To overcome the challenges specific to unconventional reservoirs that are being targeted across the Middle East region a synergy of unconventional technologies is needed. Fracturing fluids are one of the critical components of multi stage proppant fracturing solution when targeting extreme HPHT reservoirs while aiming to preserve freshwater. The objective of this paper is to reveal the performance of unique fracturing fluids that have been recently tailored and applied to tackle tight and unconventional reservoir challenges. Three very different unconventional: polymer-free, carboxymethyl hydroxypropyl guar (CMHPG) and poly-acrylamide based fracturing fluids are presented in this work. They have been field-tested and recently successfully applied in the tight and unconventional reservoirs of UAE as well as the Middle East and Asia. These fracturing fluids collectively address the full spectrum of existing and future reservoir target bottom-hole temperatures ranging from 50 degF up to 450 degF. The unique chemistry characteristics for each of the fluids will be elaborated together with laboratory test results that will include compatibility, rheology and other qualification tests. Furthermore, results of extensive qualification tests performed to address specific local challenges will also be presented. All three fracturing fluids were effectively applied leading to treatment success and proving their performance in extreme reservoir temperature, stress or operational environment that demands high-efficiency. Each fluid proved compatibility with used mixing water and reservoir fluids tested. These fracturing fluid types can be continuously mixed simplifying operation, reducing fracturing equipment layout and minimizing waste. All these improvements are critical in an offshore operating environment. Polymer-free and CMHPG based high viscosity fluids are formulated with sea water to minimize environmental impact. Furthermore, these fluids are continuously mixed with seawater addressing the conventional fracturing fluid logistic constraints offshore. These key improvements made massive offshore and multi-stage proppant fracturing treatments technically and economically feasible. The novel unconventional fracturing fluids elaborated in this paper offer a set of unique technical capabilities that did not exist previously. These three fluids are critical technology enablers and they are part of a multi-disciplinary, integrated technical collaboration project aiming to efficiently and effectively address local complex subsurface conditions and stringent economic requirements of remote offshore operations.

In recent years, a major Abu Dhabi offshore operating company has shifted towards utilizing Maximum Reservoir Contact (MRC) wells to improve oil production and long-term oil recovery. The initial MRC pilots demonstrated the importance of designing the well and completion to facilitate intervention and stimulation. Coiled tubing stimulation methods applied in these first wells were able to meet the objective by significantly improving overall oil production and water injection. However, as we move into tighter formations and longer wells the efficacy of coiled tubing is significantly reduced by limited accessibility and restrictions on the rate. The MRC strategy is being implemented in Reservoir II which is the largest reservoir in terms of Oil in-place. Reservoir II is a thick multilayered limestone reservoir characterized by its low permeability. This low permeability becomes more pronounced as one moves from the crest of the field to the periphery of the field. In such tight reservoirs (Reservoir II), conventional techniques may yield lower than expected production results. In an effort to improve production and ultimate recovery, a new stimulation and completion strategy is required that improves contact with the reservoir beyond the wellbore. In this paper we will discuss the design and implementation of a new technique intended to improve the production and recovery from tight reservoirs. This technique combines a fit-for-purpose limited entry type completion with high rate acid stimulation. Pre- and post-production comparisons demonstrate a substantial production increase and uniform contribution along the extended horizontal interval. We will review the design approach, job execution and evaluation of pre- and post-production performance. We highlight key technical challenges and risks encountered during the preparation, design, execution and evaluation stages of this operation and discuss how these were overcome and mitigated for the improvement and optimization of future MRC wells.

Increasing natural gas demand in Indonesia has driven many operators to develop potential gas field assets, whether offshore or onshore, across Indonesia. One such field is BC which is located offshore East Java in a tectonically active area and part of the ABC complex. The field is composed of carbonate rock which is globigerinid in nature, with the presence of different facies such as packstone, wackstone and grainstone, of which the latter has the best permeability. An extensive geomechanical study was conducted and one of the conclusions was that solids and fines production to some degree are likely to happen from the carbonates in this field. To minimize the risk of solids production, an openhole gravel pack (OHGP) system was designed and deployed. Horizontal OHGP involving screens equipped with shunt tubes for alternate packing are commonly deployed in unconsolidated sandstone formations around the world. The use of filter cake breakers, during or after OHGP placement, is regularly included as part of these treatments. The BC is a carbonate field, besides the low frac gradient and the naturally fissured characteristics associated to the rock which makes it prone to high leak-off, the completion strategy required a special designed filter cake breaker inert to the formation and capable of helping to minimize the lift-off pressure; the challenge required a different approach. The successful completion of these wells required the use of state-of-the art gravel pack placement simulator, special analysis of Bottom Hole data during gravel pack placement and customized gravel pack fluid, capable of transporting proppant and clean the filter cake afterwards. One deviated and three horizontal wells with 9 5/8-inch casing and average of 8.6-inch openhole diameter were drilled and successfully completed. Gravel pack placement interpretation using bottomhole gauge data indicates full annular packing for all OHGP cases. After completion, wells were started smoothly with no solids production observed. This paper highlights key technical challenges and risks encountered during the preparation, design, execution, and evaluation stages of this operation and discusses how these challenges were overcome and the risks mitigated. Finally, the lessons learned and their implementation towards the improvement and optimization of future operations are discussed.

