convertion of ObjectResult> type to int

You have to loop over the ObjectResult<T> or use ObjectResult<T>.ElementAt() to retrieve individual elements. Then you can access the int values:

ObjectResult<Nullable<int>> queryResult = query.Execute(...);

foreach (Nullable<int> result in queryResult)
   Console.WriteLine("{0}", result.Value);

You can check if a value is available using ObjectResult<T>.HasValue