Below you'll find code snippet for reading Excel Sheet names from Office 2007 Excel document

public static List<string> GetSheetInfo(string fileName)
        {
            //  Fill this collection with a list of all the sheets.
            List<string> sheets = new List<string>();

            using (Microsoft.Office.DocumentFormat.OpenXml.Packaging.SpreadsheetDocument xlPackage = Microsoft.Office.DocumentFormat.OpenXml.Packaging.SpreadsheetDocument.Open(fileName, false))
            {
                Microsoft.Office.DocumentFormat.OpenXml.Packaging.WorkbookPart workbook = xlPackage.WorkbookPart;
                System.IO.Stream workbookstr = workbook.GetStream();
                System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
                doc.Load(workbookstr);

                System.Xml.XmlNamespaceManager nsManager = new System.Xml.XmlNamespaceManager(doc.NameTable);
                nsManager.AddNamespace("default", doc.DocumentElement.NamespaceURI);
                System.Xml.XmlNodeList nodelist = doc.SelectNodes("//default:sheets/default:sheet", nsManager);

                foreach (System.Xml.XmlNode node in nodelist)
                {
                    string sheetName = string.Empty;
                    sheetName = node.Attributes["name"].Value;
                    sheets.Add(sheetName);
                }
            }
            return sheets;
        }