This course discusses the fundamental sand control considerations involved in completing a well and introduces the various sand control techniques commonly used across the industry, including standalone screens, gravel packs, high rate water packs and frac-packs. It requires only a basic understanding of oilfield operations and is intended for drilling, completion and production personnel with some sand control experience who are looking to gain a better understanding of each technique’s advantages, limitations and application window for use in their upcoming completions.
Hao, Qian (Exploration and Development Research Institute & Science and Technology Department of Changqing Oilfield Company, CNPC) | Wang, Jiping (Exploration and Development Research Institute of Changqing Oilfield Company, CNPC) | Han, Dong (Science and Technology Department of Changqing Oilfield Company, CNPC) | Li, Wuke (Exploration & Development Research Institute of Changqing Oilfield Company, CNPC) | Liang, Changbao (South Sulige Operating Company of Changqing Oilfield Company, CNPC) | Dai, Libin (South Sulige Operating Company of Changqing Oilfield Company, CNPC) | Jia, Yonghui (South Sulige Operating Company of Changqing Oilfield Company, CNPC) | Qi, Congwei (TOTAL) | Zhai, Gaoqiang (TOTAL)
South Sulige operation project is an international cooperation development of tight sand gas field located in the Ordos Basin, Northwest China. The economy of the project relies on technical breakthrough to select good drilling location for getting higher Estimated Ultimate Recovery (EUR) rather than partners continually reducing annual investment and cost saving to survive in the global oil price fluctuations in the long run.
Although a total of 306 wells have been drilled and 1648 Km2 of 3D seismic data have been acquired and processed during the past 3 years, well drilling results were not as good as expected in terms of seismic sand thickness prediction and channel sand / shale discrimination. Seismic data quality indeed improved due to large efforts of the processing, even getting clear seismic images at reservoir level, however, at Upper Permian He8 Formation, the main gas producing target layer, seismic interpretation results are still difficulty to distinguish complicated fluvial depositions of this tight sand gas filed.
On the other hand, existing production data indicate that Absolute Open Flow (AOF) of the super good well which accounts for only 3% of the total drilled wells usually exceed 120×104m3/d, annual production of the super good well could exceed 2500 ×104m3, EUR of the super good well may exceed 2.4×108m3. Compared with the ordinary well, EUR of the super good well is 9.6 times that of the ordinary well. As a result, accurate predicting good drilling location and try to capture more super good wells remains the biggest challenge and the most attractive research direction for this international cooperation project.
Therefore, a different approach joint 3G (Geophysics, Geology, Gas Reservoir) integrated study is carried out by an international joint research team from Paris, France and Xi’an, China. This paper shows a new method of combining sedimentological model from wells results (static data include core description, typical channel E-logs parameters, semi-regional synthesis. dynamic data include AOF, annual production, EUR) with low value of Poisson's Ratio (PR) / amplitude maps which were defined in the study, aiming to identify areas where a given dominant fluvial facies could be predicted.
The paper's objective is to share the integrated study approach to get better understanding of such tight sand reservoir, and the proposed methodology opens new opportunities for predicting good drilling location, increase the probability of capturing more super good wells, lower the project development risk with best practices approach.
Zaini, Muhamad Zaki (Schlumberger) | Du, Kuifu (Schlumberger) | Zhu, Ming (Schlumberger) | Feng, Li Jun (Schlumberger) | Yang, Hai Hua (Schlumberger) | Wei, Lin (Schlumberger) | Liu, Yi (Schlumberger)
Yanbei Project is a tight unconventional gas development that covers a vast area of 2,341 km2 in the Ordos basin – the largest gas producing basin in China. The paper outlines the innovative technologies applied, major achievements and the integrated approach used to successfully develop this large-scale gas greenfield of highly heterogeneous fluvial thin sands with very complicated surface terrains and resources overlaying issues (coal mines and water reservoirs). The project scope calls for drilling and fracturing 784 wells in the full field development in two phases. Phase 1 includes construction of 7 hubs, central processing facilities (CPF), and 360 km of pipelines on a complex hilly topography and aims to deliver production of 1.4 bcm/year. Phase 2 will ramp up to a higher rate. The horizontal well with multi-stage fracture development concept was introduced for the first time in the project and has significantly improved both single well productivity and project economics. More than 20 different technologies, ranging from subsurface, drilling, logging, completion, stimulation, production and facilities, have been applied each of which has been carefully assessed to ensure its value to the project. The advanced 2D seismic technologies have enabled the project to successfully reprocess and interpret a complicated 2D seismic dataset that is heavily distorted by the hilly terrains. The integration of the 2D seismic interpretation with a variety of subsurface and drilling datasets have enhanced the understanding of reservoir characterization and sandbody architectures hence significantly reduce geological risks in drilling horizontal wells in such a complex fluvial system. The drilling and surface engineering work have dealt with a variety of different challenges such as well pad acquisitions, conflicting with coal mines & surface water reservoir areas along with local community issues. One of the key success factors for the project is the integration of the industry's worldwide expertise of technologies, procedures and HSE standards coupled with the local experience, which has ensured an innovative and fit-for-purpose technology-driven solution in planning and execution of the project. The paper describes the main geological and engineering challenges and outlines an integrated approach in applying extensive but selected technologies to resolve those challenges.
