.a. First: the gravimetrical methods were used and after these the magnetical and electrical methods (particularly the Wenner method). Until now- the. seismic methods, have had no extensive use, because the particular structure did not allow the employment of these methods; but they will be used principally for the research in the substructure in Central and South Italy. It is observed that the types of deep structure in the valley of the Po are characterised by masses, which disturb in a gravimetrical manner by a positive differential density, which varies according to the depth. This fact has introduced various difficulties, chiefly in the interpretation of the results of gravimetrical surveys, which are made by the geophysical branch of the A.G.I.P. Contrasting theories are published in Ergänzungshefte für Geophysik and Gerlands Beitrdge, Leipzig. The geological difficulties are reflected in a certain degree by the geophysical difficulties and it is well known how difficult the research and the interpretation of the structure of the Apennines are. Anyway, in many cases, the physical properties of deep structures are only distinguished by small variations. This has implied the highest care in the experimental work and in the correction of the various disturbing causes, and where the field-work has been accomplished there were many new problems to be re-solved for giving exactly the particular geological interpretation. Besides, the difficulties are increased, i.e. in the gravimetrical research by the appearance of strong isostatical influences or regional characteristics. In the valley of the Po two big tectonical directions with the occurrence of gravimetrical anticlines (with a superfluity of local gravity) have been observed, and some have been confirmed by drilling operations. An interpretation of the configuration of their gravity in the valley; of the Po is given, and the relation between this configuration and the existence of hydrocarbonic layers. It is necessary to continue the simultaneous employment of different prospecting methods to observe the characteristics and to explain the resulting questions. Col. R: D. L. N. 300, 13 febbra o 1927, emanato dallo Stato italiano, venne conferito all' Ente parastatale A.G.I.P. l'incarico di effettuare ricerche petrolifere nel sottosuolo del Regno per integrare l'opera che già da arini in questo campo andava sviluppando l'industria privata per mezzo di apposite Società. L'opera di queste aveva rivelata-nella falda pedemontana Appenninica, tra Piacenza e Fornovo Taro, la presenza di idrocarburi liquidi abbastanza: leggeri, in strutture tettonicamente e
DEVELOPMENT OF METHODS OF MEASUREMENT OF TENDENCY TO SMOKE By WALTER A. WOODROW, A.I.C., F.C.S., M.Inst.P.T SINCE the paper by Kewley and Jackson (J. In8t. Petr. Tech., 1927, 13, 364), very little information is available in the literature regarding methods of estimating tendency to smoke. It is of interest to mention that a type of smoke test was used by Grote and Hundsd6rfer (Petr. Z., 13.7.32, 28,9-14) during the comparisons made for candle-power values of a Rumanian kerosine which had been refined with increasing quantities of sulphur dioxide. The authors used a 14-inch Kosmos lamp, with a clay plate supported above the lamp at a definite distance. The purpose of the clay plate was to collect any surplus soot which was not deposited on the lamp glass. The authors found that kerosine fractions refined with sulphur dioxide smoked the lamp glasses and, clay plates to a lesser degree than did kerosines which had been acid-refined. Minchin (J. In8t. Petr. Tech., 1931, 17, 102) has investigated the subject of tendency to smoke, using prepared types of paraffins, naphthenes and aromatic hydrocarbons of similar boiling range, measuring the smoking points (maximum flame heights) in a Weber photometer lamp. The author states that the tendency to smoke f of a kerosine is directly proportional to its aromatic or naphthene content, and, in general, directly proportional to the boiling range, tendency to smoke increasing with rise of boiling point. On the other hand, dealing with homologous series, the tendency to smoke, with the exception of the paraffins, decreases with the increase in the number of carbon atoms or boiling point. This is because the molecules become more parafinc and the influence of the nucleus (benzene or naphthene ring) becomes more balanced by the very much smaller sooting properties of the paraffins. A relationship between tendency to smoke and aniline point is given. Extrapolation of the curves for tendency to smoke of paraffin-naphthene and paraffin-aromatic mixtures cross the same point on the ordinates, which point representing 100% paraffins indicates the tendency to smoke value of pure paraffins to be 4-4. Comparative figures of 4-4, 13-1 and 42-4 are given as the tendency to smoke of paraffins, naphthenes and aromatics respectively, taking an average from eight to seventeen carbon atoms in each case. The author mentions that a figure of 13-1 represents an excellent kerosine, and suggests that any method of refining for the removal of aromatics should remove the minimum amount of naphthenes to obtain the best results. THE EFFORTS OF THE INSTITUTION OF PETROLEUM TECHNOLOGISTS TO PRODUCE A SMOKE POINT TEST. In 1931 the Institution decided that a sub-committee should be formed to investigate the necessity for a * Representative of the Standardization Sub-Committee on Tendency to Smoke, Institution of Petroleum Technologists. t Tendency to smoke was calculated by the empirical formula Tendency to Smoke =320 Maximum Flame Height s
