Sandstone Zones Research Articles

Deep Hydraulic Pumping-Reno Field

Abstract Hydraulic pumps set deeper than all other pumps in the world are producing at rates up to 3,400 BOPD in the Reno field, Wyo. The magnitude of producing rates, operating pressures and well depths provides interesting production engineering problems. This report is concerned with equipment design and layout for surface and bottom-hole pumping systems, and includes recommendations for optimum surface pumping equipment for future batteries. Operating problems associated with high-volume pumping from 15,000 ft are discussed, and plans are outlined for increasing production rates to more than 4,300 BOPD/well. Introduction Wells in the Reno field, located near Buffalo, Wyo., are particularly suited for casing-free hydraulic pumping because of their depth, high productivity and low GOR. Production problems have generally been handled by increasing the capacity of the production equipment and decreasing pressure drops in the system. The cost of hydraulic pumping equipment has been on the order of $100,000/ well for tae four completed wells. A study made in an attempt to reduce the cost of production equipment for future wells revealed the capital cost could not be significantly reduced for these 1,200+ B/D wells, but fewer, larger power oil pumps and. engines were recommended for future batteries to reduce operating costs, especially where fuel must be purchased. Since safety of the surface high-pressure oil-pumping system is important, the layout and design of the power oil system were carefully planned. Initial Development Recovery of 5,750 ft of oil during drill-stem test No.1 from Government Well 41X-24 in Jan" 1965, signaled the discovery of the Reno field. In Feb., 1966, the four completed wells in the Reno field produced an average of 8,465 BOPD from 15,000 ft. Casing-free hydraulic pumps are used for artificial lift. Development of the field is progressing with six rigs drilling in the area. Fig. 1 is a schematic drawing of a typical well completed in the Minnelusa (Tensleep) formation. Two of the zones are very fine to fine grain sandstone with dolomitic cement, and the third zone is micro-crystalline dolomite with porosity due to vugs. Table 1 shows reservoir and PVT data of interest. The reservoir originally had a static BHP of 6,600 psi and a low 450 psi bubble point. The crude bad a 34.9° API gravity and a GOR of less than 100 at a 30 psig separation pressure. The discovery well, perforated in only the two sandstone zones, bad an initial flowing rate of 800 BOPD, but then declined to a rate of approximately 530 BOPD (no water) with a 30 psig tubing pressure. Based on gradient curves, the flowing BHP was estimated to be 5,000 psi, indicating a PI of 0.3. Due to the low GOR, the well could not flow at rates much above 500 BOPD; therefore, artificial lift was installed to maximize production and aggressively determine the well's inflow performance relationships.

Transition of Condition on Hillsides Terraced against Avalanche

The authors have been carryiing out a survey about the transition of condition on hillsides where the terracing works for ground avalanche prevention were executed before. This paper presents the results of investigation conducted during the period of 1963-1965 on the snowy area with maximum snow depth of 2-3m in winter.The matters deduced from obtained data are as follows : 1) The terracing work shows gradually a decline of its function against avalanche in the course of breaking of executed terracing and soil accumulation on terraced steps. However, the function of terracing lasts effectually 20-25 years on every place except.the area susceptible to erosion such as sandstone zone.2) It is estimated that natural trees on the terraced hillsides generally begin to show the function against ground avalanche from the time of about 15 years after terracing execution.

