Optimization of well pad design and drilling - well clustering

A model accounting for more than 30 parameters of drilling projects, and a computer program to enumerate groupings of the wells of a pad with consequent calculations of technical-economic characteristics, are developed and tested. Seven drilling scenarios for a 24-well pad with different starting oil flow rates for the wells are studied. Optimal well groupings in terms of Net Present Value (NPV) for three discount rates and five oil production decline rates have been found. The results show that: NPV-maximizing well pad designs with unequal (varying) numbers of wells in groups (clusters) may require only slight alterations of existing designs (changing the configurations of a couple of well clusters); relative NPV gain is inversely proportional to the absolute value of NPV; observed increases in NPV in groupings with varying numbers of wells reach up to 1% with respect to groupings with equal (constant) numbers of wells in groups for conventional projects, and could reach 2% and more for shale formation development projects, and up to 45% for marginal projects

Wettability of quartz surfaces under carbon dioxide geo-sequestration conditions. A theoretical study

The wettability of rocks under reservoir conditions is important to ensure and secure long term underground storage of carbon dioxide. The composition of those rocks vary significantly and are influenced by the fact that quartz is the second most abundant mineral in the earth\u27s continental crust. Thus, the CO2 wettability of quartz dominates the overall CO2 trapping performance of storage and cap rocks. If depleted oil or gas reservoirs are used for storage of CO2 quartz surfaces of rocks in reservoirs which have been previously exposed to hydrocarbons might be covered with chemisorpt hydrocarbon molecules. The CO2 wettability of these chemically modified quartz is studied in this work with molecular dynamics. To model quartz surfaces with chemisorpt hydrocarbons both CLAYFF and DREIDING force fields are coupled at atomic site charge level using the density functional theory and the Bader charge analysis. Augmented with modified charges of the OC bond, CLAYFF and the DREIDING force fields are applied to solve the practical problem of calculating the contact angle of a water droplet on alkylated quartz surfaces in a CO2 environment. A systematic computational study of wettability of fully hydroxylated and alkylated (001) -quartz surface in carbon dioxide atmosphere with respect to surface concentration of pentyl groups is performed. Alkylated quartz surfaces have been shown to be extremely hydrophobic even when the surface density of hydroxyl groups is close to the highest naturally observed. The study also verifies that a comprehensive description of wettability of alkylated quartz surface requires three parameters: the theoretical contact angle, the apparent contact angle and the hidden contact angle. These contact angles are determined at the tip level of pentyl groups and the level of the quartz surface. The hidden contact angle is calculated as the angle of a water skirt , which is formed between the level of the quartz surface and the tip level of pentyl groups. Additionally, the concept and the method of how to determine computational contact angles of a liquid droplet resting on a solid surface from individual snapshots of molecular dynamics simulations have been formulated, implemented and analysed in this work. Spherical coordinates to circumscribe a sphere around given configuration of water molecules form the basis of the method, which is thus natural and consistent with the droplet\u27s geometric computational framework

Agile methodology of well pad development

© 2020, The Author(s). Placing of wells in clusters with unequal number of thereof is an emerging concept of well pad development which still requires scrutiny even from a theoretical standpoint. The concept has its potential in improving economic efficiency of one of the most capital intensive processes in upstream sector of petroleum industry—the well pad drilling. To advocate and strengthen this profitability enhancing potential, this work integrates clustering of unequal number of wells into modern project management methodologies (agile project management), which has not been done before. It is shown that such symbiosis, which is called here the adaptive well pad development (or agile methodology of well pad development), has twofold benefit consisting of (1) managing of and accounting for uncertainties of real projects and (2) further improving economic performance of development projects in comparison with standalone well pad configurations with unequal number of wells. To exemplify these advantages, detailed simulations of well pad drilling projects were performed with equal and unequal number of wells in clusters. The simulation model accounting for more than 40 parameters and individual features of wells shows that combination of unequal well clustering configurations with adaptation of well pad designs to updates in project parameters results in significant improvements to the net present value (NPV). For three drilling scenarios studied in this work, the NPV increments ranged from 8 to 36%. Additionally, it was found that groupings with unequal number of wells consistently outperform groupings with equal number of wells in uncertain conditions, and NPV improvements from 10 to 20% have been obtained. These findings enrich understanding of the vast space of clustering schemes with unequal number of wells and demonstrate how these well pad configurations can be applied to use ever-changing environment to one\u27s advantage. On basis of this computational study, it is now valid to assert with high degree of certainty and confidence that industrial deployment of clustering with unequal number of wells in combination with proper organizational measures results in boost to the NPV of well pad development projects at the level of several to tens of percent

