The Productivity Estimation of Designed Horizontal Oil and Gas Wells Before a Drilling Operation, Using Seismic and Petrophysical Parameters and Modeling

Abstract

For feasibility studies of field development projects and management of time, risk, and cost, it is crucial to forecast the productivity of oil and gas wells. In this research a precise and comprehensive methodology is presented to estimate productivity in horizontal drilling.

Petrophysical parameters of one of the Iranian oilfields including effective porosity, clay percentage, water saturation, and permeability were investigated in horizontal and vertical sections with specific intervals in all the reservoir spots using the well logging data. The seismic parameters of the reservoir including frequency, amplitude, and phase of the reflected seismic waves were also investigated.

Petrophysical Reservoir Hydrocarbon Potential Index (RHPi)_p and Seismic Reservoir Hydrocarbon Potential Index (RHPi)_s were obtained by the combining of the petrophysical and seismic parameters, respectively. The former index cannot solely represent the hydrocarbon quality of the reservoir precisely. In ideal condition, the two indices must be equal for a specific section of the reservoir.

Another index, the Average Reservoir Hydrocarbon Potential Index (RHPi)_av, which is actually the average of the aforesaid indices, was defined. This index ensures high accuracy. By applying and generalizing (RHPi)_av to the whole reservoir, another index known as the Well Efficiency Index (WEI) was obtained. This index can be used to estimate and correct the productivity of the designed horizontal wells before drilling, comparing actual productivity of vertical wells drilled in the oilfield.

The result is a range of productivity with a particular safety factor that has a high degree of accuracy and precision.

Keywords:

• horizontal well
• hydrocarbon potential index
• petrophysical parameter
• productivity estimation
• seismic
• well efficiency index (WEI)