Raageshwari Deep Gas field is a relatively deep (2800-3500 meters) unconventional volcanic reservoir with pressure and temperature of ~ 5200 psi and ~ 140 degC respectively. Wells were completed as 3-1/2" Monobore producers and plug & perf method was used for fracturing stimulation. 3-1/2" 10000psi rated millable bridge plug was installed immediately after the fracturing stimulation which were then milled by coiled tubing based milling tools to clean up & test all the zones commingled. During milling of bridge plugs, substantial amount of gas along with significant condensate was produced from the zones, which resulted in vast variance in Coiled tubing circulating pressures and well head pressures. As a consequence, WOB was increased, in an effort to speed up the milling process. Unfortunately this resulted in frequent motor stalling and inefficient milling. Also, managing large amount of produced gas and condensate, along with milled cuttings, sand, gel and water, was an issue with regards to conventional surface equipment’s and frenzied flaring of condensate in vicinity of other gas producing wells. This paper describes how the bridge plug milling process was optimized over the course of the campaign of hydraulically fractured gas wells. This optimization included all aspects of the milling operation such as, WOB, penetration rate, milling fluid system which facilitated the increase in frac fluid recovery, as well as the differential pressure across the motor. This optimization reduced the bridge plug milling time to between 30 and 45 minutes. It also summarizes the challenges which had to be overcome during the successful implementation of this technique and the lessons learnt in due course of time. This paper also describes the use of a sand catcher along with the conventional surface well testing unit and an inventive surface rig up which not only assisted in perfectly managing the milling cutting, sand, gel and water at surface, while completely eliminating the requirement of flaring the condensate. The technique helped save about 5% of the total well cost well by reducing the number of days required for milling operations and the associated daily rental of surface well test and Coiled tubing spreads. This technique also ensured minimum flaring of hydrocarbons and faster hookup of wells to production facilities and therefore is strongly recommended in high condensate gas wells located in environmentally sensitive locations with HSE and economic concerns.

Hydraulic fracturing stimulation is considered a successful development technique in tight gas reservoirs. However, these expensive operations sometime underperform due to ineffective fracture fluid (FF) clean-up. This paper concentrates on FF clean-up efficiency for a Multiple Fractured Horizontal Well (MFHW) completed in both homogeneous and naturally fractured (NF) tight gas reservoirs. The emphasis is on NF reservoirs that make up a large percentage of tight gas assets, as their clean-up efficiency has received little attention. In this study, two numerical simulation models, i.e. a single-porosity single-permeability and a dual porosity-dual permeability model representing a homogeneous and a NF tight gas reservoir respectively, were used. Simulations were conducted on a MFHW with seven hydraulic fractures (HF). The process comprised of injection of FF, then a soaking time (ST) followed by production. The impact of various parameters which includes ST, FF viscosity, pressure drawdown and parameters pertinent to relative permeability and capillary pressure in matrix, hydraulic and natural fractures, were evaluated. In addition, based on a newly proposed treatment process that generates in-situ pressure and thermal energy that breaks gel viscosity, the effect of resultant viscosity reduction and local pressure increase, for improving the clean-up efficiency was also assessed. In these simulations, and due to uncertainty in its value, NF permeability was varied over a wide range. For conclusive purposes, Gas Production Loss i.e. GPL (%) defined as the difference in total gas production between the completely clean and un-clean cases as a percentage of the clean case, after a specific production period was used. This paper prioritizes the impact of pertinent parameters and highlights the influence of thermochemicals on the clean-up efficiency thereby justifying its commercial practicality. For instance, it is shown that the presence of NFs results initially in higher GPL but then GPL reduces significantly. Reducing the FF viscosity improves clean-up significantly especially for the NF models as NFs are the main contributor to the gas and FF flow from the reservoir to surface via hydraulic fractures. The sometimes non- monotonic trend of GPL variations, depends on the specific combination of NFs’ permeability and FF viscosity which results in the certain fluid invasion profile and mobility in the system. The paper emphasis is on the impact of thermochemicals and natural fractures on the cleanup up efficiency of hydraulic fracturing stimulations that should be optimized to reduce cost, thereby increasing the profit from these projects.

