Because of the great heterogeneities and small scale of the Fracture-Cavity type carbonate reservoir, it always needs a high precision seismic data as reference in the drilling. But restricted to the precision of the seismic velocity field and the migration algorithm, the image results always inevitably have large or small misfits. And this misfits always decides the successes and failures of the well. So it is a very good choice to use the seismic guide drilling (SGD) technique to correct the misfits while drilling. Most of the SGD techniques are based on seismic while drilling (SWD) technique which always need long working time and high consumption of equipment. A more simple and economical SGD method is presented here, which mainly uses a wireline VSP measurement before about 300m ahead of target layer to replace the seismic while drilling(SWD) method. By this way, we can obtain a credible T-D relationship and VSP velocity to constrain the seismic velocity field in later processes to get a high precision seismic data. The SGD has been proved by 7 wells and achieved a big success in Tazhong oil field of Tarim basin.
Presentation Date: Wednesday, September 27, 2017
Start Time: 11:25 AM
Location: Exhibit Hall C/D
Presentation Type: POSTER
Zhang, Jianwei (BGP, CNPC) | Ma, Peiling (BGP, CNPC) | Liu, Yonglei (BGP, CNPC) | Dongming, Ling (BGP, CNPC) | Li, Xiangwen (BGP, CNPC) | Xin, Luo (BGP, CNPC) | Shuzhen, Li (BGP, CNPC) | Xu, Bo (BGP, CNPC) | Haifeng, Li (BGP, CNPC) | Yingfu, He (BGP, CNPC) | Wang, Xiongfei (BGP, CNPC) | Zhenzhou, Li (BGP, CNPC) | Wang, Lei (BGP, CNPC) | Leli, Wang (BGP, CNPC)
Fractured-vuggy carbonate hydrocarbon accumulations are the main reservoirs type in Ordovician formation in Tazhong oil field of Tarim basin and many high-productivity wells have been discovered. Years of hydrocarbon exploration here proves that strike-slip fault systems play an important role in controlling development of fractured-vuggy carbonate reservoir and hydrocarbon migration. After systematic study about strike-slip fault systems, it is thought that three strike-slip fault systems mainly developed here, including transtensional type, transpressional type and "X" type. Transtensional type is most in favor of forming fractured-vuggy carbonate reservoir and hydrocarbon migration. Also, we firstly recognize two kinds of typical transpressional-type sinistral strike-slip faults, which are characterized by obvious segmentation in strike direction. Local faults developed within each segment frequently show flower structures in profile, and show a variety of combined styles such as linear horst and graben, en-echelon normal faults, pull-apart graben, horse tail faults on the plane. Study also reveals that cave carbonate reservoir mainly developed within influence range of the large scale strike-slip fault systems. Development degree of cave reservoir and oil and gas enrichment degree are very different in each segment along strike of strike-slip fault. In principal displacement zone, oil and gas is not easy to accumulate and protect. However, oil and gas is frequently rich in terminal zone of the strike-slip faults due to that minor faults most developed here characterized by combination styles of en-echelon normal faults, pull-apart graben and horse tail faults often result in formation of cave reservoir.
Presentation Date: Wednesday, October 19, 2016
Start Time: 11:35:00 AM
Presentation Type: ORAL
Chen, Tao (Nalco Champion, An Ecolab Company) | Chen, Ping (Nalco Champion, An Ecolab Company) | Montgomerie, Harry (Nalco Champion, An Ecolab Company) | Hagen, Thomas (Nalco Champion, An Ecolab Company) | Benvie, Ronald (South West Petroleum University) | Guo, Qi (Robert Gordon University) | Anyanwu, Uche (Nalco Champion, An Ecolab Company) | Xu, Bo (Nalco Champion, An Ecolab Company) | Yang, Xu
Turbulent flow, especially around chokes, downhole safety valves and inflow control devices, favors scale deposition potentially leading to severe loss of production. Recently, scale formation under turbulent conditions has been studied and progressed, focused on the bulk precipitation (SPE164070) and a small bore valve loop test (SPE 155428). However, bulk precipitation is not fully representative the surface deposition in the fields and the Reynolds number of modified loop is unknown. The relationship between a measured Reynolds number and surface deposition up until this study has not been addressed.
