This section features industry or work-related photographs submitted by readers. Selected pictures will be published on the website. Be sure to provide your full name, job position, company name, picture location, and a caption for the picture. Recently, I had the opportunity to go onboard the FPSO Armada Claire. Another beautiful sunrise onboard SIEM Helix 2 NS-52, where i-Tech 7 has two remotely operated vehic...
Africa (Sub-Sahara) Bowleven began drilling operations at its Zingana exploration well on the Bomono permit in Cameroon. Located 20 km northwest of Douala, Cameroon's largest city, the well will target a Paleocene (Tertiary) aged, three-way dip closed fault block. The company plans to drill the well to a depth of 2000 m and will then spud a second well in Moambe, 2 km east of Zingana. Bowleven is the operator and holds 100% interest in the license. Asia Pacific China National Offshore Oil Company (CNOOC) has brought its Dongfang 1-1 gas field Phase I adjustment project on line ahead of schedule. The field is located in the Yinggehai basin of the Beibu Gulf in the South China Sea and has an average water depth of 70 m. The field is currently producing 53 MMcf/D of gas and is expected to reach its peak production of 54 MMcf/D before the end of the year.
Africa (Sub-Sahara) Kosmos Energy has made a significant deepwater gas discovery off Senegal. The Guembeul-1 well in the northern part of the St. Louis Offshore Profond license in 8,858 ft of water encountered 331 net ft of gas pay in two excellent-quality reservoirs, the company reported. The results demonstrate reservoir continuity and static pressure communication with the Tortue-1 well, which suggests a single gas accumulation. The mean gross resource estimate for the Greater Tortue complex has risen to 17 Tcf from 14 Tcf as a result of the Guembeul discovery, the company said. Kosmos, the operator, has a 60% interest in the well. Timis (30%) and Petrosen (10%) hold the remaining interest. In Salah Gas has started production from its Southern fields in Algeria.
Africa (Sub-Sahara) Petroceltic International said that the first of up to 24 new development wells planned in Algeria's Ain Tsila gas and condensate field was successful. The AT-10 well, situated about 2 miles from the AT-1 field discovery well, reached a total depth of 6,578 ft. Wireline logs indicated that the expected initial offtake rate would be comparable to the AT-1 and AT-8 wells, both of which test-flowed at more than 30 MMcf/D. Petroceltic is the operator with a 38.25% interest in the production-sharing contract that covers the Ain Tsila output. The remaining interests are held by Sonatrach (43.375%) and Enel (18.375%). Sonangol reported that it has found reserves in the Kwanza Basin of Angola that could total 2.2 billion BOE, including reserves in a block jointly owned with BP. Block 24, operated by BP, holds an estimated 280 million bbl of condensate and 8 Tcf of gas, totaling 1.7 billion BOE, Sonangol said in a statement seen by Reuters.
Africa (Sub-Sahara) Sound Energy identified significant gas shows at the first Tendrara well onshore Morocco. Drilled to a 2665-m measured vertical depth, the well hit a total gross pay interval of 89 m of gas. The full set of well logs are being processed before the startup of rigless mechanical reservoir stimulation operations, which will be followed by a well test. The company is the operator of the well with a 55% working interest.
Africa (Sub-Sahara) Tullow Oil announced in mid-August that first oil has flowed from the Tweneboa, Enyenra, and Ntomme (TEN) fields offshore Ghana, which was on time and on budget for the project's development plan approved by the government in May 2013. The company expects oil output to ramp up gradually through the rest of the year toward a production facility capacity of 80,000 B/D. Tullow is the operator of the TEN fields with a 47.18% stake. Its joint-venture partners are Anadarko (17%), Kosmos Energy (17%), Ghana National Petroleum Corporation (15%), and PetroSA (3.82%). Asia Pacific Rosneft has made a discovery at the PLDD well in the Wild Orchid gas condensate field in Block 06.1 of the Nam Con Son Basin offshore Vietnam. The discovery is being evaluated for the volume of reserves and commercial attractiveness, and there is a potential synergy with the nearby Rosneft-operated Lan Tay production platform, the company said.
Farid, Syed Munib Ullah (Pakistan Petroleum Limited ) | Ahmed, Hassaan (Pakistan Petroleum Limited ) | Mallah, Sohail Ahmed (Pakistan Petroleum Limited ) | Khanam, Mehwish (Pakistan Petroleum Limited ) | Dhawan, Sandeep (WellPerform ApS )
HPHT well environments present design & operational challenges that could potentially translate into well failure with high consequences. Several risk elements can combine into a complex hazard causing serious threat to well design & integrity. Risk elements could be complex downhole environment, material deration, material incompatibility with the completion/packer fluids and other treatment fluids, metallurgy imbalances etc. This case study presents early life production tubing integrity failure highlighting gaps and suggestions to adopt an integrated risk mitigation approach.
A 5,700 m TVD keeper HPHT exploratory well was drilled in north of Pakistan with reservoir pressure, temperature exceeding 10,000 psi and 320oF respectively. Matrix acidizing was required to remove near wellbore damage in the targeted carbonate reservoir. Initial kick start stimulation efforts resulted in tubing-annulus communication indicating compromised CRA super 13CR completion string integrity. Workover followed wherein another early life completion string failure occurred. Consequently, comprehensive analysis was carried out to determine failure root causes using a systematic fault tree analysis approach.