DISCUSSION. Mr. P. Evans suggested that the aneroid had not received the attention it deserved, either in geological survey work or in literature, and he therefore welcomed Dr. Bowman's contribution. His own experience was, however, that the accuracy suggested by Dr. Bowman could not be attained in Assam, as the diurnal variation curve was not sufficiently constant from day to day. He also thought that the use of the computation sheet (forming Fig. 1 of Dr. Bowman's paper) for all stations involved rather a lengthy calculation and that such a refinement should be attempted for only the more important stations.The method of utilising the vertical heights as base-lines for horizontal measurements had many advantages, but the speaker stated that he was not clear whether in making use of a vertical base, Dr. Bowman had been able to take advantage of the presence of peaks of previously known height, only the lower read. ing being barometric, or whether in all instances both the height readings needed for a basic vertical interval were obtained by the aneroid. In the latter case it seemed that there might be some difficulty in - obtaining the necessary vertical range unless a few prominent points were specially visited, which might prove difficult if the greater part of the work consisted of stream traverses.
SCIENCE IN THE PETROLEUM INDUSTRY* By SIR JOHN CADMAN, G.C.M.G., D.Sc. TIE Royal Institution and the Lecture Theatre in which we are assembled to-night are associated with a long tradition of scientific work. Many famous scientists have spoken from this table and have performed here experiments which were destined to revolutionise wide phases of life and to throw light upon mysteries which ,had previously been enshrouded in obscurity. Humphry Davy was one of the first Professors at the Institution. His chemical researches brought him the world-wide fame which has ever since been accorded to him. His research on the miner's safety lamp and the control of methane ignition by means of a wire gauze was epoch-making; and the oil safety lamp of to-day is designed on the principle which he evolved. Davy was followed, after an interval, by Michael Faraday. Faraday's career is an object lesson to all aspiring young men. Apprenticed as a youth to a book-binder, he had high ideals respecting education and culture. After being taken, in 1812, by a customer of his master to hear lectures by Davy, he made notes, amplified them, and finally sent a report of the lectures to Davy himself. In the following year, Faraday became Davy's assistant. In 1825 he was appointed Director of the- Laboratory; and in 1833 just 100 years ago-he became the first Fullerian Professor of Chemistry, an appointment which he held till the end of his life. The petroleum industry is under a great debt to Faraday. It was he who first isolated benzole in the course of studying the gas from cracked oil, and by so doing may be said to have laid the foundation of the petroleum industry. This audience, composed of delegates to the World Petroleum Congress, owes a tribute to the memory of Faraday. j Davy and Faraday have been succeeded by men no less worthy than they of this Institution. Dewar carried on the work of Fullerian Professor of Chemistry from 1877 to 1923. The brilliance of his lectures was equalled by that of his laboratory work on the liquefaction of gases and the properties of matter at low temperatures. It was Dewar who made possible the commercial extraction of helium and the low-temperature rectification of liquefied gases. He was followed by the present Resident Professor, Sir William Bragg, who is noted in the world of Science for his work by X-ray analysis on the elucidation of crystal structures and of solid substances generally.His achievements here will entitle him to a high place in the history of scientific research and in the future. his name will be coupled with those of the other distinguished men who have preceded him. Before proceeding with the experiments which it has been arranged to show you to-night it is appropriate to draw attention to two interesting landmarks in the recent history of petroleum * Lecture delivered at the Royal Institution on July 21st, 1933. f At this point the audience rose and stood in silence in memory of Faraday. 1. The
SULPHURIC ACID TREATMENT, OF CRACKED DISTILLATES By JACQUE C. MORRELL and GUSTAV EGLOFF,-Ph.D., M.A., M.Am:Inst.Chem.E., M.Arn.Chem.Soc., ' M.Inst.P.T DESPITE the large amount of research that has been carried on for years to find other methods, sulphuric acid treatment is still dominant in the refining of cracked distillates., This report relates to the treatment of cracked gasolines with sulphuric acid and its effect upon the polymerisation and solution losses, desulphurisation, octane rating, gum and colour. In general, petroleum distillates are refined by chemical and physico-chemical methods. In the refining of cracked distillates by chemical methods, many reagents besides sulphuric. acid have been proposed, including other 'acids and heavy metal salts. As examples of the physico-chemical methods of treatment may be mentioned the use of adsorbents which include the various earths such ras fuller's earth, bentonite and bauxite. The hydrocarbons are treated by the adsorbent earths in liquid or vapour phase. CHEMISTRY OF REFINING. It may be stated briefly that cracked distillates contain the four major groups of hydrocarbons-namely, unsaturated, aromatic, naphthene and paraffin hydrocarbons. , The paraffins, with the possible exception of methane, react to some extent with sulphuric acid containing high percentages of sulphur trioxide, the reaction being more pronounced with increasing temperatures. The lower members of the naphthene series react with concentrated