Tong, Zheng (Research Institute of Petroleum Exploration & Development, PetroChina) | Wang, Yongming (ChangQing Oilfield Company, PetroChina) | Wei, Ran (RIPED, PetroChina) | Xue, Jianjun (RIPED, PetroChina) | Li, Ming (RIPED, PetroChina) | Qian, Jie (RIPED, PetroChina) | Shen, Zejun (RIPED, PetroChina) | Zhang, Yanming (ChangQing Oilfield Company, PetroChina)
Water-swellable packer (WSP) is used rather than oil-swellable packer (OSP) for open-hole packer-sleeve (OHPS) fracturing and completion in China. In this paper, the two improved WSPs including hybrid external casing packer (ECP) and WSP with corrugated packing element are developed to solve the problem of tripping and deployment in irregular horizontal wellbore. The hybrid ECP combines mechanical-set packer with water-swellable packing element. The WSP with corrugated packing elements makes structure more compact than the traditional packer.
The two solutions were successfully evaluated by bench test. The former combines the feature of high-rating sealing performance, instant fracturing operation with swelling-assistant isolation. The latter has advantages of smaller size, high reliability and easy tripping over traditional WSP.
During OHPS multistage fracturing trial in Sulige gas field, the first five-stage operations are performed with hybrid ECPs and the last two-stage fracture diversion treatment are performed with new WSPs. The fracture diversion was carried out by injecting temporary plugging agents (TPA). The sealing effectiveness is fully validated by long-time ambient pressure differential during fracture diversion. It is shown from field operation that the new OHPS based on improved ECPs is able to meet the requirements of completion and stimulation in irregular horizontal wellbore for tight sandstone reservoirs.
Zhang, Xiangning (Petrochina Co.Ltd.) | Zhang, Minglu (Petrochina Co.Ltd.) | Ge, Chunmei (Petrochina Co.Ltd.) | Deng, Huaiqun (Petrochina Co.Ltd.) | Wang, Hongyu (Petrochina Co.Ltd.) | Gong, Bentao (Petrochina Co.Ltd.) | Zhang, Xiaofeng (Petrochina Co.Ltd.)
Tight gas is an important resource for PetroChina's foreign cooperation business. PetroChina has cooperated with Shell and TOTAL in tight gas E&P in Ordos basin for years and has made great achievements. It was proved through years of exploration that sets of reservoirs occurred in the Perm-Carb system of the Ordos basin. Benxi, Taiyuan and Lower Shanxi formation are accumulated in marine environment and characterized by sandstones encased in mudstones, while the Upper Shanxi, Shihezi and Shiqianfeng strata are the continental deposits as the favorable targets in the basin.
CB is a cooperation project with Shell in northern Ordos basin. The Permian Shanxi tight gas interval was its target reservoir. CB is the first project deploying dual-lateral horizontal wells to explore the low permeability massive gas field in China and achieved big success. By far, the project has maintained annual production on a high level for 8 years. The second phase appraisal was initiated in 2013 to explore the secondary reservoirs. Recent testing result has seen a good indication and will be very helpful to raise total output to a new level. South Sulige gas field is located in the northwestern Ordos basin and is a project cooperated with TOTAL. To meet the challenges of poor lateral continuity and low reserve richness, an integrated new approach, such as reservoir prediction from 3D seismic Poisson ratio, "chessboard" well patterns from pad development, factory mode drilling and completion operations, were employed which effectively improved well performance and operational efficiency. PetroChina also initiated a joint study with ExxonMobil in Changdong area. The reserves were classified and individual well EURs were estimated by comparing with the U.S. Piceance basin and tight gas E&P practices in Ordos basin. The effective recovery of marginal pay sands will be crucial to the economic.