Failure investigation consisted of two broad scopes: a) Scrutinize well design against established industry standards and best practices for HPHT wells and; b) Completion string material metallurgy tests to evaluate compatibilities with exposed well & treatment fluids, bottom hole environment and assessment of all possible risk scenarios that by itself or in combination with other risks could cause material failure. Further, detailed study work included describing bottom hole environment comprehensively, various types of corrosion risk assessments including evaluation of environment assisted cracking risks, acid inhibitor efficiency evaluation, completion/packer fluid selection, fluid compatibility assessment and fluid additives degradation at high temperatures. Mill manufacturing processes, susceptibility of CRA material passive layer because of austenite percentage were also looked-into. Based on systematic approach and extensive in-depth analysis, key observations were drawn. These observations were further investigated with material testing and possible root cause failure risk factors were arrived at. Conclusions were drawn highlighting primary and secondary failure root causes. A new basis of design and qualification protocols was proposed to mitigate various risks to ALARP.
Bari, Abdul (Schlumberger Seaco Inc.) | Dar, Usman (Schlumberger Seaco Inc.) | Zubair, Talha (Schlumberger Seaco Inc.) | Sarili, Mahmut (Schlumberger Seaco Inc.) | Siddiqi, Sarmad S. (Pakistan Petroleum Limited) | Hammad, Muhammad (Pakistan Petroleum Limited) | Jalil, Talha (Pakistan Petroleum Limited) | Siddiqui, Suhail Ahmed (Pakistan Petroleum Limited)
Over the years, wireline formation testers have been frequently used for evaluation of near wellbore reservoir characteristics using mini-DST technique. Its primary applications are especially in case of tight or laminated layers where conventional testing approach is time consumingin terms of rig time and associated cost. Such evaluation helps client in optimizing their completion strategies. One such successful application of mini DST technique has been in Kandhkot field; which is sub divided into three domes having three reservoirs Sui Main Limestone (SML), Sui Upper Limestone (SUL) and Habib Rahi Limestone (HRL). Formation evaluation which included core analysis and open hole logs; was carried out in surrounding wells encountering SUL and it showed relatively less porosity and permeability in West dome (Ф=8-12% and K=0.1–1.68mD). Testing on two wells confirmed gas presence but its potential could not be established due to low rates. To address this challenge, wireline formation testing technique with straddle packers was opted in a well KDT X, encountering SUL formation. By successful utilization of Mini DST, Operator managed to evaluate critical reservoir parameters for characterization of all individual layers, which helped in better reserves estimates and reservoir modeling.
Wireline formation testing has been in use for several decades now. Advancements in wireline formation testers have led to an effective reservoir evaluation through its various answer products. Reliable pressure and mobility measurements, fluid gradients and contacts, downhole fluid analysis and PVT sampling, vertical interference testing and reservoir characterization are few to count.
Complex lithology, naturally fractured carbonates, multiple reservoir sections and various reservoir heterogeneities present significant challenges for formation evaluation. Generally, it takes several days to weeks to test multiple formations separately; which can lead to increase in associated cost. One of the efficient approaches in such situations is to utilize wireline formation tester tools which can provide an opportunity to test multiple formations during same run. For downhole testing of laminated, tight or fractured formations, a straddle packer (commonly known as dual packer module) is used to isolate the interval of interest; followed by series of controlled drawdowns and buildups to perform pressure transient analysis, known as Interval Pressure Transient Testing (IPTT).
Ashraf, Qasim (Weatherford International Ltd) | Khalid, Ali (Weatherford International Ltd) | Ali, Farhad (Weatherford International Ltd) | Luqman, Khurram (Weatherford International Ltd) | Mousa, Ayoub (Weatherford International Ltd) | Babar, Zaheer Uddin (Pakistan Petroleum Limited) | Hussam Uddin, Muhammad (Pakistan Petroleum Limited) | Ullah, Safi (Pakistan Petroleum Limited)
An operator has drilled more than 32 wells to date in Adhi field, a gas and condensate field in northern Pakistan. The majority of these wells produce from depleted sands and some also produce from limestone reservoirs. The wells range in depth between 8,366 and 11,483 ft (2,550 and 3,500 m).
The operator was in the process of drilling the 8 1/2-in. hole section with the least possible mud weight to minimize the overbalance across the lost-circulation-prone limestone formation. While drilling the section, an unexpected gas pocket was encountered and subsequently required an increase in mud weight. To further add to already challenging drilling conditions, a fault was expected in the middle of the section. This fault was expected to produce total losses. The resulting loss of hydrostatic head would have caused a troublesome well-control scenario.
The above conditions led to an inherently tight drilling window. The operator thus made precise management of wellbore pressures a prime objective. However in conventional drilling, relying on the mud weight and pumping rate for accurate management of wellbore pressures proves highly inefficient, if not impossible.
A managed pressure drilling (MPD) and underbalanced drilling (UBD) hybridized system was devised to enable drilling the 8 1/2-in. hole section. An MPD system that applies constant bottom hole pressure would enable drilling the section with the least possible mud weight and as close as possible to the pore pressure line. In the event that heavy to total losses were encountered because of the predicted fault, the system could be switched over to UBD flow drilling. By switching over to UBD, the equivalent circulating density (ECD) would be reduced further and allow the well to flow while drilling and mitigating losses.
An MPD and UBD system was also expected to offer numerous benefits in drilling, including reduced chances of differential sticking, reduced formation damage, increased rate of penetration and bit life, less washouts in the drillstring and pumps, reduced nonproductive time, and enhanced abilities to execute well control with the pipe in motion without fear of getting stuck.
The MPD and UBD hybrid system was deployed to the location. The operator was able to drill the 8 1/2- in. section to the target depth. The operator commenced drilling with an MPD system but, as expected, heavy losses were encountered. Drilling then proceeded with UB flow drilling until reaching target depth. The hybrid system enabled the operator to achieve target depth, eliminate an entire casing string, and substantially reduce NPT. This paper discusses the planning, design, and execution of the MPD and UBD hybrid system.