Gas Horizontal Well Productivity In The Study

Sulige gas field, one of the main natural gas production base of Changqing oil field, have more than530billion cubic meters proved reserves. However, the low permeability, dispersed small single sand, serious heterogeneity, low abundance and low single well control reserve result in slow recovery of shut in pressure after gas well production test, low production, poor capability of stable production, low recovery of the overall gas field and other unfavorable situation of development. In order to improve the single well controlled reserves and production, improve the recovery and economic efficiency of the overall gas reservoir, the technology of horizontal wells were widely used and development, which make the annual yield of Sulige gas field approach15billion cubic meters in2011.The special law of horizontal well percolation in lithologic gas reservoir and the sheer difficulty of stable well testing result in the sheer difficulty of accurately determining the productivity of horizontal gas well. Then how to determine the productivity of horizontal gas well simply, quickly and accurately on the premise of an invalid systematic productivity test becomes a focus of attention. This thesis, the typical block of Sulige gas field as the research object, carried out evaluation of horizontal well productivity, achieved the corresponding results.1. Conventional horizontal well productivity equation does not apply to Sulige lithologic gas reservoir. The percolation characteristics of horizontal well similar to vertical well when they reach the quasi-steady flow stage, by analyzing and comparing the percolation characteristics of vertical well and horizontal well. So the productivity analysis method of vertical well can be used for reference when analyzing the horizontal well productivity of Sulige lithologythe gas reservoir.2. The influence degree of reservoir permeability, thickness, horizontal length, skin factor, sand body size and pressure cracks on horizontal well productivity were researched.3. The series of steady state analysis and test design method have been taken to study the time when the horizontal gas well percolation come into the quasi-steady stage and made a test time sensitivity analysis with the length of the horizontal section, gas layer thickness, permeability, porosity, location of horizontal well and the shape of gas reservoir boundary.4. Established the single influencing factor plate and single-point productivity formula to determine the horizontal well productivity. The stable test data of20horizontal wells were selected to verify the single-point productivity formula in this thesis, by drawing lessons from single-point productivity formula of vertical well and using the formula obtained by few horizontal wells.The results showed that the error of the single-point productivity formula obtained in this thesis was very low, it proved that this method can be used to determine the productivity of horizontal wells in Sulige lithologic gas reservoir.