Recent improvements in fracturing technologies have allowed access to tight formations that previously were considered unprofitable. The most common of these technologies is a ball-drop-actuated sliding sleeve that allows operators to economically isolate and fracture ten to twenty zones in a single well. While these technologies have been well proven, there are still drawbacks such as:
Each zone requires a drop in the production string ID The zones must be stimulated beginning at the toe and ending at the heel Many applications require milling-out of ball seats after fracturing When possible to move sleeves after fracing, a workover is required.
A system has been developed to alleviate these limitations. This system includes well profile and isolation similar to the ball-drop sliding sleeve system but offers control of the sliding sleeves from the surface. This eliminates the cost and downtime of intervention. The system consists of an ICV (interval control valve) that has been optimized for fracturing applications. It is essentially an intelligent completion method that can withstand the extreme environment of a frac application. This allows the operator to frac the zones in any order, re-frac at a later date, close zones to allow pressure to build, eliminate water cut, and conduct transient pressure analysis of any zone without the necessity of a workover.
This paper discusses the use of surface-controlled sliding sleeves in frac-pack operations and the benefits that an operator can realize by installing the new sliding sleeves in tight formations.
A series of copolymers and blends based on polybutylene were characterized using 13C NMR and thermal analysis. Optical microscopy techniques were used to measure crystallization rates and examine their morphology, and this behavior was related to their composition. As expected, the highest melting and crystallization temperatures, and the fastest crystallization rates were obtained for the polybutylene homopolymer. Copolymerized ethylene randomly distributed along the chain, even at a level of 1 %, significantly reduced the melting temperature and crystallization rate. Increasing the ethylene content to 5 % results in a polybutylene which crystallizes with difficulty to produce poorly defined spherulites. Four blends based on a polybutylene containing 1 % ethylene were studied. A dispersed crystalline phase could be detected in all cases. Two of the blends contained 6-7% ethylene but differed in molar mass. Their *Present address: General Electric Plastics BV,
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