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Collaborating Authors
SPE/PAPG Annual Technical Conference
ABSTRACT OMV (Pakistan) Exploration G.m.b.H being a performance driven organization has always been keen to improve and optimize its performance by the applications of state of the art technologies. The company operates 5 blocks in the middle Indus basin of Pakistan and is engaged in the drilling of HT gas wells. Core jamming in loose and inter-bedded reservoir pay zones has been a frequent occurrence in the wells drilled in these blocks which motivated the drilling team to seek new and advanced techniques to prevent it from happening. The purpose of this paper is to share the experience of using Anti-Jam Coring System in high temperature gas fields of Pakistan. The main advantage of the system is to save trips and the provision to make up to three attempts in a single run in case jamming occurs while cutting the core. The paper discusses the experience of using this system for the first time for cutting core in exploratory (two) and development (one) wells. On the basis of offset wells, the use of such system was evaluated and then applied successfully to cut core in the in the reservoir sands. Upon recovering core on surface, it was found that the core jamming did occur but the coring job continued until the desired length was successfully cut. At the same interval in offset wells, it was possible to cut limited section of core only before jamming stopped any further coring progress. The use of this system proved its worth as it helped in saving additional trips thereby yielding time and cost benefits to the operator. It is recommended to use in future where similar problems are anticipated.
Effective and Eco-Efficient Pipe Inspection in Heavy Mud Environment Using Induced Electro-Magnetic Measurement (EMDS)
Ahmed, Riaz-ud-Din (Pakistan Oilfield Limited) | Rana, Mohammad Arif (Pakistan Oilfield Limited) | Pamungkas, Andri (Eastern National Oilfield Services) | Sajjad, Irfan (Eastern National Oilfield Services)
Abstract Well AA was spud on December 2008 and drilled to 16,432 ft (side track-2) in the Eocene formation. In 6" hole, 5" liner was set from 15,498 ft – 16,426 ft. During circulation prior to cementing job, the circulation ceased due to plugging and the circulation had to be aborted. In order to find out the reason for plugging cement evaluation log was carried out, which showed strong barite settling behind bottom section of 5" liner. After extending 7" liner to surface, 92 ft (selective) of Sakesar / Nammal & Patala formations were perforated. While homogenizing mud, gas cut was observed, subsequently mud weight was increase to 17.1 ppg. 7" permanent packer with 2-7/8" tail (207’ long) was set at 15,424 ft. Well was completed with 3 ½" tubing along with gauge adaptor and PTSV. 15K Flow head was installed on April 2010. Coiled tubing was run and 17.1 ppg mud in tubing was displaced with 12 ppg to 7,500 ft, observed no flow. Lowered CT down to 10,000 ft and hole volume was displaced with 9 ppg gel when the well started to flow strong gas. The onsite compositional analysis showed 7% H2S. In order to meet the critical differential on 7" casing below the packer, the choke was reduced to 6/64" (WHP 5000-5150 Psi). CT was pulled out of hole. The well was S/I and the WHSIP increased to 10,162 psi. In view of high shut in pressure and the presence of high H2S concentration it was deemed prudent to discontinue the test. Therefore the well was shut-in from down hole PTSV. The tubing string above the PTSV was displaced with 18.2 ppg mud using CT. The tubing along with DGA was pulled out (Max BHP 13,102 Psi and Max BHT 308 °F at 15324 ft). After milling permanent packer, homogenized 18.2 ppg mud against perforations. 5" bridge plug was set at 15,632 ft, capped with cement plug (top of cement at 15136 ft). RIH 3 ½" open ended tubing to 13,158 ft. N/D BOP and N/Up X-Mas tree. Well temporarily suspended and rig released on May 2010. On March 2011 the company decided to bring work over rig to re-complete the well with a new completion string. The integrity of the liner and casing was in question. Some pressure build up was also monitored in annulus between casings. Pipe inspection was needed to evaluate integrity of the liner and casing. The need to monitor the condition of second pipe behind first pipe filled with heavy mud weight (17.2 ppg), eliminated the option of using standard acoustic pipe inspection tool.
ABSTRACT The Potwar region of Upper Indus Basin in Pakistan is well known for its complexities in drilling because of high pressure subsurface conditions at shallow depths and presence of loss circulation zones. Lignite mud system is applicable preferentially in such conditions because of its low cost, inhibitive properties and tolerance to high mud weights. A study has been undertaken to evaluate the characteristic properties of lignite from Lakhra Coal mines, district Jamshoro, Sindh Province as drilling mud additive. The rheological properties, filtration loss and tolerance to high mud weight were investigated using API standard procedures. The results were positive. This paper presents the characteristic properties of lignite from Lakhra for use as drilling mud additive. The study has been carried out in Mud Engineering and Cementing laboratory of Petroleum Engineering Department at NED University of Engineering and Technology, Karachi.
