using (WordprocessingDocument wordDococument = WordprocessingDocument.Open(fileName, true))
                {
                    string docText = null;
                    using (StreamReader sr = new StreamReader(wordDococument.MainDocumentPart.GetStream()))
                    {
                        docText = sr.ReadToEnd();
                    }

                    //в шаблоне заменяем метки на значения
                    for (int i = 0; i < ArrayForms[listForms.SelectedIndex].Fields.Count; i++)
                    {
                        Regex regexText = new Regex("{" + ArrayForms[listForms.SelectedIndex].Fields[i].Name + "}");
                        docText = regexText.Replace(docText, DataFormDataGridView.Rows[DataFormDataGridView.CurrentCell.RowIndex].Cells[i].Value.ToString());
                    }
                    
                    //сохраняем документ
                    using (StreamWriter sw = new StreamWriter(wordDococument.MainDocumentPart.GetStream(FileMode.Create)))
                    {
                        sw.Write(docText);
                    }
                    //открывает документ
                    Process.Start(fileName);

using (WordprocessingDocument wordDococument = WordprocessingDocument.Open(fileName, true))
                {
                    string docText = null;
                    //using (StreamReader sr = new StreamReader(wordDococument.MainDocumentPart.GetStream()))
                    //{
                    //    docText = sr.ReadToEnd();
                    //}

                    FileInfo fInfo = new FileInfo(fileName);
                    using (FileStream fStream = fInfo.Open(FileMode.Open, FileAccess.Read, FileShare.Read))
                    {
                        byte[] result = new byte[fInfo.Length];
                        fStream.Read(result, 0, (int)fInfo.Length);
                        docText = Encoding.Default.GetString(result);
                    }

                    //в шаблоне заменяем метки на значения
                    for (int i = 0; i < ArrayForms[listForms.SelectedIndex].Fields.Count; i++)
                    {
                        Regex regexText = new Regex("{" + ArrayForms[listForms.SelectedIndex].Fields[i].Name + "}");
                        docText = regexText.Replace(docText, DataFormDataGridView.Rows[DataFormDataGridView.CurrentCell.RowIndex].Cells[i].Value.ToString());
                    }
                    
                    ////сохраняем документ
                    //using (StreamWriter sw = new StreamWriter(wordDococument.MainDocumentPart.GetStream(FileMode.Create)))
                    //{
                    //    sw.Write(docText);
                    //}
                    //открывает документ
                    Process.Start(fileName);