| Jiannan Natural Gas Field lies in western Hubei province or eastern Chongqing City. The main reservoir of the gas field, Feisan sections of Feixianguan group in triassic system, owns explored geological reserves of 65.24×10~8m~3, and belongs to carbonate rock gas reservoir with low porosity and low permeability. The poor reservoir physical properties, small single-well control area, low reserve grade and great production difficulties made it impossible to reach industry production scale without stimulation before completion. In 2002 the head office of SINOPEC entrusted settling the technology problems of Jiannan Gas Field to Jianghan Oil Field. Based on sufficient literature investigation on gas reservoir development and reservoir geological study of Feisan sections of Jiannan Gas Field during three years, reservoir sensitivity was evaluated, study on laboratory test and design optimization of acidizing fracturing was implemented, and with continuous field practices the acidizing fracturing technology was gradually improved and developed for Feisan sections of Jiannan Gas Field. Following technologies are discussed in this paper.(1).Reservoir geological study: Reservoir subdivision, reservoir comprehensive evaluation, and fracture prediction was implemented for Feisan sections of Jiannan Gas Field, which provides strong foundation for subsequent formation protection and stimulation.(2).Laboratory test: By laboratory testing of acid-rock reaction rate constant, hydrogen ion mass transfer coefficient and acid-rock reaction activation energy parameters, acid-rock reaction dynamic formula was established, which makes the acid-rock reaction dynamic theories guide the field practices more feasible.(3).Laboratory study of acidizing fracturing technology: Bulk acid formula of acidizing fracturing was developed, and property evaluation was performed. Study on wormhole fracture conductivity tests and acidizing fracturing simulation tests were conducted. Field job programs and reacted acid flow back technology were established for acidizing fracturing, which made a good technical preparation for subsequent field application.(4). Design optimization study: physical and mathematical model were built to simulate actual stimulation procedure to establish the optimized design and provide guideline for field application.(5). Field application of acidizing fracturing technology: Field application results were discussed with statistics. Typical well cases were analyzed to conform compatibility of the acidizing fracturing technology. |
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