| Popis: |
When performing hydraulic fracturing treatments, the completion community widely recognizes that if the perforations can be oriented to the maximum principle stress plane and the shot density can be maximized accordingly, the success of the fracture treatment will be much greater. These benefits result from the lower breakdown pressure and the minimal tortuosity effects experienced during the process when the above conditions are met. Also, if the perforations are oriented in the maximum principle stress plane for a naturally completed, cased, and perforated well, the resulting perforation tunnels will usually be more stable than other perforations that are placed away from this preferred stress plane. In natural completion scenarios, oriented perforating becomes especially important if 1) the formation integrity is questioned, and 2) sustained production without the mobilization of sand that could impact production is challenged. Normally, when faced with this dilemma, operators have automatically defaulted to a conventional sand-control treatment to ensure that production is not interrupted and that costly well interventions to clean out wellbore sand accumulation will not be required. While traditional sand control methods; i.e., installation of screens, proppants, and completion fluids used in the completion, are capable of controlling unwanted sand production; significant productivity penalties are often experienced with their use. Now, there is another viable sand-control option that can be considered by the industry. If the completion is a candidate for sand management, a gravity-force-oriented perforating strategy, which will eliminate traditional sand control treatments, can be planned. Since the system relies on gravity for proper orientation, the most important consideration for using this concept is that the wellbore under consideration must have a minimum deviation of 25 degrees to orient to maximum principle stress or the overburden gradient. The new perforating system was used in a North-Sea field and resulted in a 37,600 BOPD sand-free production rate. The new gun system can be conveyed on wireline or coiled tubing and can also be used in conventional tubing-conveyed perforating (TCP) applications. |
