Types Of Secondary Changes Research Articles

INFLUENCE OF SECONDARY CHANGES ON THE COLLECTOR RELIABILITY COEFFICIENT IN GEOLOGICAL MODELS OF OIL AND GAS DEPOSITS

Secondary changes in reservoir rocks, depending on their type, have a significant effect on filtration-capacitive properties (FCP). The result of this effect is a significant complication of the pore space of the reservoir and, as a consequence, the connectivity of the reservoir. The connectivity parameter is an important criterion when choosing multivariate modeling methods and sandstone cube construction parameters when creating geological models. The paper discusses the methods used today to calculate reservoir connectivity in geological models of oil and gas deposits, evaluate their effectiveness and propose a new approach to determining the connectivity parameter depending on the type of secondary changes in reservoir rocks and the geometry of the natural reservoir. In addition, an example shows the dependence of the coupling coefficient on the main parameters of the geological model: sandiness, ranks of variograms and the nugget effect. The proposed method allows to estimate the anisotropy of the main types of secondary changes in various directions and to assess FCP changes in geological models.

REGULARITIES OF ACCOMMODATIONS OF MAIN TYPES OF SECONDARY CHANGES OF COLLECTORS IN THE TERRITORY OF THE WEST SIBERIAN PLATE

To date, hydrocarbon raw materials play an important role in the economy of the Russian Federation. Federal state statistics service of Russia Federation data show that for the first seven months of 2018, revenues from hydrocarbon production accounted for about 40 % of all federal budget revenues, and this number will only increase in the near future. However, in the last fifteen to twenty years in the main oil and gas bearing provinces, including the Western Siberia, have seen a stable decrease in production levels. New opportunities to change the current trend is to involve in the process of developing oil and gas deposits in poorly studied areas with a high density of hydrocarbons. Such objects, as a rule, are characterized by an extremely complex geological structure and the pres- ence of different types of secondary changes of rock-collectors. Despite the large number of such objects, at the moment there is not only a clear classification of the main types of secondary changes, but also the patterns of their location and, as a result, the methods of prospecting and exploration of deposits of this type are not sufficiently developed. In this paper there made an attempt for generalize the extensive material on the study of collectors with a modified pore space structure and to determine the main patterns of location of the main types of secondary changes on the territory of the West Siberian Plate.

METHODOLOGY OF DISTRIBUTION ZONES OF SECONDARY CHANGES OF RESERVOIR ROCKS (ON THE EXAMPLE OF DEPOSITS IN THE NORTH OF WESTERN SIBERIA)

Over the last twenty years, the main oil and gas provinces in Russia have a stable decrease in hydrocarbons production level. Western Siberia is not exception, where oil and gas are active produced over last fifty years. The basic principles of providing a high level of production are involvement in the development process new hydrocarbon deposits, which, as a rule, are characterized by a complex geological structure and the availability of one or several types of secondary changes of reservoir rocks. According to the author's estimation, based on the study of the core material of more than thirty deposits located in the northern part of the Western Siberia, most of reservoir rocks the jurassic and cretaceous age are affected to secondary changes. In the area of maximum demonstrations of secondary paragene- ses, there are concentrated about 15-20 % of the overall capacity of resource base in Western Siberia. The current situation has led to the need for scientific and technical work, as a result of which the author has pro- posed a method for identifying zones of maximum concentrations of sec- ondary changes in reservoir rocks. The result of the proposed technique is the ability to determine the type of secondary changes and the degree of its influence on the structure of the pore space at any stages of geological exploration, delineating the area of maximum concentrations of secondary parageneses, obtaining corrected drilling rates, research programs and optimizing the development of hydrocarbon deposits. An effective methodology allows with a high degree of certainty to iden- tify zones of secondary changes of reservoir rocks, as well as improve the quality of geological exploration work and the effectiveness of exploration drilling.

MAIN FACTORS THAT CONTROL THE DISTRIBUTION OF THE BASIC TYPES OF SECONDARY CHANGES OF RESERVOIR ROCKS

Secondary changes in reservoir rocks in the territory of Western Siberia have a regional distribution pattern, and the amount of oil and gas resources, that are in these zones, reaches 30 % of their total number. Part of the objects where the secondary changes are most clearly manifested, has not yet been introduced into the development, what requires a more detailed approach to planning and conducting geological exploration work in perspective areas, where pore space is modified by secondary processes. In this work the main factors that control the distribution of the main types of secondary changes in reservoir rocks were identified: lithofacies, chemical and tectonic.

