Technical measures of deliverability enhancement for mature gas fields: A case study of Carboniferous reservoirs in Wubaiti gas field, eastern Sichuan Basin, SW China

Abstract

Taking the carboniferous reservoir of Wubaiti gas field in eastern Sichuan Basin as an example, the technology strategies are proposed about the following major problems during the middle to late stage of gas field development: imbalance development, low permeability and low efficient reserves left with low producing degree, unreasonable proration caused by changes of gas well dynamic productivity, universal water production in gas wells, high reserve recovery and composite decline rate of reserve-rich region, and lack of new methods for reserves producing evaluation and remaining reserves distribution prediction. The development technical strategies for Wubaiti gas field are as follows: (1) stratigraphic subdivision and structural description in which fault and tectonic fluctuations are describe based on seismic interpretation data; (2) division and quantitative characterization of reservoir units in which the reservoir shape, scale, connectivity and gas-bearing range are evaluated according to dynamic and static data; (3) fluid distribution and dynamic response analysis in which gas-water distribution pattern is figured out by combining structure, reservoir and gas well production dynamic characteristics; (4) reserves producing degree evaluation and deliverability review in which reserves producing degree and remaining recoverable reserves scale are evaluated from the perspective of static geological reserves and dynamic reserves, to make clear the direction of the next step production and establish rational production system in the late stage; (5) static geological model establishment and dynamic correction in which gas reservoir pressure and remaining reserve distribution are predicted by using fine 3D geological modeling and numerical simulation; (6) remaining reserves prediction and classified evaluation based on the dynamic revision prediction model to guide the recovery of remaining reserves; and (7) gas production technology and equipment development, targeted gas recovery techniques are provided concerning the mature gas field. Key words: eastern Sichuan Basin, Wubaiti gas field, reservoir description, gas field development, remaining reserves, deliverability enhancement, technical strategies