Online assessment: part 1 is competency based questionnaire, 18 questions, which can be found on scribd.com; part 2 consists of two parts, part 1 is decision-making tests, part 2 is numerical test, which can be tricky at the beginning, you can best practice them on jobtestprep.
Next round is telephone interview based on the CAR categories of Shell, all the questions can be found on glassdoor, most important is that you must prepare a lot of stories which can be used for answering those questions.