Total gas consumption in China grew by 7.4% and gas production grew by 6.1% in 2014. Being the largest O&G supplier, PetroChina produced 74.4% of the total national output in 2014. Tight gas accounted for 28% of total annual gas production in PetroChina. Annual natural gas production from foreign cooperation projects reached 6.55 bcm with more than 82% from tight gas reservoirs. Ordos basin, Sichuan basin and Tarim basin are all rich of tight gas resources. Foreign cooperation in tight gas resources in China is enjoying a favorable development circumstances and embracing its bright future.
Sulige gas field is a typical tight gas reservoir with the features of low-pressure, low-permeability and low-abundance. Its gas-bearing condition is bad so that the economic benefit is not good. To improve the well performance and economic benefit, an applicable well-plant operation model which includes the design optimization, the technology template, the streamline operation, the standardized regulation, the resources generalization and the integral management is established through continuous explorations and practices.
This paper describes the successful well-plant operation model conducted in block Su53 along with the pilot project in block Su11. The well-plant operation model increases the operation efficiency, shortens the drilling period and saves the cost. 8 vertical wells are drilled in the pilot project in Su11, which takes 6 days to be fractured and bring great economic benefit. In addition, the well performance is significantly improved compared with other vertical wells in the block Su11. The pilot project provides experiences for the well-plant operation model in block Su53. 13 wells which include 10 horizontal wells, 2 directional wells and 1 vertical well are drilled in a 200m×300m well pad, lining in two arrays. The target formations are H8 and S1, ranging from 3150m~3500m. The whole job including well pad construction, drilling, completion, fracturing, gas testing and production for all 13 wells is finished in only 210 days. Compared with the conventional single-well job, the well-plant operation model saves a lot of time and money. The environmental protection is enhanced. The development model of the block Su53 is very successful and the well-plant operation model receives much attention in China. The successful application of the model provides invaluable experience for the development of tight-gas sands and shales in China.
Wong, A.K. (Schlumberger) | Judd, T.C. (Schlumberger China SA) | Palacio, J.C. (PetroChina Changqing) | Wong, K. (PetroChina Changqing) | Fan, W. (PetroChina Changqing) | Grimbert, B. (Total E&P China) | Wang, Q. (Total E&P China) | Hu, L. (PetroChina Changqing)
A field development project in the central part of the Ordos Basin began in 2011 with the intent to develop commercial production from the two main gas producing intervals. The gas layers within the Shihezi and Shanxi Formation within the South Sulige field are low permeability (0.1 mD) with moderate volumes of gas in place that require hydraulic fracturing to be commercially viable. The early application of technology to minimize development costs and surface impact included multiwell pad-drilling to enhance drilling, completion, and operational efficiency. Fracturing cycle times were reduced by the implementation of multiwell hydraulic fracturing processes, while not compromising well productivity.
To date, 33 well pads have been completed which represents more than 280 vertical wells and 13 horizontal with more than 600 hydraulic fracturing stages being done within the previous three years. The wells completed have encountered a largely heterogeneous field that has resulted in a sizable amount of data being collected.
To improve on this phase of the project, a fieldwide study of fracturing performance has been performed and includes the quantification of dimensionless productivity index (
This paper will discuss the optimization of the fracturing design through use of
Zhang, Jing (PetroChina Xin Jiang Oilfield Company) | Jiangwen, Xu (PetroChina Xin Juang Oilfield Company) | Jiang, Hong (PetroChina Xin Juang Oilfield Company) | Judd, Tobias Conrad (Schlumberger) | Liu, Yuan (Schlumberger) | Liu, Hai (Schlumberger) | Palacio, Juan Carlos (Schlumberger)
The early development of a systematic approach to well completion practices centralized around multistage hydraulic fracturing treatments is often the critical component to sustainable reservoir exploitation and development. Unfortunately, the exploitation of either exploratory or underdeveloped resources often has a number of issues that include the understanding of geological heterogeneity with different results observed within close proximity and the need to optimize completion techniques to offset the potential rapid decline in well productivity. For these cases, well completion and stimulation practices are of utmost importance with the optimization and evaluation of such designs to include and account for the integration of all reservoir and geomechanical parameters. Recent vertical well results from initial exploratory wells combined with single-well horizontal pilot wells has accelerated the development plans for the Jimusaer field located in the Junggar basin of western China. This field covers a surface area of 300,000 acres with the targeted reservoir being located between 2,300 to 4,255 m true vertical depth (TVD). The application of horizontal wells from multiwell pads with each well consisting of up to 23 hydraulic fracturing treatments was meant to exploit large volumes of hydrocarbon reserves that were previously thought unattainable. Operationally, the first four wells consisted of 62 hydraulic fracturing stages and were executed within a 28-day period. The project included the application of an integrated workflow including reservoir characterization along the length of the horizontal well lateral, deployment of novel multistage openhole completion techniques with dissolvable isolation technology, factory fracturing approach with all stages being monitored by microseismic monitoring, and application of chemical tracers on selected stages to identify zonal contribution during flowback and cleanup operations. This paper describes how the acquisition of crucial reservoir and fracturing data combined with operational performance can identify areas for improvement of future completions while strengthening existing ones. 2 SPE-172981-MS Figure 1--Location of Jimusaer field in the Junggar basin of northwest China.