Significant Oil and Gas Developments in Alaska, 1965-1966: ABSTRACT

Recent oil exploration in Alaska is centered in five sedimentary basins: Cook Inlet basin; Arctic (North) Slope province; Bristol Bay basin; Gulf of Alaska province; and Copper River basin. Surface and seismic exploration parties have been active in each, greatest emphasis being in the Cook Inlet basin and the Arctic (North) Slope province. The oil industry in Alaska during 1965 drilled 19 exploratory wells, resulting in the discovery of 3 oil fields, 3 gas fields, and extensions of 2 oil fields and 1 gas field. The 3 oil discoveries, all under Cook Inlet waters, are Granite Point, Trading Bay, and McArthur River. The gas discoveries are on the upland area of the Cook Inlet basin at Birch Hill, North Fork, and Moquawkie. The Granite Point discovery was extended north more than 3 mi. by subsequent drilling. A discovery was made 6 mi. south of production at Middle Ground Shoal. Gas production at the Cook Inlet field was extended about 2 mi. southwest. Two exploratory wells drilled in 1965-66 on the Arctic (North) Slope were reported non-productive. Two shallow dry exploratory wells were drilled on the north flank of the Co per River basin. Both were unsuccessful. The first two permanent platforms in Cook Inlet were installed at Middle Ground Shoal oil field during 1965, and development drilling began. A twin 8-mi. crude-oil pipeline was completed connecting the two platforms with an onshore treating facility. This furnished the first outlet for crude oil other than that at the Swanson River field. Contracts were let for 6 additional offshore-drilling and production platforms to be erected during 1966. End_Page 2029------------------------------ The most significant event since the discovery of oil in the Lower Kenai Conglomerate (Hemlock) at Swanson River was the discovery of multiple-pay sandstone beds in the Middle Kenai Formation. These sandstone beds furnish an additional objective and have higher porosity and permeability than the Lower Kenai Conglomerate. Gas pay zones have been found in both the Middle Kenai and Upper Kenai sandstone zones. End_of_Article - Last_Page 2030------------

Cyclic Sedimentary Sequences in Frontier Formation (Upper Cretaceous), Casper Arch Area, Wyoming, and Some Stratigraphic and Possible Paleoenvironmental Implications: ABSTRACT

The Frontier Formation is generally about 1,000 ft. thick in the Casper arch area and consists of a series End_Page 2035------------------------------ of asymmetric, upward-coarsening, depositional sequences referred to here as Four major cycles called sandstone zones by others, have been studied in exposures and mapped in the subsurface in a preliminary manner. Thinner, less conspicuous cycles occur within each major cycle. Where typically developed, a cycle begins with relatively non-sandy gray shale at the base and becomes progressively more sandy upward, terminating where the cycle is thickest with a conspicuous body of fine- to medium-grained, submature to mature, chert-rich orthoquartzite having a relatively sharp upper boundary. Chert-rich pebble conglomerate of uncertain origin occurs in places within the sandier parts of the cycles. Detailed correlations of bentonitic layers reveal that the major cycles pinch and swell laterally in a complex but generally systematic manner, displaying two- to four-fold thickness variations. The relatively thick parts of each major cycle generally lie on flanks of the underlying cycle. Proceeding upward through the sequence, axes of maximum sandstone development are offset progressively eastward away from the central Casper arch. The uppermost cycle also is relatively thick and sandy on the arch. Upward coarsening within the cycles and the complex, but orderly, shifting pattern of the depositional axes of the major cycles suggest that the rate of sediment influx exceeded the rate of subsidence in the area during deposition of the Frontier. The thickness variations are not most plausibly explained by differential compaction or by differential subsidence, at least in the lower three major cycles. Thickness trends suggest that the major source of sand was north and northwest of the Casper arch area. Although the cycles appear to be essentially regressive in nature, sand deposition under transgressive conditions is suggested in places by more glauconitic and (or) calcareous upper parts of the sandstone bodies. West of the Casper arch, coaly beds and channel-like conglomerate lenses directly overlie sandstone bodies in cycles that otherwise are similar. Definite evidence of non-marine deposition has not been observed in the Casper arch study area and general observations suggest that the sequence is essentially marine. As reasoned from stratigraphic observations, the general slope at the top of the lowermost major cycle did not exceed ½° and the maximum depth of water in the area was about 100 ft. Although understanding of the depositional agents must await additional studies specifically aimed at this objective, some analogies are drawn between gross characteristics of the cycles and typical features of deltaic deposits along modern shorelines. More realistic concepts of the internal geometry and genesis of sandstone and shale complexes could be of considerable aid to the petroleum geologist in explaining and predicting oil and gas occurrences. End_of_Article - Last_Page 2036------------