sulphuric acid, the reactivity decreasing with increasing molecular weight. Aromatic hydrocarbons dissolve to a considerable extent in sulphuric acid, particularly in concentrations above 80%, the solubility increasing as the concentration of the acid increases. The unsaturated or olefin hydrocarbons are the most reactive group, and will therefore be discussed in some detail. reactions involving the union of two or more unlike molecules may for present purposes also be included under the general term " polymerisation." In the sulphuric acid treatment of cracked distillates the losses may be divided into two componentsnamely, the solution and the polymerisation losses. The solution loss is the volume or percentage of distillate which is removed by reaction with the, acid and solu tion in the sludge.The polymerisation loss refers to the portion of the gasoline which is converted into higherboiling hydrocarbon fractions. The polymerisation loss may be calculated by the following formula :. A(B-[C+D]) B A equals 100 minus the per cent. solution loss, B equals per cent. 410 F. end-point gasoline in untreated cracked distillate, C equals per cent. 410 F. end-point gasoline in treated cracked distillate, D equals per cent. distillation loss on distilling treated cracked distillate. The formula gives the polymerisation loss in terms of gasoline content in the untreated cracked distillate, and not in terms of the treated cracked distillate. ACID SLUDGE-ACID RATIO. The acid slud
UNIT DEVELOPMENT OF OILFIELDS By Dr. J. B. UMPLEBY
. UNIT operation of oil pools is a means to an end and not an end in itself.Its object is to procure more oil from each acre at less cost per barrel.Only through the operating of pools as single natural units can greatest use be made of the energy stored in the reservoir in producing oil. This energy once dissipated cannot be restored. Efficient development calls for a. careful prospecting of reservoir conditions in order to determine the best distribution and density of wells. Development plans must be subject to modification as new information is acquired. This cannot be done under divided competitive ownership. Best operation calls for the least consumption of reservoir energy per barrel of oil produced, the least possible wastage of gas, the recycling of excess gas or even the introduction of gas from extraneous sources, and freedom of choice in selecting wells for production and pressure maintenance. Gas should not be marketed until oil production has ceased to be profitable. These things cannot be accomplished under divided competitive ownership. Efforts toward unit development should be directed towards new areas rather than towards old fields. Legal recognition of acreage content as the basis of ownership and of reservoir energy as a common attribute of a pool to be used to a maximum in producing oil would remove the chief difficulties confronting unitisation efforts. It is believed that with these two points covered and a law requiring that drilling permits for wild-cat wells be granted only on unitised blocks, it would be feasible to leave the details of unit formation to the lease and royalty owners.Agreements might take many forms and yet serve the major purpose. Unitisation may be accomplished theoretically, either by voluntary agreement or under compulsory regulation. It is concluded that, from a practical standpoint, elements of compulsion are necessary. The advantages of unitisation to all interested parties, including the general public, and the intricacies, injustices, and wastefulness of current practices, are believed to justify and make feasible the necessary application of the police power to bring it about.
. The unit development of oilfields seeks increased recovery, lowered costs, and stabilised output through the application of advanced engineering principles. It is not an end in itself and only becomes a problem in pools of divided ownership.It recognises that the oil pool is the one economic unit given to the industry by nature and that to subdivide such a natural unit into competitive parts makes for reduced recovery, increased costs and leads to a chain of economic consequences adverse both to the industry and to the consuming public. Competition should operate between units and not between parts of a unit that by nature is indivisible. Unitisation is a device, and only a device, to make possible the orderly testing, development and operation of a
THE POSSIBILITY OF THE GASOLINE DETERMINATION OF POTENTIAL GUM IN BY ULTRA-VIOLET RAYS By Dr. M. FREUND, Budapest (Hungary)
.. 1. IT is shown that a short exposure to the action of ultraviolet rays seems to give a measure of the potential gum content of cracked gasolines.The method of testing is described. 2. The results of exposure to ultra-violet rays for ten minutes, seem to agree very closely with those of corresponding storage tests. 3. The elementary compositions, calculated as pure CH substance, of the dissolved gum formed on ultra-violet light exposure, or during storage in the dark in the presence of air, or under influence of oxygen by means of ageing tests, appear to be similar with regard to the gasolines investigated. The precipitates of gum which were separated seem to show the same characteristics. 4. The oxygen contents of the gum substances produced seem to depend upon the conditions of gum formation and on the preparation of the samples.. 5. It is indicated that by a short exposure to ultra-violet rays, or by a certain storage period in the dark, or by the influence of oxygen, the most unstable hydrocarbon groups react first to give gum, and this seems to' determine the potential gum content of the gasolines.
