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Collaborating Authors
SPE/PAPG Annual Technical Conference
An Integrated Approach to Evaluate Naturally Fractured Carbonate Reservoir in TAL Block, Kohat Basin
llyas, Asad (MOL Pakistan Oil & Gas Co. B.V Islamabad-Pakistan) | Farooq, Umar (MOL Pakistan Oil & Gas Co. B.V Islamabad-Pakistan) | Ahmad, Jawad (MOL Pakistan Oil & Gas Co. B.V Islamabad-Pakistan) | Saleem, Omer (MOL Pakistan Oil & Gas Co. B.V Islamabad-Pakistan) | Palekar, Arshad Hussain (Schlumberger, Islamabad-Pakistan) | Ramzan, Muhammad (Schlumberger, Islamabad-Pakistan) | Siddiqui, Faraz Hassan (Schlumberger, Islamabad-Pakistan)
ABSTRACT Petroleum play in North Pakistan comprises of naturally fractured reservoirs (NFR) both in clastics and carbonates. These fractures play key role in the determination of reservoir quality and production behavior of the formations and is a subject of interest for E & P companies particularly working in Kohat Plateau. In TAL Block, naturally fractured Lockhart formation has very low matrix porosity and fractures provide the main source for storage and fluid flow in it. It has also been observed that all the fracture sets in carbonate reservoirs do not contribute to flow. Flow variations have been observed with different fracture trends identified from open-hole logs based on their connectivity, fracture apertures and secondary porosity. This leads to the development of an integrated approach using existing information from open hole logs, image logs, formation tester and production logs to optimize the reservoir modeling, history matching and selection of future perforation intervals. In this paper, data from six wells located in different structures in TAL Block has been utilized to study the behavior of naturally fractured carbonate reservoir. During the study, it was observed that in some wells, the top part of Lockhart formation was contributing more to production while in others, the bottom part was more productive. These flow variations could be associated with different fracture trends, their connectivity, fracture apertures and secondary porosity. This problem was addressed by sub-dividing Lockhart in to different layers/facies based on fracture evaluation (types, density, secondary porosity, nodularity and rock texture), open hole logs, formation tester results and production logs interpretation.
- Geology > Geological Subdiscipline > Geomechanics (0.70)
- Geology > Rock Type > Sedimentary Rock (0.69)
- Geology > Petroleum Play Type > Unconventional Play > Fractured Carbonate Reservoir Play (0.60)
- Asia > Pakistan > Khyber Pakhtunkhwa > Upper Indus Basin > Potwar Basin > Tal Block (0.99)
- Asia > Pakistan > Khyber Pakhtunkhwa > Kohat Basin > Kawagarh Formation (0.99)
- Asia > Pakistan > Khyber Pakhtunkhwa > Karak District > Lockhart Formation (0.99)
- (2 more...)
Abstract The prime objective of presenting this paper is to disseminate experience so as to optimize treatments to increase hydrocarbon production and to protect downhole assets from producing oil and gas wells. The authors want to share their pertinent experience for application to increase production, reduce corrosion and scale formation down hole with effectiveness and pecuniary advantages to the Operators. "Knowing Your Wells". This is an important criterion. With the correct knowledge, targeting the correct type of wells and when to charge the well with foam sticks can increase production by as much as 25-30%. Secondly, the encapsulated inhibitors application are an inexpensive choice for bottom hole treatment applications against scale and corrosion. The application of Gas and Foam sticks and encapsulated inhibitors are a low cost method compared with Oil field standard techniques. The well selection criteria depend on well completions, bottom-hole configuration, well integrity, flowing parameters and fluid constituents. Oil and Gas wells can be internally protected and therefore sustaining production with less intervention, resulting in considerable reduction in maintenance costs using these methods. Also both these techniques can be used in conjunction with other procedures, for example, after coil tubing jobs, immediately charge the well with the appropriate encapsulated inhibitor. In the case of Foam sticks as pressures drop and flow decreases, using the foam stick technique can keep the well flowing at the higher production rates. Both these techniques are not a solution to every problem well but when used in the correct manner on suitable wells with the correct treatment, increase in production is achieved with a considerable reduction in CapEx & OpEx.
