Applicability of Horizontal Drilling Techniques in Iran: A Field Case Study in BiBi Hakimeh Field, Southwest Iran

Abstract

Bibi hakimeh field, one of the biggest Iranian fields tat has an important role in daily production of oil and gas, was discovered at 1961 by drilling well no. 1 and at 1964 the well starting producing oil. Stratigraphic thickness of this field is 400 meter that increases in northern direction. And it has relation with Bangestan formation. Bibi hakimeh field is an oil saturated field which has a pressure of 2263 psi and a temperature of 147*F at gas oil contact. Horizontal drilling techniques are applied for such "thin reservoir" which the vertical drilling depth is not enough. This paper investigates the applicability of horizontal drilling technique in well #74 Bibi hakimeh field that there was a need to use the horizontal drilling techniques, but this technique didn't have very good results in this field and the most horizontal wells that were drilled in this field had an equal or lower production than vertical wells. This method has advantages and disadvantages that are explained in this paper. The flow rate of vertical and horizontal wells is almost the same, but with respect to the geological structures and low reservoir thickness there was a necessity to drill horizontally. In this study the advantages and problems which horizontal drilling is dealing with area described. In addition some good data from wells that drilled horizontally in this field are available. Introduction History of horizontal well technology in Iran -In July 1992, the horizontal well drilling was started in iran by drilling Marun Well No. 199 and since 2001, 96 horizontal wells were programmed to drill. Among them, seven wells were continued in directional form, thirteen wells shifted from vertical to horizontal position and the remaining wells were drilled completely horizontally. Among drilled horizontal wells, 74 wells produce in the rate of 162 Mbbl/day and the accumulative production of these wells was 262 MMbbl. Investigations showed that there was not any difference between the producing flow rate of horizontal and vertical wells. Despite, in the following cases very good results were obtained:Ahwaz Field (Asmari)Mansori Field (Ilam)Parsi Field (Asmari)Workover wells in Asmari formation Technology of horizontal wells is applied for some "thin reservoirs" in which the vertical drilling depth is not enough. The examples of these types of reservoirs are:Bibi hakimeh reservoirNorth crest line of Ragsefid reservoir Among horizontal/directional-drilled wells, 74 wells are producing (7 directional wells and 67 horizontal wells). For one well, the wellhead equipments and pipelines were not available. Five wells didn't participate in production because they were not economical. one of them has no completed yet, so there is not any production from this well. The production from five wells stopped because of some problems that occurred during production. In December 1991, the production from horizontal wells was started by producing from Gachsaran Well No. 142. According to statistics of production in June 2001, horizontal wells produced 5% of cumulative production of total wells. Cumulative production of horizontal wells was 228.7 MMMbbl and seven wells were completed with 13000 bbl/day and the cumulative production was 33.386 MMbbl. Most of the wells were medium radius that their hole diameters were between 41/8" and 81/2". Among four techniques of horizontal well completion in the world, two techniques of "Open hole completion" and "Perforated liner" were used in Iran Most the horizontal drillings are located in Asmari and Bangestan formations and from this time on, in nine fields (11 reservoirs), horizontal drilling technique, are applied. All of the horizontal wells were drilled in carbonate-naturally fractured reservoirs, except one well. Approximately 50 percent of all drilled horizontal wells have not reached the target. Major problems were:

Analytical Fractured Reservoir Characterization by using Geological and Petrophysical Logs

“…The structural style of the fields located in the southern basin of Iran is quite complex due to compression along the northern edge of the Arabian plate marked by the Zagros Mountain belt of 200-300 km width (Fig. 1 and 2) (Kalantari-Dahaghi et al, 2006).…”