THE BASIC TYPES OF SECONDARY CHANGES IN RESERVOIR ROCKS IN THE TERRITORY OF THE WEST SIBERIA PLATE

On the example of the group of fields in the West Siberia North the basic types of secondary changes in reservoir rocks are reviewed. Some of the most common types of such changes in the West Siberian plate territory include the processes of zeolitization, carbonation and leaching. These processes have, as a rule, a regional character of distribution and are confined to the tectonically active zones of the earth's crust. Due to formation of different mineral paragenesises the secondary processes differently affect the reservoir rocks porosity and permeability: thus, zeolitization and carbonization promote to reducing the porosity and permeability and leaching improvement. All this, ultimately leads to a change of the oil recovery factor and hydrocarbons production levels. Study and taking into account of the reservoir rocks secondary change processes can considerably influence on placement of operating well stock and on planning of geological and technological actions.

ETV6/RUNX1 abrogates mitotic checkpoint function and targets its key player MAD2L1

Approximately 25% of childhood B-cell precursor acute lymphoblastic leukemia have an ETV6/RUNX1 (E/R) gene fusion that results from a t(12;21). This genetic subgroup of leukemia is associated with near-triploidy, near-tetraploidy, and trisomy 21 as rather specific types of secondary changes. Here, we show that, unlike various controls, E/R-expressing Ba/F3 clones acquire a tetraploid karyotype on prolonged culture, corroborating the assumption that E/R may attenuate the mitotic checkpoint (MC). Consistent with this notion, E/R-expressing diploid murine and human cell lines have decreased proportions of cells with 4N DNA content and a lower mitotic index when treated with spindle toxins. Moreover, both RUNX1 and E/R regulate mitotic arrest-deficient 2 L1 (MAD2L1), an essential MC component, by binding to promoter-inherent RUNX1 sites, which results in down-regulation of MAD2L1 mRNA and protein in E/R-expressing cells. Forced expression of E/R also abolishes RUNX1-induced reporter activation, whereas E/R with a mutant DNA-binding site leads to only minor effects. Our data link for the first time E/R, MC, and MAD2L1 and provide new insights into the function of the E/R fusion gene product. Although tetraploidy is an almost exclusive feature of E/R-positive leukemias, its rarity within this particular subgroup implies that further yet unknown factors are required for its manifestation.

MR imaging analysis of heterogeneous leiomyomas of the uterus.

Thirty-six leiomyomas from the same number of patients that were heterogeneous on MR imaging were evaluated for analyzing their MR patterns and for differentiating each type of secondary changes by means of MR imaging-pathologic correlation. The tumors with a mean diameter of 9 cm could be classified into 4 patterns depending on the morphological appearance of signal intensity: speckled (n = 14); nodular (n = 11); cystic (n = 9); or indeterminate (n = 2). Speckled pattern was associated with a mild degree of hyaline or myxoid degeneration or focal necrosis. Nodular pattern was caused by necrosis or cellular leiomyoma, and cystic pattern was related to severe hyaline or myxoid degeneration or necrosis. Each type of secondary changes within leiomyomas showed distinctive MR findings, if they were severely involved. However, use of an additional contrast-enhanced study was necessary in some instances for further clarification. MR imaging has a potential in distinguishing each type of secondary changes that occur in leiomyomas. Various degenerative changes occur in approximately 65% of uterine leiomyomas, and are caused mainly by alteration in the blood supply originating from rapid growth, pregnancy, mechanical accident, and postmenopausal atrophy. These changes include hyaline, mucoid, or myxoid degeneration, calcification, cystic changes, necrosis (red degeneration), and fatty metamorphosis. It is well known that the presence of degenerative changes within leiomyomas can be predicted on MR imaging by a heterogeneous signal intensity on T2-weighted images, although clear distinction of each type of degeneration can not be made by this modality. Recently, cellular leiomyoma, one of the variants of leiomyomas, was also reported to cause heterogeneous signal intensity. However, because various other uterine tumors can also have similar signal intensity on MR imaging, further evaluation for the heterogeneous leiomyomas appears to be necessary. The purpose of our study was to analyze the patterns of heterogeneous leiomyomas and to differentiate each type of secondary changes by means of MR imaging-pathologic correlation.