<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019f4883-5141-7111-8fd4-8e2e7db96755,g:364b79b3-3ce9-4b2c-ab6b-b12a6d42f5f1-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:roleRef roleURI="http://www.ngsgi.com/role/CoverPage" xlink:type="simple" xlink:href="ngs-20260612.xsd#CoverPage"/>
  <link:presentationLink xlink:role="http://www.ngsgi.com/role/CoverPage" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CoverAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019f4883-5141-7c70-88e7-657f9105ec7d" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentType"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_DocumentType_019f4883-5141-7c70-88e7-657f9105ec7d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019f4883-5141-7baa-a92d-7274a3cedb78" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentPeriodEndDate"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_DocumentPeriodEndDate_019f4883-5141-7baa-a92d-7274a3cedb78" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019f4883-5141-7f80-be53-55d875456739" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityRegistrantName"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_EntityRegistrantName_019f4883-5141-7f80-be53-55d875456739" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019f4883-5141-72d4-ae2c-cf15d1a9a6cf" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019f4883-5141-72d4-ae2c-cf15d1a9a6cf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019f4883-5141-768d-b699-f40eb9d3ca22" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFileNumber"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_EntityFileNumber_019f4883-5141-768d-b699-f40eb9d3ca22" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019f4883-5141-7261-be74-861bf1876d05" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_EntityTaxIdentificationNumber_019f4883-5141-7261-be74-861bf1876d05" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019f4883-5141-7aaa-b6cb-77abb980eae3" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressAddressLine1"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_EntityAddressAddressLine1_019f4883-5141-7aaa-b6cb-77abb980eae3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019f4883-5141-73ca-8001-971eb9d329b9" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressCityOrTown"/>
    <link:presentationArc order="8" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_EntityAddressCityOrTown_019f4883-5141-73ca-8001-971eb9d329b9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019f4883-5141-7c27-b6ab-dbd9e712147d" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressStateOrProvince"/>
    <link:presentationArc order="9" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_EntityAddressStateOrProvince_019f4883-5141-7c27-b6ab-dbd9e712147d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019f4883-5141-712b-aac0-865ee010c535" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressPostalZipCode"/>
    <link:presentationArc order="10" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_EntityAddressPostalZipCode_019f4883-5141-712b-aac0-865ee010c535" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019f4883-5141-7fd3-89fe-a40565c3d3be" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CityAreaCode"/>
    <link:presentationArc order="11" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_CityAreaCode_019f4883-5141-7fd3-89fe-a40565c3d3be" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019f4883-5141-7b37-96ed-cedba559edf8" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LocalPhoneNumber"/>
    <link:presentationArc order="12" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_LocalPhoneNumber_019f4883-5141-7b37-96ed-cedba559edf8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_WrittenCommunications_019f4883-5141-7d70-a509-c6c8ee0ff18f" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_WrittenCommunications"/>
    <link:presentationArc order="13" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_WrittenCommunications_019f4883-5141-7d70-a509-c6c8ee0ff18f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SolicitingMaterial_019f4883-5141-7f51-a094-b141b79e398e" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SolicitingMaterial"/>
    <link:presentationArc order="14" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_SolicitingMaterial_019f4883-5141-7f51-a094-b141b79e398e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementTenderOffer_019f4883-5141-7b76-9633-63390273ea11" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_PreCommencementTenderOffer"/>
    <link:presentationArc order="15" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_PreCommencementTenderOffer_019f4883-5141-7b76-9633-63390273ea11" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementIssuerTenderOffer_019f4883-5141-721f-9ede-4b7262f0a9e4" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_PreCommencementIssuerTenderOffer"/>
    <link:presentationArc order="16" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_PreCommencementIssuerTenderOffer_019f4883-5141-721f-9ede-4b7262f0a9e4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019f4883-5141-79ac-a62f-b4d23524abad" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_Security12bTitle"/>
    <link:presentationArc order="17" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_Security12bTitle_019f4883-5141-79ac-a62f-b4d23524abad" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019f4883-5141-7522-87a5-f1004dbeb45a" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_TradingSymbol"/>
    <link:presentationArc order="18" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_TradingSymbol_019f4883-5141-7522-87a5-f1004dbeb45a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019f4883-5141-705e-a297-6711e726e2d4" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SecurityExchangeName"/>
    <link:presentationArc order="19" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_SecurityExchangeName_019f4883-5141-705e-a297-6711e726e2d4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019f4883-5141-74af-8140-814cea09d69e" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:presentationArc order="20" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_EntityEmergingGrowthCompany_019f4883-5141-74af-8140-814cea09d69e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019f4883-5141-7e42-86c6-2d504f2a314e" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AmendmentFlag"/>
    <link:presentationArc order="21" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_AmendmentFlag_019f4883-5141-7e42-86c6-2d504f2a314e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019f4883-5141-7641-bc09-bd2ac00f95e7" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCentralIndexKey"/>
    <link:presentationArc order="22" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f4883-5141-7c49-b5db-8f1323477fdb" xlink:to="loc_dei_EntityCentralIndexKey_019f4883-5141-7641-bc09-bd2ac00f95e7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
</link:linkbase>