Liu, S. (South Sulige Operating Co.) | Fan, W. (South Sulige Operating Co.) | Falxa, P. (South Sulige Operating Co.) | Wang, Q. (South Sulige Operating Co.) | Liu, H. (Schlumberger) | Wong, A. (Schlumberger) | Zhang, N. (Schlumberger) | Wong, K.S. (Schlumberger)
A joint venture project in the South Sulige gas field began in 2011 with the intent of developing efficient production in the field. The South Sulige gas field has two main producing formations, both with low permeability and porosity. Like many other tight gas sandstone formations in China, fracturing is necessary in order to get economic production in pad-drilling
To date, five wells horizontal and 60 vertical wells have been stimulated in the South Sulige field in this project including four vertical wells from an earlier campaign in 2008. The 2008 campaign had nearly 40% rate of premature screenouts and the first two wells in 2011 also experienced screenouts. Tracing the root of the problem to natural fissures in the formation, mitigation was taken that led to the elimination of premature screenouts since implementation. Post-frac well performances of the new wells have far exceeded production of wells previously drilled in the South Sulige field in 2008. This significant increase can be traced to a complete fracturing methodology that optimizes every step of fracturing design and execution.
The use of specialized multi-stage completions in the horizontal and vertical wells allows the operator to efficiently execute fracturing jobs while also minimizing downtime before flowback, cleanup, and ultimately production. Optimized fracturing designs minimize excessive height growth seen in previous work done in the field along with a new design workflow raise the potential production possible. The fluid design allows for rapid flowback and clean-up to minimize fracturing polymer formation damage. It also contains specific mitigation measures to combat the natural fissures observed in the formations throughout the field.
This paper will discuss the overall enhanced performance achieved through optimization of the fracturing work flow. The discussion will mainly focus on the different completion designs utilized for efficicent multi-stage fracturing in the horizontal and vertical wells, the optimized fracturing stimulation design and new design workflow, clean-up procedures to minimize formation damage, and mitigation of the natural fractures that are abundant in the formations of the South Sulige field.
The Sulige field is located in Inner Mongolia and was discovered in 2001. The depositional environment is a braided channel system with many gas pockets. The South Sulige project began in 2007 with the drilling of two exploration wells and continued into 2008 with three more exploration wells. Using the information and experience gathered in this exploration phase, development of the field started in 2011.
The South Sulige field has two main producing gas formations, Shan1 and He8. They are tight gas sandstone formations, with low overall permeability and porosity. Hydraulic fracturing is required in order to obtain meaningful production from both of these formations. Pad drilling of deviated wells has been adopted as the main production method for this field. Horizontal wells are also being drilled and produced to investigate the potential benefits.
South Sulige block, located in the Ordos Basin in China, is classified as Tight Gas Reservoirs with permeability ranging from 0.01 md to 2 md and porosity rarely exceeding 10%. Potential gas production intervals were identified in the Shihezi Formation and Shanxi Formation.
Four of the existing hydraulically fractured wells, were re-tested by Total.
Total drilled four new wells on this block, stimulated them with hydraulic fractures and performed extensive tests.
The main objectives of well testing were:
1. To reduce the uncertainties on well productivity, mainly permeability and skin.
2. To characterize reservoir extension: no flow boundaries, channel width.
3. To estimate the dynamic connected volumes which are linked to the extent and interconnectivity (amalgamation) of the sand bodies (fluvial sand bars/channel width).
Extended dual build-up tests were designed (from 8 to 18 months) ended by a long duration build-up (from 3 to 10 months) to characterize well productivity and connectivity. As no signature of radial flow, appeared on derivatives, permeability-thickness values were strongly uncertain. Dual build-up tests were designed to allow us to reduce uncertainties on permeability-thickness product. The test analyses have revealed the presence of channel margins to match transient depletion between build-ups.
The results of these extended tests highlighted that channel widths determined by pressure transient analysis were much smaller than expected, compared to outcrop description, except for one well (Y3). This implies that internal heterogeneities, not visible on outcrops, play a major role in the well drainage. These results have to be taken into account to optimize the development scheme, combining the good productivity in the Y3 area and more standard well behaviour elsewhere.