Optimizing Choice of Horizontal Well Borehole Profile Design

By Pavel Korchagin, Alexander A. Okhotnikov, Alexander B. Okhotnikov , June 10, 2014

Today, one of important goals for oil and gas companies operating in competitive envirionment is to reduce costs of well drilling. One of the most perspective ways to accomplish that goal is to optimize well borehole profiles.

ERIELL Group specialists completed a series of operations that aimed to study the properties of horizontal well borehole profiles in order to develop the kind of methodology of borehole profile design that would ensure minimal costs of well construction. 

Ultimately, the work on solving this problem was split into several stages:

  • Development of a method of profile calculation, with the minimum borehole length;
  • Study of impact of intensity of deviation at sections where angle buildup (slidedown) occurs along the length of the borehole;
  • Study of influence of angle of entry into the reservoir along the length of the borehole;
  • Identification of optimum combination of deviation intensities at sections of angle buildup (slidedown);
  • Identification of the optimum angle of entry into the reservoir.

Below you can see the results we achieved while solving this task:

At the Samburgskoye field we conducted tests to identify the impact of deviation intensity change at sections of angle buildup (slidedown) related to the change of the casing string depth and the depth of the entire well. Numerous horizontal well borehole profiles (180 different versions) were used as benchmark data. While calculating numerous profiles, well deviation and deviation intensities at first and second section of angle buildup (slidedown) and deviation intensity of angle buildup at the point of entry into the reservoir were used as independent (controlled) variables. When creating numerous profiles, certain limitations are placed on independent variables – the maximum value of deviation intensity at angle buildup (slidedown) sections shouldn’t exceed 2.5 degrees per 10 meters, the while the minimum value shouldn’t top 0.35 degrees per 10 meters and the angle of entry into the reservoir should range between 71.38 and 83.44 degrees. 

The study resulted in identifying a number of patterns and functional dependencies that characterize the impact of afore-mentioned independent variables in terms of change of depth of casing string and the measured depth of the well.

Figure demonstrates the difference between values of measured depth of the well and types of profile, showing maximum and minimum measured depths and corresponding and the profiles with different deviation from the borehole depending on deviation intensity at different angle buildup (slidedown) sections. The value of these differences demonstrates how much the measured depth of a horizontal well could be reduced by an optimum choice of deviation intensity at angle buildup (slidedown) sections.

Another figure demonstrates the difference between values of measured depth of the well and types of profile, showing maximum and minimum measured depths and corresponding and the profiles with different deviation from the borehole depending on the angle of entry into the reservoir. The value of these differences demonstrates how much the measured depth of a horizontal well could be reduced by an optimum choice of deviation intensity at the section of entry into the