// Create Woocommerce Custom Field (here called Base Name)
add_action( 'woocommerce_product_options_general_product_data', 'woo_add_custom_general_fields' );
function woo_add_custom_general_fields() {

  global $woocommerce, $post;
  echo '<div class="options_group">';

  // Make our text field with the following
  	woocommerce_wp_text_input(
		array(
			'id'          => 'base_name',
			'label'       => __( 'Base Name Field', 'woocommerce' ),
			'placeholder' => 'base name text here',
			'desc_tip'    => 'true',
			'description' => __( 'Enter the custom value here.', 'woocommerce' )
			)
	);

  echo '</div>';

}
// Save to the wpbd when we update the product pages (post)
add_action( 'woocommerce_process_product_meta', 'woo_add_custom_general_fields_save' );
function woo_add_custom_general_fields_save( $post_id ){

	$woocommerce_text_field = $_POST['base_name'];  	// Text Field
	if( !empty( $woocommerce_text_field ) ) update_post_meta( $post_id, 'base_name', esc_attr( $woocommerce_text_field ) );

}