Hydraulic fracturing is being widely employed to augment wells’ productivity, thus facilitating proper depletion of the reservoir fluids and adding to the recoverable hydrocarbon reserves. The benefits of hydraulic fracturing are particularly pronounced in reservoirs exhibiting low permeability, high skin and, in case of gas condensate reservoirs, near wellbore condensate banking. A gas condensate field, code name ‘Delta’, has been producing from sandstone reservoirs for the last two decades. Most of the wells have been suffering from low productivity primarily due to a relatively low reservoir permeability (0.5 to 10mD) and high drilling induced skin. The problem has become more pronounced with the depletion of reservoir pressure resulting in condensate drop out around the wellbore. This paper details the envisioned economic incentives and the post-frac deliverability results from the recent hydraulic fracturing campaign carried out in a gas condensate field. The paper highlights the operational challenges encountered and the evolution of the hydraulic fracturing treatment design, execution and post-frac completion / flow-back strategy based on our experiences that contributed towards a successful and challenging campaign.

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Field A is one of the most challenging fields in the Potowar region of Northern Pakistan with severe problems of fluid loss, high-pressure shallow water influx, low drillability, clay reactivity/ shale instability and depleted reservoir sections. This paper gives a brief overview of the methods and changes made along with results achieved, enabling the well to reach total depth in just 31 days compared to an average of 150 days taken on offset wells. Due to severe drilling challenges, the wells were drilled in six-hole sections starting with 36" surface hole. An entirely new well engineering strategy has been utilized to enhance the drilling performance in the last five wells drilled in the field. Some of the major areas of change include Customized bit design, BHA and hydraulics design, casing design optimization and change in casing seat strategy as well as novel changes in drilling fluid design and selection of Loss Control Material. Dysfunctions and limiters in drilling which were affecting the hole cleaning, mechanical specific energy (MSE), hydraulics efficiency, and ROP were eliminated. A detailed analysis of the impact of changes in bits and bottom hole assembly design, drilling fluids design, and casing design is shared in the study for the last fifteen wells drilled in the field. Continuous learning and enhancements in all the subject areas are analyzed with respect to the use of different strategies and technologies. An analysis has been performed for non-productive time, its root cause and successful actions taken to reduce its occurrence. A huge reduction in drilling time, cost and risks have been achieved as a result of mentioned changes in the latest well setting a benchmark in the entire region. Dry hole time for the last well has been reduced by 78 %, while 65% cost reduction is achieved as compared to the previous average time and cost respectively. After removing the dysfunctions / limiters; ROP enhancement of 5 to 10 times has been achieved in different hole sections. The learning and experience from the use of discussed technologies and drilling practices can be helpful for optimizing challenging wells with the problems of pressure reversals, drilling fluids losses, well control, drillability issues in gumbo clay/ shales and wellbore stability.

Modeling fluid behavior using conventional nodal analysis software is a common practice in the oil and gas industry. However, understanding flow physics helps production engineers to understand the difference between predicted and actual flow behavior. This work presents a methodology applied to a depleting oil and gas field in northern Pakistan. The adopted approach not only helped to overcome vertical lift performance issues in the wellbore, but it also resulted in improved and sustained oil and gas production from the well. Based on these results, wells in the field with vertical lift performance issues were identified and evaluated using the analysis approach presented in this work. Basic petroleum engineering concepts are implemented using a multi-tier approach, and a proposal was outlined to understand the sluggish flow behavior from the well. The analysis approach characterizes the problem as "IPR dominated" or "VLP dominated" flow using the well's historical data and nodal analysis results, identifies the requirement for a new data set, and then operations are planned accordingly. During execution, coil tubing with memory gauges was deployed with a provision to simulate Coil Tubing Gas Lift (CTGL) with single point injection. This arrangement not only resulted in sustained production from the well, but it also provided leverage to gather bottomhole data corresponding to multiple flow parameters during sensitivity analysis. The workflow explains the physics behind oil and gas wells with sluggish liquid production and the inadequacy of conventional nodal analysis software in predicting production rates with certainty. The application of this workflow converted a "sick well" into a "sustained production well," which was previously ruled out for the implementation of ALS techniques during initial screening using conventional nodal analysis software. This novel approach highlighted the "domain of applicability" of conventional nodal analysis software and proposed a detailed workflow for artificial lift candidate selection. This workflow served as the blueprint for the overall evaluation of well productivity in depleting fields with VLP issues.

Casing degradation evaluation is of prime importance to ensure well integrity system reliability and sustainability. Multi-finger calipers have been around for more than 50 years and are used to assess internal casing damage. In addition, high resolution ultrasonic imaging, introduced relatively recently, determines casing thickness by transmitting pulse-echo waveforms to initiate thickness-mode of the casing through induction of mechanical resonance. A high-profile exploratory gas well was at stake of being compromised due to fishing and cable sticking incidents in the 7-inch section. In this work, a novel combination of multi-finger caliper and ultrasonic imaging is investigated to accurately determine metal loss with assistance of hybrid threedimensional casing morphological visualizations which is then utilized to validate casing derating models and ensure well integrity. In order to evaluate the casing condition, it was decided to run a 24-finger caliper tool and to make up for loss of coverage area, ultrasonic imaging was employed. In order to process caliper data from various fingers, a three-tier process was applied which includes finger calibration, caliper correction due to eccentricity, finger sticking, finger offset, and lastly statistical analysis was conducted to generate corrosion summary report for metal penetration computations. Next, characteristic of the casing resonance was processed to measure thickness and compared with the nominal thickness to determine metal loss percentage. Furthermore, arithmetical analysis of internal casing radius measurements from both the tools was done to ensure data reliability. Ultimately, combining the measurements, 3D descriptions were generated in order to better characterize localized damage. A multi-physics approach led to a comprehensive characterization of in-situ casing condition. Consistency between internal radius measured by the calipers and deduced by pulse- echo arrivals was observed, improving confidence on the end-product. In the 7-inch casing section, a 40-meters interval was identified to have medium intensity grooves where the maximum penetration was computed to be in excess of 20% of the nominal pipe thickness This groove can be associated with tripping in / out operations of drill string or BHA. Also, the log results agree with the relatively higher side forces across this interval due to increased dog-leg-severity. In addition, cyclic response in radius measurements identified another zone where potential casing deformation (ovalization) near the surface was observed. Results of torque and drag simulations and well trajectory parameters were integrated with casing degradation analysis from the logs which assisted in qualifying well barrier status for the casing.