Aishwariya Barmer Hill (ABH) field is a moderate permeability (0.5 – 4 mD) oil bearing porcellanite with alternating sequences of tight shale. After successful appraisal campaign a full field development with multi-stage fracturing using cemented frac sleeves, field was brought online with Hydraulic Sucker Rod Pump (HSRP) as artificial lift and has been on production since 2019. However, a need was felt to review the frac and completion design on account of challenges faced during fraccing and unplanned downtime during production operations. Critical observations that prompted a change in completion and frac technology are: Formation rock pebbles and proppant were observed in the wellbore during workovers.Reservoir's low Young's Modulus (YM) allows the generating high strains at low pressures, while low Poisons Ratio (PR) makes the rock brittle and shatter under high deformation. Consequently, shattered rock was not able to hold the proppant in place after fracture closure resulting into flowback of proppant and pebbles.Debris fill in wellbore resulted in production impairment and malfunctioning of HSRP. To mitigate the identified risks, the design change incorporates measures to address post fracturing production problems related to high treating pressures as well as optimize number of frac stages and stage spacing. Uniform proppant distribution with lesser number of stages is targeted by utilizing limited entry technique to help in distributing treatment pressures and proppant in multiple clusters as well as limit net pressure build up in each frac. It will help prevent rock shattering and better retention of proppant after frac closure. Completion design workflow includes log based zonal isolation between each stage and frac design for two to three cluster per stage. The revised design will predict the number of stages in each well for optimal utilization of wellbore for best economical production. Revised frac design has been implemented in 5 infill wells wherein 66 stages have been pumped without TSO signature or premature screen out in any of the stages. Wells have been put on production and are performing better than rest of the wells in the field. There has been no evidence of debris accumulation in wellbore or proppant flowback in production fluid. Further drilling campaign for 15 wells has been planned with cluster frac strategy with revised frac design.

Raageshwari Deep Gas field is located in RJ/ON 90/1 Block in western India is a retrograde gas condensate unconventional volcanic reservoir. It consists of streaks of low permeability sand which require hydraulic fracturing to achieve commercial production. Plug and perf stage technology along with limited entry was used to ensure that most of the productive pay was stimulated. Production data, Frac and Reservoir parameter were evaluated vis-à-vis Productivity Index (PI) and interdependencies were understood. Multiple stages in a particular well were stimulated by hydraulic fracturing with each stage having from 1 to 6 perforation clusters to ensure maximum kH coverage. Different treatment designs varying in job size, proppant type, concentration and pumping rates were prepared and executed based on the formation type, net pay and petrophysical properties. After flowback and initial cleanup, the wells were hooked to the production facility. Memory production logging was then conducted in a time phased manner and the interpreted data was used to determine the PI evolution of individual cluster of all the 93 stages in 15 wells. Time lapse PI of individual clusters as well as specific stages were plotted against: Proppant pumped per net payAverage permeabilityEffective porosityTotal proppant pumpedElevation depths of the Fatehgarh, Basalt and Felsic formations of the reservoir stretching from north to south of the field. Important observations resulted from this exercise such as: The top most basalt stages are attributing a large portion of the 15 wells total cumulative production. It outperformed the shallower Fatehgarh sands which were thought to be more prolific.Well PI clearly supports the changes expected in the reservoir quality from north to south of the field and is in line with the OH logs.PI of wells in a particular area shows gradual improvement in contrast to the other wells PI.Positive effects of flowing back an inferior quality pay before fracturing the upper superior quality pay. This study will not only assist in determining the optimum proppant pumped per net pay height for different formations but also facilitate in eliminating frac stages in a well which would result in significant cost reduction in upcoming development campaign of 42 wells. This holistic workflow will be used for refining the number of frac stages in a well as well as determining an ideal proppant quantity for a particular stage in volcanic pays. Detailed analysis of production data supported in identifying the key frac and reservoir parameters which subsequently will aid in improving hydraulic fracturing efficiency. Representative case histories of production results assisted in finalizing well services activities to improve the overall well PI.

Objectives/Scope Raageshwari Deep Gas field located in southern Barmer Basin, in the state of Rajasthan (India), consists of a laminated reservoir where conventional fracturing treatments with a single set of perforations are not economical. In order to improve the project economics, limited entry treatment design (Lagrone, 1963) selected for fracturing. The effectiveness of fluid diversion during limited entry fracture treatment in a laminated reservoir was validated using post injection temperature surveys. Methods, Procedures, Process The Limited entry design relies on the pressure drop across the perforations to balance the flow between the various perforation clusters. The treatment design was based on achieving a minimum of 700 psi of perforation friction for adequate diversion between the zones. The perforation friction and number of active perforations was determined using Step Rate/Step Down Tests (SRT/SDT). Post injection temperature surveys were used to confirm fluid entry into the various perforation clusters. Results, Observations, Conclusions The following process was applied to more than 90 fracture stages in 15 wells. The fracturing treatments were modeled using log derived mechanical properties and stress contrasts. Diversion into all the clusters was insured by distributing the available perforations based on the predicted fracturing pressure for each zone. Post injection temperature surveys were used to validate the fracturing models. While somewhat qualitative, the post injection surveys did provide valuable insite in some cases, the fracturing simulator predicted fracture growth out of the desired stage area. The post injection temperature survey helped to validate predictions of: In some cases, post SRT temperature surveys helped justify decisions addition of holes to minimize perforation friction or addition of extra cluster(s) to maximize pay coverage. Novel/Additive Information While the use of temperature surveys to estimate fracture height is not new, we believe that this is the most extensive use of temperature surveys in a medium size project incorporating limited entry.