- Asia > Pakistan (0.29)
- North America > United States > Louisiana (0.24)
- Asia > Middle East > Qatar > Arabian Gulf > Rub' al Khali Basin > North Field > Laffan Formation (0.99)
- Asia > Pakistan > Punjab > Upper Indus Basin > Potwar Basin > Dakhni Field > Chorgali-Sakesar Formation (0.98)
- Production and Well Operations > Well Intervention (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Inhibition and remediation of hydrates, scale, paraffin / wax and asphaltene (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- (2 more...)
Remedy of Severe Scale Build Up Issue in OMV (Pakistan) at Well 'X'
Hassan, Syed Saadat (OMV (Pakistan) GmbH) | Ahmad, Tofeeq (OMV (Pakistan) Exploration GmbH) | Farooqui, Shoaib (Weatherford Oil Tools ME Limited Pakistan) | Ali, Haseeb Mazhar (Weatherford Oil Tools ME Limited Pakistan) | Qamar, Atif (Weatherford Oil Tools ME Limited Pakistan)
ABSTRACT With current demand for gas at historic peak, any decrease in production due to deposits of scale within tubing is the most troublesome for any E&P company. Statistically 28% of time it is the scale in well that hinders producing it at optimum rate. "Carbonate" and "Sulfate" scales are most common of mineral scales that form in wells. Carbonate scales are generally tackled by wellbore cleanout with acid or by using scale inhibitors to slowdown scale deposition process but none of these solutions solve the problem on permanent basis. Sulfates scales are generally very hard to remove through acid job and usually chemical chelants are used to control sulfate scales. The major production enhancement challenge faced in well ‘X’ was to permanently mitigate severe scale build up issue in tubing for optimum production performance. This paper presents how these challenges were faced and overcome by using ClearWELL* unit, resulting in stable and continuous production. A scale study was conducted by OMV laboratory in Vienna to identify the scale build up mechanism and solutions for its mitigation. The study confirmed that minor pressure decrease at formation temperature promoted water transfer into the gas phase, if water rate is low compared to gas rate, this can result in complete evaporation and formation of precipitate leading to scale build up (mainly calcite). To reinstate production, repeated wellbore cleanouts with coiled tubing using diluted HCl (7.50%) were thought to be the temporary solution in fighting CaCO3 scales. ClearWELL unit was commissioned at well ‘X’ x-mas tree, which is currently under pilot testing. It is an electromagnetic device which continuously generates electronic dipole that induces a randomly varying high frequency electric field throughout the entire piping system. The electric field generated by device forces homogeneous crystal formation in suspension rather than on metal surfaces. Scale crystallizes in suspension and is carried away with gas water mixture. During last 5 months of its pilot testing, results achieved so far are promising. Stable and no lost production added a reasonable value to the producing asset and saved huge revenue loss to the company.