Hydraulic fracturing is an important technique widely used for to improve well productivity in tight reservoirs and enable economic development. Geomechanical modeling is an important prerequisite required to ensure effective fracture construction and the required contact with the formation. In this paper, we show the first successful hydraulic fracturing in the Offshore Abu Dhabi clastic sand formations in which geomechanical modeling played an essential role in fracture design, completion design and successful execution.The geomechanical properties and behavior of the clastic sand formations are still largely unknown in the Abu Dhabi region. In other parts of the Arabian Plate this formation is known to be a complex geological environment with high fracture gradients, poorly consolidated intervals, natural fractures and often rock that exhibits poroelastic behavior.Due to the aforementioned complex geological environment resulting geomechanical attributes, the fracture design and key inputs including the calibrated Mechanical Earth Model (MEM) were essential to the successful design and execution of the first hydraulic fracturing in the Offshore Abu Dhabi clastic sand formations. The lessons learned during this successful design and application is critical for the design of future wells and the development of the UAE clastic sand formations.The constructed MEM played a key role in successful hydraulic fracturing. Fracture height, length, width, direction, complexity and overall fracture performance are all largely controlled by the formation stresses, stress direction, rock properties and complexity of the rock fabric.Geomechanical properties in the clastic sand formations in Abu Dhabi offshore were evaluated with less uncertainty by utilizing the advanced MEM. The calibrated MEM was integrated with an advanced fracture design simulator to optimize hydraulic fracture design. Results of the advanced MEM agreed well with fracture diagnostics and temperature surveys.Work flow in this geomechanical analysis can be applied to hydraulic fracturing in other offshore tight reservoirs with a complex geological environment. Understanding the geomechanical properties of a formation allows engineers to optimize well placement, completion design, perforation placement, charge/gun selection and fracture design for improved well productivity.

Exploration of the Palaezoic tight gas sands has been ongoing in Abu Dhabi since the early 1980s. The first discovery of gas in this formation dates back to this period; however commercial rates were not proven due to mechanical issues and the overall tight nature of the Pre-Khuff clastics. This formation is not only of interest as a source of gas, but also because gas shows and production from this formation have shown to be free of hydrogen sulphide.Many wells in the Abu Dhabi Pre-Khuff have resulted in good gas shows while drilling, but did not produce. The poor production test results are not surprising if we consider formation damage the low permeability of the reservoir as regional experience has shown that commercial production rates are only achievable through the application of hydraulic fracturing.Hydraulic fracturing in the Abu Dhabi Pre-Khuff formation is not without its challenges. The depth of this target creates a high pressure and high temperature environment which requires special equipment and technologies. The geomechanical properties and behavior of this formation are largely unknown in the Abu Dhabi region. In other parts of the Arabian Plate, this formation is known to be a complex geological environment with high fracture gradients, the poor consolidation and a high risk of poroelasticity. The aforementioned attributes make the Pre-Khuff formation a challenge to successfully fracture stimulate.In a recent Pre-Khuff exploration well, hydraulic fracture stimulation was successfully implemented as part of the completion strategy. This new technique resulted in the successful production test of a Pre-Khuff target at commercial gas rates. In this paper we will show how the integration of petrophysical data, core data, geomechanical interpretations, lab/fluid testing and fracture diagnostics were used to design and optimize the hydraulic fracturing treatment. We highlight key technical risks and challenges encountered during the preparation, design, execution and evaluation phases of this operation and demonstrate how these risks were mitigated and the challenges overcome.. Finally, we will discuss how these methods and workflows can be applied for the improvement and optimization of future Pre-Khuff wells.