The channel fracturing technique achieves heterogeneous proppant placement by pumping pulses of proppant laden slurry and clean fluid in alternating sequence. Successful creation of proppant banks in the fracture provides stable channels of infinite conductivity which reduces pressure drop across the hydraulic fracture and enhances production. To date, more than 15,000 fracturing jobs have been successfully placed in various types of formation and completions using the heterogeneous proppant placement technique. The mechanics of delivering the treatment involves pumping pulses of alternating clean and dirty pulses of fluid with fibers that keeps the proppant in suspension. This is then followed by a continuous proppant "tail-in" stage towards the end of the job before the flush stage. This tail-in ensures continuous proppant bank at the near wellbore region to ascertain good connectivity between wellbore and the channel spaces created during the treatment. To understand importance and requirement of tail-in, simulations and field execution of jobs with or without tail-in in channel fracturing treatment have been done. Furthermore, a bigger sized unconventional rod-shaped proppants have been also used towards end of the channel fracturing treatments. The unconventional proppants not only helped on such treatments to minimize pressure drop across the tail-in but also helped to reduce proppant flowback in softer formations. The impact of tail-in on pressure drop and production rates in different formations have been consolidated in this study which provides proppant selection criteria for channel fracturing tail-in stage. Simulation results in shale and sandstone reservoirs and the field treatment case histories comparing the production results for wells completed with and without tail-in in channel fracturing treatment are presented.

The deep high pressure/high temperature (HPHT) dolomite formation in Northern Kuwait has been a challenge with varied production, attributable to reservoir heterogeneity. Due to the tight nature of these rocks, matrix acidizing may not produce desired effects, thus requiring hydraulic fracturing to produce at economic rates. However, the tectonic setting in high stress environment has resulted in subpar success and inconsistent results from stimulation treatments in matrix and hydraulic fracturing applications. This paper presents a multidisciplinary approach to address the limited success in the Northern Kuwait Dolomites. An integrated petrophysical evaluation of the current wells will be followed with multi-well Heterogeneous Rock Analysis (HRA), to evaluate the reservoir heterogeneity across the field and identify the ‘sweet spots’ for future drilling locations. Evaluation and lessons learnt from the past stimulation treatments, will be used to understand geo-mechanical challenges and to help calibrate the Mechanical Earth Model (MEM) for implementation in the future wells. Finally, using a reservoir-centric stimulation design tool, stimulation type (acid fracturing vs proppant fracturing) and stimulation design optimization for future wells will be developed. A reservoir-level petrophysical evaluation of the existing wells was performed and compared to understand the reservoir heterogeneity vis. a vis. production potential. Multiple rock classes were identified within the tight dolomite interval, with a gross thickness of ~250 ft. Starting with log based MEM, results from the image log interpretation and the field observations/measurements from fracture diagnostic tests (Decline analysis, Calibration injection) were used in calibrating the MEM and mapping the Completion Quality (CQ) heterogeneity across the field. This has led to a reservoir-level understanding, which can enable planning optimal well locations, target interval and subsequent well placement/completions methodology. Finally, using the reservoir-centric design tool, an optimum design to effectively stimulate the ultralow-permeability dolomites was determined. The optimization workflow did not only include a single-faceted approach of fracture modeling, but also encompassed a production forecast using the integrated numerical reservoir simulator. Lessons learnt from the optimization workflow were further extended to designing horizontal wells (landing point, trajectory for optimal stimulation geometry), and hence to aid in field development strategy. Using the multidisciplinary unconventional workflow, the heterogeneity in reservoir quality and completion quality was evaluated, both along the wellbore and spatially. In essence, we found that natural fractures along with high Critical Net Pay (CNP) allows you to vertically connect with good RQ and thus, is required for success in these tight reservoirs. Following which, reservoir-centric stimulation design tool enabled optimization of completion and stimulation design in a holistic approach, to maximize appraisal and production opportunities.