. According to various authors, gum formation in cracked gasolines is closely related to oxidation processes which occur during storage, and it is evident that the most unstable hydrocarbon groups probably react first under the influence of polymerising agents. Preferential action of this type is indicated by the effect of treatment of cracked gasolines with aluminium chloride, zinc chloride, fuller's earth, etc., all of which are successful in producing stable motor fuels, although the gum-forming constituents are polymerised and separated in the absence of oxygen. The methods available for the determination of potential gum are based without exception on the accelerated oxidation of the gasolines dealt with, but opinions as to the usefulness of these ageing tests are divergent. Photochemical reactions are likewise able to polymerise certain hydrocarbon compounds, and this research work deals with the possibility of the determination and separation of potential gum in gasolines under the action of ultra-violet rays. IATERATURE. For the determination of potential gum Voorhees and, Eisinger 1 propose to estimate the weight of gum produced in gasoline by heating in a glass flask filled with oxygen. , This method, referred to as the " Oxygen Gum Test," has been used during the investigation but did not always give a good agreement with the results of actual storage. Other methods for the evaluation of gum stability measure the oxygen consumption, or the length of induction period preceding actual oxygen absorption. For instance, Voorhees and Eisinger,l using their second method, treat the gasolines at 100 C. in an oxygenfilled glass flask, connected to a gas burette and mercury manometer, using. a
COLD-TREATING PROCESS FOR CRACKED NAPHTHAS By R. A. HALLORAN
. A DESCRIPTION is presented of a cold-treating process developed for the treatment of cracked naphtha. The most important feature of the process lies in the use of strong sulphuric acid at controlled temperatures obtained by refrigeration. The process has made possible the economical treatment of pressure naphthas of even high sulphur content. Its principal advantages over the normal method of acid treatment are (a) Increased gasoline yields due to decreased polymerisation and treating losses. (b) Decreased acid requirements. (c) Conservation of valuable anti-knock constituents. (d) Decreased caustic requirements. (e) Improved recovery of acid from sludge.
. The chemical composition of cracked naphtha depends not only on the type of charging stock used, but also on the type of cracking process and methods of operation. However, all cracked naphthas contain four main classes of hydrocarbons-paraffins, naphthenes, aromatics and olefines, but the proportions of these compounds are subject to variation. In addition to these general classes of hydrocarbons, which constitute the greater part of the naphtha; there are also present in smaller amounts di-olefines and acetylenes ; some nitrogen compounds, organic acids, and phenolic bodies; also varying amounts of sulphur compounds, such as mercaptans, organic sulphides, thiophenes, and hydrogen sulphide. The four main classes of hydrocarbons are, in general, satisfactory constituents of gasoline. The other classes of compounds possess undesirable properties and therefore should be removed. For example, the di-olefines and acetylenes are unstable and may form gummy products by oxidation and condensation; the organic acids and nitrogen compounds are coloured; some of the sulphur compounds are corrosive, while all of them when present in large amounts may cause corrosion in engines, due to their products of combustion. The refining problem, as considered in this paper, therefore resolves,itself into the following phases a. Sulphur reduction; b. Elimination of gum-forming constituents; and c. Production of good, stable colour. The removal of hydrogen sulphide prior to the regular treatment and the details of the distillation steps following treatment, to produce the desired boiling points, are outside the scope of this paper.. REFINrNG PROCESSES. There are a large number of processes employed at the present time for refining gasoline to a desired standard of quality. The method varies with the individual refiner and with the nature or geographical source of the stock to be refined. Probably the most extensively used method involves treatment with sulphuric acid followed by distillation of the acid-treated stock.Other processes make use of hypochlorite solutions, silica gel, fuller's earth, impregnated clays, and many other reagents or combinations of reagents.However, the most effective * Standard Oil Company of California.