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Constituents > Salts/Sulphates/Scales (0.35)
- Well Completion > Completion Installation and Operations (1.00)
- Production and Well Operations > Well Intervention (1.00)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Inhibition and remediation of hydrates, scale, paraffin / wax and asphaltene (1.00)
Fracturing Treatment/Geometry Optimization and Post-frac Performance Evaluation in a Tight Gas Reservoir
Khan, Osama Hasan (NED University of Engineering & Technology) | Ali Virk, Muhammad Muneeb (Pakistan Petroleum Limited) | Ahmed, Sheraz (NED University of Engineering & Technology) | Sajid, Muhammad Ali (NED University of Engineering & Technology) | Abrar, Saad Bin (NED University of Engineering & Technology) | Lakhani, M. Haris (NED University of Engineering & Technology)
Abstract Unconventional gas resources, tight gas in particular, complements other major sources of hydrocarbon which if exploited effectively can play a significant role in meeting today’s energy challenges faced by Pakistan. The production of these major resources poses many economical challenges, which could be overcome by the astute use of available resources and technological efficacy. Hydraulic fracturing is an essential stimulation technique for the economic development of tight gas reservoirs. Mostly, fracture jobs are designed based on the maximum achievable treatment sizes which can result in wider fracture width, greater height, and longer half length. The ultimate aim is to achieve maximum deliverability. This approach is not versatile because the treatment parameters and fracture geometries are not sensitized. As a result, the treatment sizes and geometries are not the optimized ones. A better approach is to determine the best compromise between the resources available and the productivity enhancement achieved i.e., optimizing the fracturing treatment and geometry both physically and economically. Once the optimum balance is found, the next step is to establish the operational parameters (e.g. Pump Rate, Net Pressure, etc.). This paper discusses the process to achieve the optimum fracturing treatment and geometry design and compares the actual field results obtained with those predicted. The analytical Pseudo-3D model has been used for the simulation of fracture propagation and optimization of parameters. The post-frac performance of the reservoir is predicted using both analytical and numerical methods (Using numerical reservoir simulator). In order to validate the analytical and numerical models, the actual fracturing results from the field (fracture dimensions and deliverability) have been compared with those predicted by the model. The same fracturing treatment parameters that were used in the actual job execution have been used in the model validation process. Once the model is validated, the difference between the optimized treatment parameters and that used in the actual executed job has been highlighted; these differences emphasize the value of using the optimization process defined in this paper to achieve the best possible deliverability in an economically efficient manner. The paper presents a systematic approach towards the optimization process of the fracturing treatment and geometry for tight gas reservoirs, which in turn influence the post fracturing deliverability results. The sensitivity analysis points out the parameters to which the fracture deliverability is most sensitive. The determination of such parameters and hence the fracture geometries remains a big challenge for tight gas reservoirs and industry remains committed to developing a thorough understanding of tight sands behavior.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.32)
First Horizontal Well Drilled with Underbalance (Nitrified Stable Foam), Downhole Deployment Valve & Extended Range EM-MWD Technologies in Middle East Region - Case Study and Lesson Learned
Hussain, Sajjad (Pakistan Petroleum Ltd.) | Saleem, Saad (Pakistan Petroleum Ltd.) | Sabir, Shahid Majeed (Weatherford Oil Tools M.E. Limited, Pakistan) | Asrar, Muhammad (Weatherford Oil Tools M.E. Limited, Pakistan)
Abstract The name "Sui" has become synonymous with natural gas in Pakistan. Located at a distance of about 650 kilometers (km) from Karachi in Balochistan Province, Sui is Pakistan Petroleum Limited’s (PPL) flagship gas field. The gas field was discovered in the late 1952 and the commercial exploitation of the field began in 1955. Two major reservoirs of this field are Sui Main Limestone (SML) & Sui Upper Limestone (SUL); both have become highly depleted over the time. Conventional drilling technologies in these formations result in complete loss of drilling fluid, stuck pipe & severe formation damage. Pakistan Petroleum Limited (PPL) planned drilling Sui93(M) as a horizontal well in Sui Main Limestone (SML) Formation. Drilling a horizontal well with conventional drilling technology in a depleted formation having 500 psi pore pressure at a depth of ~1400 m (TVD) was a real challenge. Underbalanced Drilling Technology (with DDV & ER-EM-MWD tools) was selected as an alternative drilling method. The main objectives of Underbalance Drilling Operation were to drill to target depth while eliminating fluid losses with associated problems and improve drilling performance. A multidisciplinary team of Drilling Operations experts planned and executed this challenging project. Considering the reservoir pressure of formation, stable foam was selected as drilling fluid for UBD operations. Extended Range Electromagnetic MWD tool was used for directional control along with APWD (Annular Pressure while drilling) sensor for real time Bottom Hole Pressure monitoring. Open hole section (~600 meter) was drilled successfully in Sui Main Limestone (SML) Formation. Integrated efforts of Pakistan Petroleum Limited (PPL) and associated service companies of various disciplines during planning and operation phases of the well led to this successful project. This paper highlights key factors in the underbalanced drilling design phase, operational challenges faced during execution and results of the first well drilled in Middle East region using above mentioned integrated group of technologies. These applications have opened new ventures and opportunities for depleted field developments in the region and particularly in Sui Field of Pakistan.