- Asia > Pakistan > Upper Indus Basin (0.99)
- Asia > Pakistan > Punjab > Upper Indus Basin > Potwar Basin > Adhi Field > Chorgali-Sakesar Formation (0.99)
- Asia > Pakistan > Balochistan > Dera Bugti District > Lower Indus Basin > Guddu Block > Sui Field (0.99)
Formation Evaluation Using Wireline Formation Tester (WFT): Case Study of an Exploratory Well in TAL Block Pakistan
Arshad, Safwan (1MOL Pakistan Oil & Gas Co. B.V Islamabad-Pakistan) | Ahmed, Jawad (1MOL Pakistan Oil & Gas Co. B.V Islamabad-Pakistan) | Mughal, Muhammad Haroon (2Schlumberger, Islamabad-Pakistan)
ABSTRACT An exploratory well was drilled in the North West part of TAL Exploration License which penetrated multiple potential formations. Open hole logs were acquired and in view of the open hole log interpretation, Wireline Formation Tester (WFT) was planned to be conducted. Main objectives were to determine vertical pressure profile across the prospective formations of fractured limestone and sandstone nature, to identify fluid/contacts present in different formations and collect representative fluid samples. Based on open hole logs analysis, 30 points/intervals were selected across multiple potential formations for recording pretests using Single probe module and Dual Packer module. During the course of recording WFT log, Real Time data transmission system was also utilized that helped in taking many critical decisions. During the execution of WFT, valuable data was acquired successfully which facilitated in meeting the pre-defined objectives. This paper confers the results & analysis on data congregated during WFT campaign and its part played in formation evaluation and reducing number of DSTs in the well. Transient testing techniques were also employed on data acquired from Dual packer module (Mini DST) for the estimation of flow regimes and reservoir parameters. This paper also presents the comparison of reservoir parameters estimated from WFT-Dual Packer (Mini DST) & CHDST and discusses the possible causes of some of the variations.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.43)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock > Limestone (0.30)
- Well Completion > Well Integrity > Zonal isolation (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Formation test analysis (e.g., wireline, LWD) (1.00)
- (2 more...)
Abstract Every hydrocarbon discovery is not of commercial scale. Once a reservoir is discovered by drilling an exploration well with encouraging results with presence of hydrocarbons, an extended testing period starts to authenticate the in-place hydrocarbon volumes and deliverable rates and gain more knowledge on reservoir driving mechanism, heterogeneity, geometry, etc. which helps to make field development plan and hence the declaration of commerciality. OMV Pakistan GmbH. has two discoveries in year 2007, Tajjal and Latif. Tajjal reservoir was discovered in May 2007 in Gambat Exploration License, whereas Latif was discovered in February 2007 in Latif Exploration License. Tajjal is located in south-east of Sawan gas field and Latif is in south-east of Miano gas field, operated by OMV GmbH. Both Tajjal and Latif wells were suspended for almost a year and half until gas pipelines laid from Tajjal and Latif to Sawan CPP and Kandwari CPP respectively for processing the raw gas. Couple of wells drilled in each discovery based on G&G input before start of EWT period as a part of field appraisal plan. In January 2009, extended well test (EWT), an extended testing period started to confirm the in-place volumes and instigate the field development plan for both the discoveries. EWT is planned to acquire dynamic data for Tajjal & Latif, on average after every 3 months of production a flow after flow test & build-up data have been acquired for estimating reservoir pressure, permeability, type of aquifer & skin factors. Acquired reservoir pressure have substantially used for estimating Gas Initially In Place (GIIP). Gas in-place estimates are made using EWT data by different techniques; P/Z plots, flowing material balance, analytical model, numerical model and well test evaluations. Results from these methods are reasonably comparable. A resolution will be drawn at the end of EWT phase regarding declaration of commerciality and hence full field development.