Geometry of Producing Mesaverde Sandstones, San Juan Basin: ABSTRACT

Within the San Juan basin the sandstone zones that occur at the top and bottom of the Mesaverde group were not deposited as a continuous blanket sand. In some areas thick, relatively clean sandstone units occur. In other areas thin, poorly sorted sandstone zones are found. These sandstone units exhibit a definite geometric pattern of distribution. Sandstone beds of the Point Lookout formation were deposited as a shoreline phase of a sea regressing northeastward. Sandstone zones of the Cliff House formation represent the shoreline of a sea transgressing southward at a later date. The shoreline along which these sands were deposited moved rapidly across some areas. In other areas, it remained stationary for relatively long periods of time. The thicker sands correspond to pl ces where the shoreline remained stationary for the longer periods of time. The successive positions of the various Cliff House and Point Lookout shorelines have been established both vertically on cross sections and laterally on maps. Those positions where the shoreline stabilized for relatively long periods of time are apparent in the form of steps that can be traced across the central part of the San Juan basin. The relatively thick, well sorted sandstone units that correspond with the positions where the shoreline stabilized have been divided into a series of benches of varying widths. Excellent examples of major steps in the Cliff House shoreline can be seen in surface exposures in the southeast and northwest parts of the San Juan basin. Those steps exposed at the surface in the northwest part of the basin exhibit the same strandline trend and in general are correlative with the steps found in the subsurface. End_of_Article - Last_Page 1250------------

Geochemical Investigations of Athabasca Oil Sands: ABSTRACT

Analyses were performed to evaluate the organic composition and the mineral content of the McMurray oil sands in northeastern Alberta, Canada. The samples came from the Abasand Quarry near McMurray and from three bore holes, drilled along a southwest-northeast cross section in the Fort MacKay and Bitumount area. The bitumen content is related to the particle size of the rock. Impregnation is not restricted to one particular sediment type in the McMurray formation. For example, sandstone zones in the Bitumount core were found to contain as much as 17 per cent organic material soluble in methylene chloride; the bitumen content of the shale layers is lower. The elementary composition of the organic material was found to be uniform throughout the entire 246-foot section of the McMurray formation in the core. An organic sulphur content of approximately 5 per cent extends throughout the core. The aromatic character of the bitumen was shown by spectroscopic methods of analysis. The bitumen contains End_Page 1253------------------------------ approximately the same amount of those hydrocarbons that may be recovered by n-heptane elution on silica gel columns. The abundantly available Abasand samples were subjected to detailed analysis. These samples represent the lower portion of the McMurray formation, lying a few feet above the Devonian limestone. The bitumen was found to be a complex mixture of hydrocarbon and non-hydrocarbon compounds; the character of a few of which can be indicated. The bitumen was observed to be susceptible to contaminations by microorganisms; this required precautions during analysis. The chemical composition of the samples indicates that the Athabasca bitumen is basically a crude oil. End_of_Article - Last_Page 1254------------

On the Subsurface Studies of Main Oil and Gas Fields in Taiwan (Part 2)

The Chinshui oil field succeeded in the well No. 5 for the first time. This is the second oil field in Taiwan which produces gas in great quantities with oil. Petroleum is producing from the lowest Shukkoko sandstone shale formation while gas is flowing from the upper sandstone shale formation and the white sandstone formation. The structure of this oil field is 5 km in length and is of anticlinal structure with somewhat steeperwest wing. Forty-seven wells were drilled up to the present and produced about 9, 200 kl petroleum and approximately 1, 870, 000, 000 m3 gas as of the end of April, 1956. This paper contains the result of the studies on the shallow zone Keichikurin formation in collaboration with the Chuton gas field, the conclusion of which is as follows: 1. In the sandstone zone at the top of Keichikurin formation rejuvenation of 1-2 wells of Chihchitze area by the gunperforation is possible, but in the Ia layer rejuvenation can not be expected. Both the underground structures of the sandstone zone at the top of Keichikurin and the Ia layer of Laotien Liao area located further below Chihchize, and there is a little hope of success there. 2. Judging from the change in the thickness of the each formation and etc, it is advisable to advance an examination into further lower formation by carrying out exploration in the depth.