- Asia > Pakistan > Balochistan > Dera Bugti District (0.35)
- Asia > Pakistan > Sindh > Karachi Division > Karachi (0.24)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock > Limestone (0.86)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.46)
- Asia > Pakistan > Balochistan > Dera Bugti District > Lower Indus Basin > Guddu Block > Sui Field (0.99)
- Asia > Pakistan > Central Gas Basin > Sui Main Limestone Formation (0.98)
Compositional Reservoir Simulation of Adhi Field with Sharp Changes In Oil Gravity with Production
Siddiqui, Fareed (Pakistan Petroleum Limited (PPL)) | Khan, M. Noman (Pakistan Petroleum Limited (PPL)) | Rehman, Zaghum Ur. (Pakistan Petroleum Limited (PPL)) | Bandal, Malvinder (Gaffney, Cline & Associates, Singapore (GCA))
Abstract Adhi field is located in Punjab province of Pakistan in Potwar region and was discovered in 1978. Adhi structure consists of main northeast-southwest (NE-SW) trending popup structure with a relief of ~600m and extensions separated by faults in the NE and southern flanks. So far 10 wells have successfully penetrated Tobra & Khewra reservoirs with most of the wells drilled along the fold axis. The PVT analyses based on the initial wells show the reservoir to contain rich retrograde condensate fluid with an initial condensate to gas ratio of ~150 bbls/MMscfd. Production from the Tobra and Khewra reservoirs started in 1990 with the installation of 25 MMscfd LPG processing plant. The plant capacity was doubled in 2006. The field presents complex geology because of the presence of extensive faulting and high relief structure (600-700m). The field’s production performance is complicated by the variation in the PVT behavior of the produced fluids with production and the presence of possible oil rim. The field is estimated to contain ~1120 Bcf of wet gas and more than 160 MMstb of Liquid Hydrocarbons (Condensate and Oil). The reservoir pressure dropped below the dewpoint in 1992-93 and the reservoirs have been producing below dewpoint for the last 18 years. The most challenging part in planning the further enhancement of production and maximization of recoveries from the reservoirs is the prediction of the composition of production stream in the future. Both the reservoirs are experiencing significant change in fluid properties for the last 5-6 years. The produced condensate used to be transparent, which has gradually turned black with API gravity decreasing in almost half of the wells from the initial 55° to 35°. A three dimensional compositional reservoir simulation study was initiated to have more reliable prediction of the complex compositional behavior of field production. The study has completed the fluid characterization with matching of lab results for saturation pressure, Constant Composition Expansion (CCE) & Constant Volume Depletion (CVD). The tuned Equation of State (EOS) has been used in compositional reservoir simulation for history matching and predictions. However, for matching the high density fluid breakthrough, rigorous tuning of equation of state (EOS) was required. The sensitivity of critical condensate saturations Scc was also being attempted to achieve history match at well level. Reasonable HM of reservoir pressure has been achieved; with change in oil API and CGR & Tubing Head Pressure (THP) with assigned uncertainty range of 10-20% due to the complex nature of reservoir behavior. This paper discusses in depth, the challenges of compositional reservoir simulation, describing formulation of EOS & its subsequent matching, establishing the reservoir fluid gradient & gravity segregation with their impact on HM. The future development strategies are also discussed with the stand point of reservoir management to increase recoveries from such challenging reservoirs.