- Asia > Pakistan > Sindh > Latif Exploration License (0.99)
- Asia > Pakistan > Sindh > Khairpur District > Sawan Field (0.99)
- Asia > Pakistan > Sindh > Khairpur District > Miano Field (0.99)
Gas Well Productivity Enhancement through Re-Perforation
Aftab, M. N. (1Eastern Testing Services, Islamabad-Pakistan) | Qureshi, I.. (1Eastern Testing Services, Islamabad-Pakistan) | Ashraf, M.. (1Eastern Testing Services, Islamabad-Pakistan) | Khattak, K.. (1Eastern Testing Services, Islamabad-Pakistan) | Abdul Jamil, A. H. (1Eastern Testing Services, Islamabad-Pakistan) | Ahmed, S.. (2PETRONAS Carigali (Pakistan) Limited) | Bashir, A.. (2PETRONAS Carigali (Pakistan) Limited)
Abstract The productivity of the perforated wells is controlled by several perforating parameters; perforation length, perforation diameter, degree of the damage around the perforation tunnels, shot density, and perforation phasing angle. In a new well, once the well is perforated and the production is tested, the well is then killed and completed. Even with the used of non-aggressive kill fluid and non-damaging completion fluid, some degree of formation and perforations damages are induced during well killing and completion operations. Reduction of well productivity post completion compared to pre-completion is often observed. The well productivity can be restored by stimulation treatment which is commonly successful practice in carbonate oil reservoirs but this option can be complicated when it comes to sandstone and gas reservoirs. Production enhancement through matrix stimulation on sandstone and gas wells has much lower success rate. This option is even more difficult in cases where reservoir information is limited. Restoring the gas well productivity to the initial pre-completion condition is challenging and most gas wells unable to deliver the expected production. This paper describes a case history of a gas well in sandstone reservoir, where productivity falls dramatically after completion. Proper investigations were carried out through well test evaluations and comparisons to pre-completion tests which showed high degree of formation and perforation damages. Potential root causes from completion activities which contributed to the damages were identified. Several productivity enhancement options were evaluated in order to restore the well productivity. Re-perforation option was selected as the best option with lowest risk to induced further damage to the formation as well as being the most economical option available. Re-perforation was carried out on the same interval as the original perforations using reactive liner perforating technology. Reactive liner perforating technology was used as it is independent of rock properties and wellbore conditions. The technology also has successful track record especially in tight sandstone reservoirs. Post re-perforation well tests indicated significant production rates improvement as a result from successful re-perforation. In addition, the paper summarizes the key learning’s that will assist operators when attempting to enhance gas well productivity through re-perforation.
- Europe (0.94)
- Asia > Middle East > Iraq (0.68)
Abstract Today’s increasing demand for energy calls for a number of different measures to be taken in oil and gas production. The past has seen a considerable number of wells having been shut-in due to poor delivery, if any at all, or failing a commercial scenario. However, these assets gain more and more adherence, but an attractive commercial solution is sought, nevertheless catering for the specific needs and challenges arising from the fields in question. Mature (or brown) fields often suffer from low wellhead pressures, making them unable to flow to the required first stage separation plant. Moreover, as intermediate gathering stations may have been closed in and dismantled due to an overall decreased production, even longer flowlines will lead to a higher pressure demand. Increased water content renders additional challenges because of higher pressure losses. In addition manpower in the fields has been reduced, giving a high rank on availability for new equipment to be installed. Furthermore regional legal frameworks call for stringent environmentally friendly handling of hydrocarbons. Thus, where gas flaring was state-of-the art in the past it is no longer allowed today. Subsequently the past common production scenarios require adjustments to a considerable extent. Multiphase pumps are particularly suited, to help overcoming the above-mentioned issues. Their ability to add energy to the untreated wellstream, while reducing the wellhead pressure creates an entirely different pressure regime in the production system. While downhole inflow performance is enhanced, differential pressure across downhole pumps is decreased and at the very system end the gas delivery pressure is increased.
- Reservoir Description and Dynamics > Improved and Enhanced Recovery (1.00)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring (1.00)
- Production and Well Operations > Artificial Lift Systems > Hydraulic and jet pumps (1.00)
- Facilities Design, Construction and Operation > Processing Systems and Design (1.00)
Successful Approach of Scale Cleaning Using Organic Dissolvers To Delay Scale Re-Deposition at Pariwali Well # 5: A Case Study
Rana, Muhammad Arif (1Pakistan Oilfields Limited, Islamabad-Pakistan) | Ahmed, Riaz-ud-din (1Pakistan Oilfields Limited, Islamabad-Pakistan) | Dar, Afnan A (2Sprint Oil & Gas Services, Islamabad-Pakistan)
Abstract Production drop caused by down hole scale deposition is becoming a serious problem not only in wells producing with high water cut but also in deep, hot, sour gas wells with very low water cuts(trace to 6%). This paper presents a case study of CaCO3 & CaSO4 scale deposition in a sour well in north of Pakistan that resulted in substantial production drop. HCl (15%) was used to dissolve/wash the scale obstruction in the tubular and clean the perforation of well. Although the treatment was successful in dissolving the scale and restoring the production, yet these production gains were lost rapidly. Scale dissolver treatments followed by scale inhibitions were also implemented but no appreciable results were achieved. A detailed in house study was carried out by POL for scale analysis and its removal techniques. Scale monitoring by produced water analysis, gauge cutter runs, production & WHFP fluctuations, gas analysis and review of seven scale cleaning jobs guided to carry out organic scale dissolving job. It was concluded that 15% HCl acid pumped to dissolve the scale precipitate out due to increase in PH and Bi Carbonate decomposition caused by CO2 evolution. Scale removal with organic dissolvers (Acetic acid) proved successful because it maintained low PH which prevented re-precipitation of acid products. With this approach scale re-deposition was delayed ranging from nine days to nine months.
