| Popis: |
The Furrial Field located in the Eastern Basin of Venezuela is characterized by large oil reservoirs with complex geology due to faulting and heterogeneity. To optimize oil production and oil recovery in the field, the operator, PDVSA, implemented a gas-injection project. Several wells were drilled and completed as cased-hole completions using through-tubing and casing-gun technology. However, the results obtained with the conventional perforating techniques yielded less than optimum injectivity indices, non-uniform injection profiles, and higher compression requirements on the gas injectors. The primary damage mechanism in these completions was identified as asphaltene deposition, presenting the challenges of being able to identify the damaged zones, and then, to selectively treat them in a safe and economical method under the prevailing conditions. Another problem identified was the emulsion damage caused by the inverted mud system used during drilling operations. After review of the available perforation and stimulation methods, a propellant high-energy gas fracturing technique was selected for field trials to enhance injectivity. The propellant high-energy gas fracturing technique, although not a new technology, was the first application of this process on gas injectors in Venezuela. This paper emphasizes the methodology used to validate the application of the propellant high-energy gas fracturing technique on gas-injection wells and the use of surfactant during propellant activation to further creating an additional stimulating effect in the formation. A computer simulator was used to design the propellant treatments and analyze the effects of generated pressures on the mechanical well configuration and wireline design. The primary benefit of propellant treatments is its capability to selectively create mild fracturing with minimal formation damage. This benefit was demonstrated with the improvements and changes obtained in the injectivity and productivity profiles. The case histories from the Furrial field validate this technology and provide operational guidelines and results in the form of injectivity changes. Production log responses to evaluate effectiveness of selective propellant placement will demonstrate the changes in completion efficiency. The propellant high-energy fracturing technique offers a simple, cost effective, and time-saving alternative to more commonly known stimulation techniques for selective treatment of formations. The objectives of this document are to present the experience gained from applying the technique, the results obtained, and why this method was particularly beneficial to the wells included in this paper. |