Appraisal program of the deep gas/light oil from unconventional reservoirs in North Kuwait is strategically important to secure the challenging hydrocarbon production targets of Kuwait Oil Company (KOC). A very deep high-temperature/high pressure (HT/HP) dolomitic formation is at approximately 15, 000 ft (vertical), poses complex completion and producibility challenges. Exhaustive log suite and core analyses confirm some porosity development and gas shows. Unlike the proven carbonates up-hole in the same asset, the deepest dolomite units have extremely low permeability, and may not flow unless enhanced by a natural fissure network and/or hydraulic fracturing. Only a few wells have been attempted for completion in these deepest dolomite layers, which failed to flow even after matrix acidizing treatments. The effective completion design will require good understanding of formation mechanical properties and fluid leakoff behavior, leading to optimal horizontal wells to maximize reservoir exposure completed with multiple hydraulic fracturing treatments to establish hydrocarbon production at commercially acceptable rates. Therefore, properly designed and effectively executed extensive fracture diagnostic tests are critical in the current pre-appraisal stage. In addition, multiple acid-fracturing treatments have already contributed to the understanding of fracture geometry development and fracture flowback characteristics. A fracture diagnostics workflow was developed and deployed to appraise the deepest dolomite layers. Critical fracture mechanics data were collected and analyzed. The main fracturing treatments have also yielded crucial results, which will help the design team in optimizing the horizontal well completions. This comprehensive workflow can be successfully applied in characterizing challenging formations elsewhere where the well and regional data are limited in the appraisal of similar light oil/tight gas-bearing unconventional carbonates.

Cambay is one of the oldest basins in India producing hydrocarbons since 1960's. It stretches almost 400 kilometers from south of Rajasthan to south of Gujarat in the western part of India and covering 53,000 sq. Km of total area. Cambay basin is contributing almost one-third of India's total onshore oil production. Raising production from Cambay basin is a considerable challenge as major producing fields are all Brownfield's. Hydraulic Fracturing (HF) is in use since 1980's to stimulate and enhance production from average to poor quality sands of Cambay basin. HF leads to better production results and has helped in enhancing production from this region for a long time. HF success ratio in stimulating these reservoirs dwindled significantly in the last decade due to continuous exploitation and decrease in saturation and reservoir pressures in the area. Enhancing fracture effectiveness & conductivity and reducing pressure drop within fracture was key to overcome this challenge and take the production to the next level. Maximizing conductivity of proppant pack has its own inherent limitations and this led to the application of channel fracturing for the first time in India in the Cambay basin. Channel fracturing results in decoupling fracture conductivity from proppant pack conductivity and results in infinite fracture conductivity, longer effective fracture half-lengths & reduction in pressure drop in the fracture. Creating stable fracture channels is highly dependent on rock mechanical properties and first hand evaluation of this decides applicability of this technology in a particular field/sand. This paper discusses the production results of wells treated with open channel fracturing compared to production results of offset wells stimulated by Conventional fracturing technology. Then it sheds light on basic requirement and key factors to be able to decide applicability of this technology in a particular field/sand. In the end applicability of this novel technology in all the major fields of Cambay basin will be discussed with the overall scope of redevelopment of all the major brown-fields of India.

Candidate recognition in mature brown fields and depleted fields for stimulation has always been a challenging task. It has become a common practice for many operators that when all else fails they turn to stimulating the well. The application of fracturing for any poor producer in a brown field does not guarantee success. Since traditional reservoir engineering methods like skin analysis via build-ups cannot be applied in these depleted reservoirs alternative techniques have to be used.Identifying and stimulating key wells requires a systematic candidate recognition process with emphasis on the ability of the well to deliver post stimulation. Having a method to score completion and production integrity based on its petrophysical and geomechanical characteristics and thoroughly understanding the operating environment ensures a much better chance for these wells to be successful. Comprehensive candidate selection methodology with available data was devised to identify best stimulation candidates from existing set of wells. Comparative Petro-physical log evaluation, Mechanical Earth modelling and oriented perforations in selected wells was deployed to further understand reservoir and rock mechanical properties and limit surface pressures by minimizing near wellbore perforation and tortuosity effects.Further to estimate economic viability; analytical modelling and Arps production decline was combined utilizing local learnings and experience to predict post fracture production. Full set of diagnostic tests was done to make a robust model that can simulate fracture propagation and help in optimizing fracturing design to place desired fracture in place. Post fracturing cleanup and well activation was closely monitored with design and recommendation on required Artificial Lift techniques as and when required. Production results achieved after applying this workflow exceeded initial expectations set by operator. Payout period achieved for total investment in this project was 75-150 days. Due to these encouraging results, same workflow was applied in number of depleted fields in Cambay basin with similar results. This paper will summarize the workflow used for revitalizing production from some of the major fields including Candidate selection methodology, Petro-physical evaluation, Mechanical earth modelling, diagnostic tests for fracturing design, production forecasting, post fracture well activation and artificial lift design. In the end, possibilities of deploying this workflow for re-vitalizing other brownfields will be discussed.