Abstract

As oil and gas reserves are declining, operators all over the world are now being forced to go to land areas with extreme conditions and deeper into the sea to find more reserves. The reservoirs are getting more complex and well designs are becoming more complicated and costly. The complex reservoirs and extreme conditions require several individual zones to be completed and fractured individually to access maximum reservoir and get the biggest return for the money. Oftentimes, each zone requires a specifically designed fracturing treatment to effectively treat it. A lot of money and time are lost each year when operators try to treat these multizones using conventional techniques. The optimum production rates are not achieved and the reservoir-recovery factor is low, leaving most of the oil and gas unrecovered.

Because of the recent drop in oil and gas prices, cost, time, and production are the driving factors causing operators to look for alternate completion and fracturing methods to reduce cost and time without compromising production. Numerous techniques and hit-and-trial methods have been tried throughout the past decade to overcome this problem. Multistage fracturing has offered one of the best solutions to everyone in this tough economic environment. Throughout the past few years, there has been a growing acceptance among both operators and service companies that hydra jet (abrasive jetting) perforating can improve overall well economics for fracture-stimulated wells in many reservoirs. More and more customers all over the world are now using multistage fracturing to access the complex reservoirs and treat wells with complex completions. In a few cases, pinpoint stimulation has proven to be the only way that effective stimulation could be achieved. The pinpoint-stimulation portfolio has evolved throughout the past decade to offer several options to different well conditions and types.

This paper presents a detailed review of many pinpoint-stimulation technologies that have been successfully used for treating multizones in complex reservoirs and extreme well conditions in the last decade, either in new wells or in mature fields, to improve the production and reservoir recovery factor. It provides insight to strategies of how these different technologies were applied to different well conditions. Case histories are provided to support the obtained benefits and advantages, and lessons learned are discussed along with recommendations and what to avoid in field operations. Future directions of pinpoint stimulation are also discussed.

Multistage fracturing can be performed in different ways, depending on the well design and completions. More and more customers are now designing the well and selecting completions based on the multistage fracturing technique that best accesses the reservoir efficiently. The following multistage fracturing techniques are discussed in this paper:

  • CT applications.

  • Jointed-pipe applications.

  • Sleeve applications.

  • Perf-and-plug applications.

Globally, pinpoint-stimulation treatments have been performed on more than 6,000 wells in 18 countries. Multistage fracturing is gaining popularity in the oilfield industry with each successful treatment that is put into the ground. With the use of CT, the task of placing many cuts at multiple places is straightforward and not time consuming. For many wells needing multistage fracture stimulations, significant reductions in nonproductive time (NPT) help reduce well costs, even when more actual fracture stages are pumped. The use of more stages has often provided significant production gains and greater recoverable reserves.

In this paper, different techniques for a wide variety of applications and a review of successful evolution of multistage fracturing in the last decade are presented.

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