Application of a Novel Open-Hole Horizontal Well Completion in Saudi Arabia

Abstract

Horizontal completion technology has progressed dramatically over the last six years, with the latest technical barriers being eclipsed with open-hole technology. These completions have allowed multiple zones to be fractured and the benefits of utilizing open-hole horizontal completion technology have been well documented. The efficiencies and benefits of utilizing open-hole completion with mechanical isolation, has lead to the operational benefits of multiple fracturing operations being pumped in one continuous operation equating to time savings, more efficient fractures, faster cleanup and less safety hazards. Conventional methods of cementing a liner in place, perforating, fracturing and repeating the process for the number of stages required can be very time consuming with added expense of removing the frac plugs with coiled tubing after the operations have been completed. When drilling a horizontal well, there are two preferred completion options. First, the horizontal section can be completed open-hole or with slotted/preperforated liner. In these completions effective stimulation along the horizontal wellbore is almost impossible. The second completion system, cased/perforated liner, requires cementing the production liner and running multiple isolation systems to effectively treat different sections of the wellbore. Multiple coiled tubing trips and multiple rig-up and rig-down of the stimulation equipment is required. These multi-stage horizontal completions take weeks to complete at high costs and elevated risks. Ultimately, the high completion costs or the lack of production due to ineffective stimulation make many reservoirs uneconomical to exploit. This paper will discuss the new completion designed specifically for open-hole fracturing of both sandstone and carbonate reservoirs. This innovative, field proven system greatly increases the effectiveness of fracturing operations by segmenting the lateral and producing mechanical isolation points in the wellbore using the high performance open-hole packers. The system allows precision placement of fracturing fluids to maximize post-fracture productivity of the well. The completion system is run as part of an uncemented liner and spaced out based on the required number of stages. Once in place the packers are hydraulically set and fracturing treatments are pumped in separate stages but as a single continuous operation. By eliminating cementing requirements, natural fractures are undamaged and easily stimulated during pumping operations. Introduction Over the last two decades many developments have enabled an accelerated growth in horizontal drilling. Current drilling technologies have pioneered these advancements to such an extent that drilling thousands of feet through a thinly bedded hydrocarbon reservoir is not a challenge anymore. While horizontal drilling has progressed over the last decade to become the field development method of choice, in many cases, there have been certain limiting technologies on the completion of horizontal wells that have proven to slow that growth. This is primarily the ability to effectively stimulate or fracture different intervals of the horizontal wellbore, particularly in reservoirs that are not naturally fractured. The use of limited entry and bullheading techniques provides little, if any, benefit compared to vertical wells. Post production analysis on the deliverability of horizontal wells in reservoirs such as matrix, heterogeneous and non-conventional formations showed a direct correlation to the completion and stimulation methods employed and their shortcomings in horizontal applications. Thus, the additional economics required to drill a horizontal well was not justified by the equal to or slightly better production results compared to vertical wells.

First Regional Selective Packerless Acid Fracture Stimulation With Coiled Tubing: A Documented Case History From Saudi Arabia

“…Al-Naimi et al, 2 reports a downhole Instantaneous Shut-In Pressure (ISIP) of 3,400 psi which one is equivalent to a fracture gradient of 0.485 psi/ft for the same formation. Al-Naimi et al, 2 reports a downhole Instantaneous Shut-In Pressure (ISIP) of 3,400 psi which one is equivalent to a fracture gradient of 0.485 psi/ft for the same formation.…”

Model of Hydraulic Fracture Initiation from the Notched Open Hole

“…This practice creates several hydraulic fractures oriented transversely to the wellbore, thus providing larger reservoir contact compared to a single longitudinal fracture. Unlike cased wells that are stimulated through perforations, in openhole stimulation, the length of treated section is defined by the spacing between packers and can vary from 100 ft to 1,000 ft (Al-Naimi et al 2008). In the case of tight and competent rock, the openhole completion of a horizontal well becomes a cost-effective alternative to a cemented completion.…”

Multiple Fracture Initiation in Openhole Without Mechanical Isolation: First Step to Fulfill an Ambition

“…Field practices and case studies indicate success in creating multiple fractures along horizontal openholes by using mechanical isolation means openhole packers (Gottschling, 2005) or sand plugs (Al-Naimi et al, 2008). These operations often involve setting packers, shifting valves or dropping balls in multiple stages.…”

“…Multi-stage stimulation treatments in horizontal wells generally target the creation of transverse fractures in order to access a much larger volume of reservoir (Fig 1), being of particular importance in lower permeability reservoirs (Rahim et al, 2011). With many wells completed openhole in competent formations (Naimi, Lee et al 2008), the ability to locate and orient hydraulic fractures can significantly impact well productivity. Orienting the lateral toward the direction of minimum horizontal stress σ h is a necessary requirement in achieving transverse fractures.…”