Stratigraphic Traps in Denver Basin

The major oil and gas fields of the Denver basin produce from the D and J zones of the Lower Cretaceous Dakota sandstone. Lateral and vertical variations in grain size and permeability of these members localize oil accumulations both in conjunction with, and independent of, structural anomalies. Although only about half the fields may be classed as stratigraphic traps, some of the most prolific producers, Adena, Little Beaver, Harrisburg, and Bobcat, are stratigraphically controlled. In the producing area, the D zone is a continuous siltstone body containing local lenticular and shoestring sandstones. The J zone is a more continuous sandstone containing numerous silt and shale barriers near the top of the zone. Stratigraphic traps in the D and J zones are divided into five classes based on the form of the reservoir: (1) isolated sand lenses, (2) shoestring sand bodies, (3) updip barriers in sand bodies, (4) updip drop in roof of reservoir sand, (5) erratic cementation of sand.

The chalcocite-ore deposits at Corocoro, Bolivia

Clastic sediments which are the host rocks of copper mineralization in the Corocoro district, Bolivia, include west- dipping beds of the Vetas series, in which chalcocite ore bodies occur (mainly in arkose and sandstone zones in the San Marcos formation), and older east-dipping beds of the Ramos series. Native copper is the principal ore mineral in the Ramos beds, and may be a product of oxidation of an earlier mineralization genetically related to igneous activity. The chalcocite ores of the Vetas series are probably of syngenetic sedimentary origin and may have derived their copper content from erosion of the older rocks.

Little Beaver, Badger Creek, Middlemist Field Area, Colorado

The Little Beaver, Badger Creek, and Middlemist fields located on the eastern flank of the Denver basin produce oil and gas from partly sorted, lenticular channel sandstones modified by wave action. These permeable sands lie within more or less continuous, impermeable, gray, impure, sandstone and siltstone zones deposited in a shallow marine shelf sea during the Cretaceous period. Structural closure is almost absent and oil is found on small structural terraces. The producing sands may have originated as channel deposits on an irregular sea bottom resulting from minor tectonic movements, compaction over old erosion surfaces, or from slumping as a result of solution or flowage in the Permian evaporite section below. Local low areas on the sea floor were filled with channel sands later partly redistributed as bar-like features by wave action. Overlying Upper Cretaceous shale sediments were differentially compacted above these local sand lenses. Tectonic movements in the late Cretaceous and early Tertiary affected the entire Cretaceous section and modified previously formed minor Cretaceous structural elements. Shallow structural markers reflect structure present on the top of the producing sands. Five critical isopachous intervals in addition to structural data are important in localizing producing sand lenses. These structural and isopachous criteria may be useful in extending present producing fields and in finding other lenticular sands in the Denver basin.

Developments in Oklahoma in 1948

Although fewer outstanding discoveries were made in undeveloped regions of Oklahoma during 1948, substantial reserves were added by wildcat discoveries and extensions especially on the southwest flank and in the southeastern embayment of the Anadarko basin, the Ardmore basin, the Seminole area, and in east-central Oklahoma. The outstanding development in Oklahoma during 1948, from a regional exploration point of view, was the continued success of exploratory drilling in the Elk City area, on the southwest flank of the Anadarko basin, which emphasized the geologic significance of granite wash production in Oklahoma. Discoveries in this area resulted in further leasing and exploration in the entire southwest Anadarko basin extending from Oklahoma into the Texas Panhandle. Production of oil increased to 155,578,453 barrels, representing an increase of 9.9 per cent over the 1947 production. Total reserves of crude oil increased by 31 per cent. Production of marketed natural gas increased to 276,542,084,000 cubic feet and casinghead gas to 178,751,567,000 cubic feet, or 12 per cent over the gas marketed in 1947. Total reserves of natural gas were estimated to be practically the same at 11,332,445 million cubic feet at the end of 1948. In number of holes drilled Oklahoma ranked second with a total of 3,827, of which 713 were wildcats resulting in 94 new discoveries. The deepest producing well in Oklahoma, one of the deepest in the world, was completed during 1948 in an Ordovician sandstone zone from 12,855 to 13,611 feet.