Production Optimization through Systematic Removal of Formation Damage, A Case Study Eni Pakistan
Heikal, S.. (Eni Pakistan Ltd.) | Santellani, G.. (Eni Pakistan Ltd.) | Sultan, A.. (Eni Pakistan Ltd.) | Mugheri, S.. (Eni Pakistan Ltd.) | Eisa, H.. (Eni Pakistan Ltd.) | Iqbal, J.. (Sprint Oil & Gas Services)
ABSTRACT Formation damage removal using matrix acid stimulation in Sandstone reservoir is recognized as a risky production optimization operation, however, a good understanding of formation mineralogy, root cause of formation damage, and stimulation procedures can help reduce the risk and increase the chance of success. The scope of this paper is to share Eni Pakistan’s workflow which lead to successful matrix acid stimulation campaigns in Bhit, Badhra and Kadanwari fields. Prior to the damage removal operation, the selected wells’ deliverability analysis showed low productivity as compared to the ideal one. To restore the ideal wells’ productivity index, detailed damage analysis was performed as per following workflow. Perform pressure transient test to evaluate and quantify the level of damage Evaluate individual perforation contributions using production logging tools Assess the origin of damage by reviewing the drilling, completion operation Estimate the possible gain in production after removing the damage Define the proper chemical requirements and design the stimulation procedures and perform Post stimulation analysis to optimize the stimulation procedure prior to the next job if required. Seven candidate wells were selected for damage removal operation. The matrix stimulation operation resulted in incremental daily production of up to 160%. The increase in the production rate was accomplished by regaining the wells’ potential deliverability. This helped improve the fields’ reservoir management, accelerating hydrocarbon recovery and adding to the reserves.
- Asia > Pakistan > Sindh > Dadu District (0.48)
- Asia > Pakistan > Sindh > Khairpur District (0.35)
- Asia > Pakistan > Sindh > Khairpur District > Indus Basin > Kadanwari Field (0.99)
- Asia > Pakistan > Sindh > Dadu District > Bhit Field (0.99)
- Asia > Pakistan > Sindh > Dadu District > Badhra Field (0.99)
- Well Drilling (1.00)
- Well Completion > Completion Installation and Operations (1.00)
- Well Completion > Acidizing (1.00)
- (6 more...)
Development of Low Permeability Carbonate Reservoir in Depleted Sand Producing Gas Field - A Case Study
Majeed, Arshad (Oil and Gas Development Company Ltd. Islamabad) | Khan Jadoon, Mohammad Saeed (Oil and Gas Development Company Ltd. Islamabad) | Jahangir, Saleem (Oil and Gas Development Company Ltd. Islamabad) | Andrabi, Aftab Hussain (Oil and Gas Development Company Ltd. Islamabad) | Ahmed, Bashir (Oil and Gas Development Company Ltd. Islamabad)
ABSTRACT Exploration and exploitation of low permeability gas reservoirs in mature developed field is a challenge. It involves re-evaluation and characterization of reservoir properties of the producing zones. As the field understudy is mature and needs to understand the different pressure regimes and available gas potential in depleted and un-depleted zones before embarking on the exploitation of these low permeability reservoir. In past, development of low permeability reservoir was considered uneconomical due to low flow rate and longer pay out time. However, present gas prices and existence of infrastructure of surface facilities on field shifts the negative economics of low gas flow rates to positive direction. Consequently, any gas flow rates are deemed to be economical and a source of extra revenue. In this field, both carbonate and sandstone are producing reservoirs. Carbonates are of low permeability reservoir while sandstone is fragile and represent high permeability reservoir. Initially DSTs were conducted in both reservoirs while wells were completed in sand stone reservoir. Due to the fragile nature of the sandstone formation, gravel pack completion was used to avoid sand production. Initially, high permeability sand stone formation was produced. Volumetric and dynamic data was collected and analyzed to determine the undepleted part of the reservoir. The dynamic data indicated that low permeability reservoir has insignificant contribution and needs to be developed. Petrophysical properties of the carbonate reservoir were reviewed; new DST was conducted in the carbonate reservoir. During DST, longer build up was planned for reliable pressure data. After DST analysis, it was observed that it is low permeability reservoir with high skin value and need to be stimulated. Acid stimulation was carried out that have resulted in significant improvement and the well was put on production with sustainable production rate. In this paper, integrated approach of evaluation of geological and dynamic data that have resulted in successful recompletion of wells in low permeability carbonate reservoir will be discussed. The lesson learned from this successful evaluation and production of low permeability reservoir can be used for the exploitation of these reservoirs in the country.