Application of the CLAYFF and the DREIDING force fields for modeling of alkylated quartz surfaces

To extend applicability and to overcome limitations of combining rules for nonbond potential parameters, in this study, CLAYFF and DREIDING force fields are coupled at the level of atomic site charges to model quartz surfaces with chemisorpt hydrocarbons. Density functional theory and Bader charge analysis are applied to calculate charges of atoms of the OC bond connecting a quartz crystal and an alkyl group. The study demonstrates that the hydrogen atom of the quartz surface hydroxyl group can be removed and its charge can be redistributed among the oxygen and carbon atoms of the OC bond in a manner consistent with the results calculated at the density functional level of theory. Augmented with modified charges of the OC bond, force fields can then be applied to a practical problem of evaluation of the contact angle of a water droplet on alkylated quartz surfaces in a carbon dioxide environment, which is relevant for carbon geo-sequestration and in a broader context of oil and gas recovery. Alkylated quartz surfaces have been shown to be extremely hydrophobic even when the surface density of hydroxyl groups is close to the highest naturally observed density of 6.2 OH groups per square nanometer

Analysis of individual molecular dynamics snapshots simulating wetting of surfaces using spheroidal geometric constructions

Accurate characterization of wettability of minerals is important for efficient oil recovery and carbon geosequestration. In studies where molecular dynamics simulations are used to compute the contact angle, emphasis is often placed on results or theoretical details of the simulations themselves, overlooking potentially applicable methodologies for determination of the contact angle. In this manuscript, a concept of a method utilizing spheroidal geometric constructions to estimate the contact angle of a water droplet on a silica surface in carbon dioxide atmosphere is outlined and applied to the final snapshots of two molecular dynamics simulation runs. Two carbon dioxide pressures and two wettability modes (hydrophilic and hydrophobic) are examined to assess the method’s performance. The most stable 6-membered ellipselike rings (001) pristine surface of alpha-quartz is reconstructed using molecular dynamics and its wettability is then investigated for the first time. The outcomes of the calculations are compared with results produced with the isodensity chart method, and good agreement with the latter approach is demonstrated. The proposed method can be used as an alternative, or in conjunction with other techniques, to increase the confidence in contact angle estimations via molecular mechanics calculations. Reliable contact angle estimations, on the other hand, can guarantee accurate storage capacity and security of carbon capture and storage projects

Wettability of fully hydroxylated and alkylated (001) α-quartz surface in carbon dioxide atmosphere

Wettability of alkylated quartz surfaces is of primary importance in several technological applications, including the development of oil and gas reservoirs and carbon geo-sequestration. It is intuitively understood and experimentally confirmed that hydroxylated quartz surfaces are hydrophilic. By gradually saturating a hydroxylated (001) α-quartz surface with pentyl groups, we show using molecular dynamics simulations that the surface can also exhibit extreme hydrophobicity. Within a range of surface pentyl group density from 0.29 to 3.18/nm2, the contact angle of a water droplet under 10 MPa pressure of carbon dioxide at 300 K changes from 10–20 to 180°. This study has shown that a complete description of wettability of alkylated quartz surfaces requires three contact angles—one at the tip level of pentyl groups and two at the level of the quartz surface. The latter two are the contact angle of the spherical droplet and the hidden contact angle of a water “skirt” formed between the tip level of pentyl groups and the quartz surface. Analysis of the hidden contact angle unveils a binary wettability, where the surface relatively abruptly transforms from hydrophilic (the contact angle is less than 90°) to hydrophobic (the contact angle is 180°) with an increase in surface pentyl group concentration