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Constituents > Salts/Sulphates/Scales (0.38)
- Europe > United Kingdom > North Sea > Northern North Sea > East Shetland Basin > Block 3/8 > Ninian Field > Brent Group Formation (0.99)
- Europe > United Kingdom > North Sea > Northern North Sea > East Shetland Basin > Block 3/3 > Ninian Field > Brent Group Formation (0.99)
- Asia > Pakistan > Punjab > Sakessar Formation (0.99)
- Africa > Middle East > Egypt > Gulf of Suez > Gulf of Suez Basin > Ras Budran Field (0.99)
Hydraulic Fracturing Of Tight Gas Reservoir Of Pab Sandstone At POGC Rehman-1
Nizamuddin, M.. (1Polish Oil & Gas Company, Islamabad-Pakistan) | Aizad, Tanweer (2Oil Indus (Pvt.) Limited, Islamabad-Pakistan) | Andress, G. R. (3StrataGen Engineering, Houston) | Korosa, Marko (4Schlumberger, Islamabad-Pakistan)
Abstract POGC Rehman-1 discovered gas from the Pab sandstone in mid-2009. The well had low productivity primarily due to low reservoir permeability. In December 2009, the well’s Upper and Lower Pab zones were fractured, resulting in a four-fold increase in production. Post-frac testing of the zones discovered very little proppant flowback. This paper outlines the history of this successful hydraulic fracturing treatment in the Kirthar region. The document also discusses the detailed job design, fracture modeling, pre-frac production model calibration, and sensitivities to treatment size. A series of fracture designs was developed to evaluate the uncertainty in fracture geometry predictions. The successful stimulation of a low-permeability gas reservoir dictated placing a long conductive fracture. An important aspect of fracture design is fluid selection. The fluid must maintain excellent proppant transport characteristics throughout the pumping sequence, yet break rapidly and cleanly once the treatment is completed. Another important aspect of fracture design: proppant selection. The proppant is basically the life of the fracture and should maintain adequate conductivity throughout the designed exploitation life of the fracture and completion. The fracturing program and the main treatment’s actual execution are presented in the paper. Operational issues are also discussed. One-hundred mesh sand was used to minimize the risks associated with pressure dependent leakoff (PDL) into natural hairline fractures seen on the FMI log. Post-fracture well-testing data was recorded and analyzed. The results were used to quantify the fracture effectiveness.
- North America > United States > Texas (0.93)
- Asia > Pakistan (0.69)
- Geology > Geological Subdiscipline > Geomechanics (0.93)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.60)
- Asia > Pakistan > Sindh > Zamzama Field (0.99)
- Asia > Pakistan > Sindh > Dadu District > Bhit Field (0.99)
- Asia > Pakistan > Punjab > D.G Khan District > Pab Formation (0.99)
- Asia > Pakistan > Balochistan > Ranikot Formation (0.99)
Abstract Volatile oil and gas condensate reservoirs were uncommon before 1930s. Since then they have been discovered with increasing frequency. This is attributed to the increasing drilling depths. Recently there has been a growing interest in these near critical fluids reservoirs. Large number of discoveries made it imperative to implement the relevant methods to deal with such reservoirs. Usual industrial practice in Pakistan is to use the P/Z plot to estimate the GIIP (Gas initially in place). This is the simplest method and does not require the set of PVT properties below the saturation pressure. However the P/Z method is limited in its application to only volumetric depletion type, dry gas, reservoirs. The general material balance equation gives reliable GIIP estimates, since it accounts for all drive mechanisms. Usually general material balance methods are not preferred in gas condensates, because these require standard PVT properties below the saturation pressure. These properties may be computed using Walsh-Towler algorithm, Whitson-Torp (K-value flash) method or Cubic Equation of State (EOS). This paper demonstrates the application of Walsh-Towler algorithm and K-value flash method (Whitson-Torp method) to calculate the standard PVT properties below the saturation pressure for a gas condensate reservoir. Then the application of Havlena-Odeh and Cole plot methods is exhibited to estimate the GIIP. The results are then compared with that of P/Z plot and an 11% over-prediction by P/Z plot was observed.
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Gas-condensate reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reserves Evaluation (1.00)
- Reservoir Description and Dynamics > Fluid Characterization > Phase behavior and PVT measurements (1.00)