Evaluation of Reasonable Productivity of Horizontal Wells in Offshore Carbonate Gas Reservoirs

Abstract

1 exploration well has been drilled in the target gas field, and coring and production test have been carried out. It is planned to deploy a horizontal well in the high part of the gas reservoir for depletion development. How to evaluate the productivity of horizontal wells and determine the reasonable proration gas production has become the key to the development of the gas field. For this reason, well test interpretation was carried out and the AOF was calculated based on the dual-porosity and dual-permeability model. The reasonable proration production of horizontal wells was determined according to the formula of the productivity substitution ratio of horizontal wells to vertical wells. The condensate water production of horizontal wells was obtained based on the prediction of horizontal well production and the WGR calculation result. The research result indicates that the target interval has a formation pressure of 897 pisa, an effective permeability of 175 mD, and a formation coefficient of 17000 mD.ft, showing medium-high permeability reservoirs; in addition, the AOF of the test well is 44.32 MMscfd. Based on the productivity substitution ratio formula, when the horizontal length is 600 m, the corresponding productivity substitution ratio is 2.15. The proration production of the gas field in the research area is 1/3 of the AOF, and then the reasonable proration production of a horizontal well is 31.7 MMscfd.