Moorefield Formation and Ruddell Shale, Batesville District, Arkansas

The Moorefield formation in the Batesville district, Independence County, Arkansas, consists of a lower member of black calcareous shale and limestone and an upper member of dark gray fissile clay shale. The lower member has been known as the Spring Creek limestone (name preoccupied) and grades laterally into chert that has been mapped incorrectly as Boone chert. It is recommended that the name Moorefield formation be restricted to the lower member, and that the name Ruddell shale be erected for the upper member. The fossil assemblages indicate that the Moorefield formation (restricted) represents the British P1 (G1) or Goniatites crenistria zone and the Ruddell shale together with the overlying Batesville sandstone, the P2 (G2) or Goniatites striatus zone of the upper Visean stage of the European Carboniferous section. The Moorefield formation (restricted) is correlated tentatively with the St. Louis limestone and the Ruddell shale with the Ste. Genevieve limestone of the central Mississippi Valley section.

Walnut Bend Pool of Cooke County, Texas: ABSTRACT

The Walnut Bend pool is the first major deep discovery in the Marietta-Sherman syncline, a northwest-southeast trending feature which extends from southwestern Carter County, Oklahoma, to southeastern Grayson County, Texas, parallel to the Criner Hills axis and the Muenster Arch. In this pool 1,000 feet of Comanche rocks overlie the 4,200 feet of Upper and Middle Pennsylvanian (Canyon and Strawn) sediments, and beds of lower Simpson (Oil Creek) age underlie the Pennsylvanian rocks. Pre-Pennsylvanian rocks show the Walnut Bend structure as an elongate anticline. This structure was formed on an arch folded in early Pennsylvanian (pre-Bostwick) time and the Marietta-Sherman syncline was formed in late Deese time by the downwarping of the middle part of this arch. Over one an one-half million barrels of oil have been produced from 6 sandstone zones between the depths of 4,100 and 5,100 feet, and from 2 dolomite beds in the Simpson group. Occurrence of oil in the sandstone zones at 4,900 and 5,100 feet is controlled by anticlinal structure over the closely folded Ordovician beds, Electrical log cross sections are presented to indicate that oil in the 4,100-, 4,600- and 4,700-foot zones occurs in a stratigraphic trap formed by gradation of standstone into shale. End_of_Article - Last_Page 941------------

XXVI.— On the Upper Formations of the New Red Sandstone System in Gloucestershire, Worcestershire, and Warwickshire; showing that the Red or Saliferous Marls, including a peculiar Zone of Sandstone, represent the “Keuper” or “ Marnes Irisées;” with some account of the underlying Sandstone of Ombersley, Bromsgrove, and Warwick, proving that it is the “Bunter Sandstein” or “Grès Bigarré” of Foreign

Preface. In former communications to the Geological Society*, the System of the New Red Sandstone of Gloucestershire, Worcestershire, and Shropshire was subdivided by Mr. Murchison in the following manner: | | Foreign Equivalents. | |:---------------------------------------------------------- | -------------------------------- | | 1. Marls with salt, gypsum, and a thin course of sandstone | Keuper — Marnes Irisees. | | 2. Quartzose red sandstone, and conglomerate | Bunter Sandstein — Gres Bigarre. | | 3. Calcareous conglomerate=magnesian limestone | Zechstein. | | 4. Lower new red sandstone | Rohe-Todte-Liegende. | The objects of this Memoir are to describe with greater precision than had been previously attempted, the two superior members of this group, by showing that they are both fossiliferous, and that they can be separated from each other by their zoological and lithological characters, as well as by geological position. The communication is the result of a joint examination of the district, and of other observations made independently by the authors. In it, they propose to describe the prominent characters of the two superior formations of the New Red System as exhibited in Gloucestershire and Worcestershire, and to extend their remarks concerning those beds into Warwickshire. The strata will be considered in descending order. § 1. Saliferous Marls and Sandstone (For, Syn. Keuper—Marnes Irtsees.). Having examined the junction-beds between the lias and the new red sandstone from the southern extremity of Gloucestershire through Worcestershire into Warwickshire, we have only to repeat what was adduced by one of us on previous occasions, that in many positions the lowest calcareous band or “limestone of the lower lias shale” is also underlaid by shale, which