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 rigup 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.

A multi-well test program designed to study the gas production mechanisms of the eastern Devonian shale reservoirs was completed. Two offset wells were drilled as observation wells in Meigs County, OH. This paper presents the engineering design of the tests, data acquired, analysis techniques, and results of the analysis. The results indicated a complete anisotropic, layered reservoir system which implies directional gas flow and orientation of natural fractures. This study has provided an insight into the production behavior of reservoirs. It will aid future development of shale gas by optimizing well spacing and understanding of the gas release mechanisms of the Devonian shales.

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.

Horizontal wells with multiple fractures are becoming more prevalent in the Industry. They are especially beneficial in carbonate plays where acid and fracture stimulation can be used to improve productivity, the technique can be used for tight reservoirs and multiple compartments or anisotropic reservoirs with high permeability contrasts. Reliable evaluations of stimulation performance are required for field development planning. As such, pressure transients are often used, and can be successful, tight reservoirs where transient flow regimes can be used to observe and define the various impacting factors of stimulation, such as fracture length, conductivity, orientation, etc. This project investigates the modeling and interpretation of pressure transient responses of multiple hydraulic fractured horizontal wells (MHFHW) using a numerical reservoir model. After validating the numerical model using an analytical solution applied to a simpler reservoir/well model, complex reservoirs are simulated and pressure transient response signatures obtained. Sensitivities of key reservoir/well/fracture properties are investigated and a result of each case is presented. Finally, an actual case where seven transversal fractures of a long horizontal well is modeled using a sector of the full field reservoir simulation model (geological/structural), where the results are interpreted and discussed. Fracture characteristics have been approximately estimated by comparing real well test pressure buildup analysis from field and simulation results. Introduction The field studied is a carbonate formation in the Jurassic horizon in Saudi Arabia. It has been on development since 1945. Two predominant layers exist in this formation, C and D. The study herein is limited to the different zones comprising of layer D. Carbonate reservoirs are inherently heterogeneous in nature, in part due to the environments in which they are deposited and their subsequent diagenetic alteration. Layer D in this region is characterized by contrasts in rock properties. Variations in lithology, limestone and dolomite zones, porosity and permeability contrast of two orders of magnitude are common in this region. A typical formation D stratigraphic column consists of seven zones. Zone 1 at the top of the reservoir; contains the more developed porosity and permeability, is the most prolific and does not typically require stimulation. In contrast, zones 2 and 3 are classified as tight reservoir, thereby restricting hydrocarbon production when commingled at existing drawdown conditions with other more productive layers. Zones 4 and 5 exhibit better rock quality than 2 and 3, but they still benefit from stimulation. The bottom zones - 6 and 7 - similar to zone 2 and 3 in being tight, are best completed with selective fracture stimulation treatments. A well in this reservoir was selected to be acid stimulated using a multi-stage open hole completion system with isolation, mechanical diversion and selective fracture ports allowing the fractures to be placed at specific positions along the wellbore (Al-Naimi et al., 2008). Offset oil producers in the vicinity of this well demonstrate relatively high levels of total well production, but recent production logging results confirmed that contribution is dominated by dolomite section (zone 1). The result of this can lead to inefficient reservoir sweep and reduced or deferred recovery.

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