Title: Optimization of Well Length for Horizontal Drilling
Author(s): Hyun Cho and Subhash N. Shah, The University of Oklahoma
Presentation: Canadian International Petroleum Conference
Location: Calgary, Alberta Canada
Date:June 6-8, 2000
Abstract: As horizontal well drilling and complementary technology develop, horizontal drilling technology has become an economic reality, and the result has been a dramatic upsurge in the number of horizontal wells being drilled. When evaluating the potential benefits of completing wells horizontally in a specified reservoir, the expected performance of the reservoir as well as the economics of drilling and completing the wells must be taken into consideration. Increase in horizontal well length increases drainage area and well construction cost for drilling and related completion as well as other factors that decrease economics of the horizontal well. However, no reliable standards are currently available that take into account for the quantitative factors necessary for the selection of well length of horizontal drilling.
Combination approach is proposed for the analysis of these factors in order to achieve overall optimized performance of a horizontal well drilling. This paper presents the methodology developed to obtain the optimum horizontal well length based on the review of the successful jobs as well as failure cases. The effects of various parameters affecting both productivity and economics of horizontal well drilling are analyzed and discussed quantitatively. The parameters involved in the analysis are: expected productivity in vertical well, reservoir characteristics (heterogeneity, natural fracture), well construction cost based on learning curve, cash flow of the project (NPV, rate of return), lease area, drainage area in vertical/horizontal well, and horizontal well interference. This paper also presents how the optimized horizontal well length can provide economic benefits for the specific reservoir conditions. Step by step calculation procedure with examples is described with sets of graphical charts developed for illustrating the relationships between various parameters. The well lengths obtained from this simulation are also compared with the published well length data. The results from the model can be used by companies to directly determine the horizontal well length with different weight values or sensitivity of each parameter.