Prospects of Enhancement of the Fulfilment Order of Customs Operations Connected with the Development of a Unified Automated Information System of Customs Bodies

The speed of fulfilment of customs operations is one of the main criteria of the efficiency of customs bodies’ activity. Now the Government of the Russian Federation and the Federal Customs Service of Russia conduct systematic work directed on the acceleration of customs operations related to the movement of goods through the customs borders of the Eurasian Economic Union and their further placement under customs procedures requested by customs applicants. One of the directions of acceleration of customs operations is the reduction of the number of documents submitted by the participant of foreign trade activities for the fulfilment of customs formalities. The main tool for the solution of the specified goal with preservation of customs control efficiency is the development of a unified automated information system of customs bodies and its subsystem, a system of interdepartmental electronic interaction, aimed at the interaction with other federal executive authorities. Active work on the organisation of interdepartmental interaction in custom bodies was begun in 2012. This interaction is carried out through the development and agreement of Technological Maps of Interdepartmental Interaction (ТMII). There had been developed 65 TMII by the end of 2015. Thus, the possibility of obtaining of almost all permissive documents issued by other executive authorities in electronic form is implemented. However there remains a large percentage of unanswered inquiries so far. Such a negative statistic is caused mostly by two reasons: the peculiarities of TMII development and the absence of answers to the requests for permissive documents issued by the bodies of other countries of the Eurasian Economic Union. These problems can be solved by the deployment of the integrated information system of foreign and mutual trade of the Customs Union in the nearest future as well as the improvement of the existing TMII. Another option is the introduction of a mechanism of customs control based on the end-to-end process using a unified software product

Impact of Risk Supply Chain Management and International Debt Market Indicators on GDP

Financial and economic globalization has significantly increased the total amount of external debt of the different countries of the world. An aggravation of the problem of globalization of the external debt prevents the restoration of stability and achieving sustainable growth in the current global economy. In this regard, at present various countries and groups of countries strengthen management of external borrowings at the national and regional levels. The author has made an attempt to evaluate an impact of the major international debt market indicators and risk supply chain management on GDP. The paper is focusing on an econometric analysis of the hypothetical linkage between the major international debt market indicators and risk supply chain management on GDP growth. A correlation and regression analysis was applied as the basic method of econometric study. The paper has a conclusion that in the world the most effective external debt instruments stimulating the growth of GDP are international syndicated loans and gross issues of international debt securities

Tissue Specificity of Exosomes and Their Prospects as a Drug Delivery System

This chapter reviewed the various sources of exosomes and their characteristics. Exosomes, which in the context of the proposed chapter are the synonym for extracellular vesicles up to 200 nm, play a pivotal role in cell to cell communication thus leading to the involvement of exosomes in inflammation and cancer development. This brings exosomes to the forefront of promising markers of a sub-clinical stage of the disease, which makes identifying exosome’s source and destination one of the main goals in exosome research. However, due to some biogenesis features and technological difficulties, which are discussed further, identification of a certain exosome’s address, or its specificity for a certain tissue or cell type, becomes a non-trivial task. The chapter covers the following questions: some of the main barriers on the way of testing tissue specificity hypothesis of exosomes, exosomes from synovial fluid and CSF and their features, exosomes from mesenchymal stem cells (MSCs) of different origins, and some membrane and cargo exosomal markers for tissue specificity and the prospect of exosomes as a drug delivery approach

miRNAs in Liver Cancer

miRNAs are small noncoding RNAs, which are involved in epigenetic regulation of gene expression. Hepatocellular carcinoma (HCC), although not being at the top of most widespread cancers, nevertheless, remains among cancers with the most lethal cases. The chapter is dedicated to the epigenetic aspect of HCC development, namely the role of miRNA in this process. Being small and noncoding RNAs, they have a huge and significant function in gene regulation. This chapter will briefly cover following questions: miRNA biogenesis and function, metabolic and signaling pathways disrupted in HCC with a significant miRNA involvement, and main miRNAs contributing to HCC development and their targets