Abstract
A global steady increase of energy consumption coupled with the decline of conventional oil resources points to a more aggressive exploitation of heavy oil. Management decisions and production strategies for heavy oil is booming in China. Block LKQ, one of reservoir of Tuha Oil Field, is a Extra heavy oil reservoir with edge and basal ground water. From 2003 to 2005, stimulation treatment of light oil solvent on pump and fracture had seen poor production performance meanwhile insignificant primary recovery was obtained by conventional development methods available. Availability of hydrocarbon gases produced wells adjacent to other units makes a solvent injection process attractive. Therefore, the field tests on 3 wells YX1, Y101, Y102 by gas cycling injection were carried in 2005. The objective of this study was to on-site investigate the performance of the method for enhanced recovery of LKQ heavy oil field. The paper will detail the static solution test, on-situ preparation, design injection parameters, injection process, every performance round and its result evaluation. It has settled the foundation on overall development in local deep-heavy oil reservoirs.
Several experiments have been carried out and the results show that viscosity of heavy oil dissolved is decreased 97.1% by injection gas. For static miscibility test, the more gas injecting time, the wider miscible region and the higher displacement efficiency. From the experiment figure of the solvent rate gradient, it displays the dissolution rate slows down.
Then a field study was conducted to ascertain whether gas cyclic injection mode can be effectively increase field oil rate and recovery. The field test has been lasting for 2 rounds more than 3 years and more. It was obtained primary success to develop extra deep heavy oil by cyclic gas injection. Using the injection mode, the yield of wells raised 2 times to 5 times, average yield of well was up to 8 tons per day, in which the production cycle was prolonged and oil increment was more and more. It suggests that further on-situ observation will be undertaken intently so that reasonable injecting parameters are adapted to field test in a large scale.