- Asia > Pakistan > Khyber Pakhtunkhwa > Karak District > Shinawari Formation (0.99)
- Asia > Pakistan > Khyber Pakhtunkhwa > Karak District > Samanasuk Formation (0.99)
- Asia > Pakistan > Sindh > Panjpir Field (0.98)
- Asia > Pakistan > Sindh > Nandpur Field (0.98)
Underground Coal Gasification in Thar Colliers: Encountering the Problems and Solutions for Producing Syngas
Khurshid, Ilyas (PhD student Petroleum Engineering Seoul National University) | Baig, Mirza Abdul (Director Underground Coal Gasification Project Islamkot Thar) | Choe, Jonggeun (Professor Seoul National University)
Abstract The demand of energy in Pakistan is increasing continuously. Fossil fuel mainly coal reserves more than 175 billion tons in the Thar can play a vital role to fulfill energy needs for decades. The Thar Coal field was discovered in 1992 but up till 2010 no serious efforts were made to utilize this huge energy resource. In 2010 Underground coal gasification project was established to develop and exploit the thar coal deposits with underground coal gasification (UCG) technique to convert the in-situ coal to syngas for power generation and for other industrial uses. During construction phase of the underground coal gasification different problems were encountered mainly the hole linkage, water incursion, aquifer characterization and ignition of coal. This study provides the research work made in the field to solve above mentioned problems and presents detail analysis and procedures that how these problems were meet and solved. Finally this study presents characterization of the aquifer and shows from which well ignition should start to produce syngas from Thar coal.
Abstract A fracturing campaign was carried out in Adhi Gas Condensate Field to improve deliverability from selected low productivity wells, some suspected to be suffering from condensate banking. Tobra interval of Adhi12(T/K), the deepest well in the pop up structure, was hydraulically fractured successfully by placing 133,000 lbs of proppant into the formation. Well flow back was conducted yielding disappointing results contrary to the offset well experiences in the field. Despite extensive and continuous nitrogen lifting, the well produced at minimal liquid rates (50bbl/Day) with very high BS&W (80 - 90%). Polymer (Kill/Frac Fluids) induced fracture/formation damage, calcium carbonate pills (LCM) and deposition of organic scales inducing damage and a possible water block were suspected as likely factors restricting the well potential. This paper presents the investigative work, planning and implementation of a remedial treatment that helped successfully revive production from Adhi-12(T/K) Tobra, a well which failed to deliver the anticipated post frac potential. Aromatic Solvents, used in combination with concentrated organic acid and mutual solvents served to create a strong hydrophilic environment in the, now stimulated, critical matrix. Post remedial treatment production from the well resulted in up to 350 BBL/Day of fluids producing at ~60% BS&W. Nature and volume of the high percentage water however proves to be a concern. No Hydrocarbon-Water Contact at the two reservoir levels has yet been encountered in the field.
- Asia > Pakistan (0.31)
- North America > United States (0.30)
- Asia > Middle East (0.29)
- North America > Canada (0.28)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.76)
- Asia > Pakistan > Tobra Field (0.89)
- Asia > Pakistan > Punjab > Upper Indus Basin > Potwar Basin > Adhi Field > Chorgali-Sakesar Formation (0.89)