Working with FileStream and BLOB

Here is an example approach to your problem, if sql has access to the repository where the files are, you can do it for yourself.

static void FileStreamMethod()
    {
        /*Conecta ao SQL*/
        SqlConnection cnnSQL = new SqlConnection("Data Source=x.x.x.x;" +
                                                 "Initial Catalog=db_base_clientes;" +
                                                 "User ID=base_clientes;" +
                                                 "Password=xxxxx");
        cnnSQL.Open();

        SqlDataReader sqlDataReader = sqlCommand.ExecuteReader();

        if (sqlDataReader.HasRows)
        {
            while (sqlDataReader.Read())
            {
                /* Objeto para origem do arquivo */
                string path = @"C:\"; // EXISTE UMA COLUNA NO SQL COM OS PATHS, FAZER foreach PARA CADA PATH
                using(fileStream = new FileStream(path, FileMode.Open, FileAccess.Read)){

                    byte[] documento;
                    /*Le o binario*/
                    using( binaryReader = new BinaryReader(fileStream))
                    {
                        documento = binaryReader.ReadBytes(Convert.ToInt32(fileStream.Length));
                    }

                    try
                    {
                        //Substitua [ID] pela sua coluna de índice
                        SqlCommand sqlUpdateCommand = new SqlCommand("UPDATE SCF_DocumentoProcessoCompra" +
                                                                        "SET Documento = @documento" +
                                                                    "WHERE [ID] = @ID ", cnnSQL);

                        //Você precisa saber o tipo da coluna para escolher o SqlDbType adequado.
                        //Deixei como Image só para exemplo
                        sqlUpdateCommand.Add("@documento", SqlDbType.Image, documento.Length).Value = file;
                        sqlUpdateCommand.Add("@id", SqlDbType.Int).Value = 0 // <- Coloque aqui o seu atributo de id da linha que está lendo;

                        sqlUpdateCommand.ExecuteNonQuery();
                        sqlUpdateCommand.Dispose();

                    }
                    catch(Exeption e){
                        sqlDataReader.Close();
                        cnnSQL.Close();                            
                        throw e;
                    }
                }               

            }
        }
        else
        {
            Console.WriteLine("No rows found.");
        }

    sqlDataReader.Close();
    //Não esqueça de fechar a conexão do banco
    cnnSQL.Close();
}

DataReader does not accept 2 SQL commands on the same connection. So I did a gambiarra (since I'll only execute this once and never again) and opened 2 connections with SQL. I solved the problem like this:

static void FileStreamMethod()
    {
        /*Conecta ao SQL*/
        SqlConnection cnnSQL = new SqlConnection(@"Data Source=x.x.x.x; " +
                                                 "Initial Catalog=SCF2_HOMOLOG;" +
                                                 "User ID=xxxxxxx;" +
                                                 "Password=xxxxxxx");
        SqlConnection cnnSQL2 = new SqlConnection(@"Data Source=x.x.x.x; " +
                                                 "Initial Catalog=SCF2_HOMOLOG;" +
                                                 "User ID=xxxxxxx;" +
                                                 "Password=xxxxxxx");
        try { cnnSQL.Open(); cnnSQL2.Open(); }
        catch (SqlException ex) { Console.WriteLine(ex.Message); }

        SqlCommand sqlCommand = new SqlCommand("SELECT id_DocumentoProcessoCompra, Path_Documento " +
                                               "FROM SCF_DocumentoProcessoCompra", cnnSQL);


        SqlDataReader sqlDataReader = sqlCommand.ExecuteReader();


        if (sqlDataReader.HasRows)
        {
            while (sqlDataReader.Read())
            {
                try
                {
                    string path = @"C:\Users\Lucas Garcia\Desktop\AnexoProcesso\" + sqlDataReader.GetString(1);
                    /* Objeto origem do arquivo */
                    FileStream fileStream = new FileStream(path, FileMode.Open, FileAccess.Read);

                    /*Le o binario do arquivo*/
                    BinaryReader binaryReader = new BinaryReader(fileStream);
                    byte[] file = binaryReader.ReadBytes(Convert.ToInt32(fileStream.Length));

                    SqlCommand sqlUpdateCommand = new SqlCommand("UPDATE SCF_DocumentoProcessoCompra " +
                                                                 "SET Documento = @documento " +
                                                                 "WHERE id_DocumentoProcessoCompra = @ID", cnnSQL2);

                    sqlUpdateCommand.Parameters.Add("@ID", SqlDbType.Int);
                    sqlUpdateCommand.Parameters["@ID"].Value = sqlDataReader.GetInt32(0);
                    sqlUpdateCommand.Parameters.Add("@documento", SqlDbType.Image);
                    sqlUpdateCommand.Parameters["@documento"].Value = file;

                    sqlUpdateCommand.ExecuteNonQuery();


                    binaryReader.Close();
                    fileStream.Close();

                    Console.WriteLine("ID {1}\nBinario: {2}\nDocumento {0} armazenado no DB", sqlDataReader.GetString(1), sqlDataReader.GetInt32(0), file);
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.Message);
                }

            }
        }
        else
        {
            Console.WriteLine("No rows found.");
        }

        sqlDataReader.Close();
        cnnSQL.Close();
        cnnSQL2.Close();
    }