A newly developed test methodology with rotating cylinder has been applied to generate high shear rate and evaluate surface deposition with Reynolds numbers up to ~41000. The relationship between Reynolds number and surface deposition is addressed. Using this highly representable test method for BaSO4 scale deposition, several different generic types of inhibitor chemistries, including polymers and phosphonates, were assessed under different levels of turbulence to evaluate their performance on surface deposition.
The results showed it is not always true that higher turbulence results in higher dose of inhibitor being required to control scale. It is inhibitor chemistry and mechanisms dependent. The scale inhibitorscan be classified as three types when evaluating the trend of mass deposition versus Reynolds number and the morphology of the crystals deposited on the metal surface. ? Type 1: Crytal growth inhibitors. The mass of surface deposition increases with the increase of turbulence, along with smaller crystals. ? Type 2: Dispersion and crystal growth inhibitor. The higher the turbulence, the less mass deposition, along with smaller crystals. ? Type 3: Dispersion scale inhibitors. The higher the turbulence, the less mass deposition. The size of the crystals has no major change.
? Type 1: Crytal growth inhibitors. The mass of surface deposition increases with the increase of turbulence, along with smaller crystals.
? Type 2: Dispersion and crystal growth inhibitor. The higher the turbulence, the less mass deposition, along with smaller crystals.
? Type 3: Dispersion scale inhibitors. The higher the turbulence, the less mass deposition. The size of the crystals has no major change.
This paper gives a comprehensive study of the effect of flow condition on the scale surface deposition and inhibition mechanisms. In addition, it details how this methodology and new environmentally acceptable inhibitor chemistry can be coupled to develop a chemical technology toolbox that also includes techniques for advanced scale inhibitor analysis and improved scale inhibitor retention, to design optimum scale squeeze packages for the harsh scaling conditions associated with turbulent flow conditions.
Xu, Bo (a South West Petroleum University) | Chen, Tao (b Nalco Champion, an Ecolab Company) | Chen, Ping (b Nalco Champion, an Ecolab Company) | Montgomerie, Harry (b Nalco Champion, an Ecolab Company) | Hagen, Thomas (b Nalco Champion, an Ecolab Company) | Guo, Qi (a South West Petroleum University) | Yang, Xu (a South West Petroleum University)
The calcium and bicarbonate ions, present in the produced waters in the oilfields, are two major scaling ions in CaCO3 formation. In the last decade, a lot of studies have been focused on the thermodynamic or kinetics of CaCO3 formation, including the effects of scaling ions, temperature, pH, pCO2, etc. Seldom studies are focused on the kinetics of calcium carbonate surface deposition with different levels of calcium and bicarbonate, especially in the presence of scale inhibitors.
In the work reported herein, dynamic loop tests were carried out to study the kinetics of CaCO3surface deposition in three typical produced waters (Water-1, high calcium and low bicarbonate; Water-2, medium calcium and medium bicarbonate; Water-3, low calcium and high bicarbonate) with same saturation index (SI) at 150°C. Typical scale inhibitor chemistries, including phosphonate, polycarboxylic, polymaleic, polysulphonate, polyacrylic, polyaspartate based scale inhibitors, have been tested in three tested waters.
The following conclusions are drawn based on the test results. SI generated by applied prediction software is a parameter indicating the thermodynamic driving force. The kinetics of scale formation, more representative field conditions, should be studied as well to give a guideline of scale formation in the fields. Comparison of calcium, bicarbonate is the dominant kinetic factor for CaCO3 formation in the absence and presence of inhibitors. Higher bicarbonate water, higher minimum inhibitor concentration (MIC) is requested, even the three tested waters with a same SI. The ranking of the performance of scale inhibitor are dependent on the water chemistries and inhibitor chemistries. Some of the best ranking phosphonates in Water-1 and Water-2 with low and medium bicarbonate showed poor performance on Water-3 with high bicarbonate. Some polymers showed contrary ranking performance.
SI generated by applied prediction software is a parameter indicating the thermodynamic driving force. The kinetics of scale formation, more representative field conditions, should be studied as well to give a guideline of scale formation in the fields.
Comparison of calcium, bicarbonate is the dominant kinetic factor for CaCO3 formation in the absence and presence of inhibitors.
Higher bicarbonate water, higher minimum inhibitor concentration (MIC) is requested, even the three tested waters with a same SI.
The ranking of the performance of scale inhibitor are dependent on the water chemistries and inhibitor chemistries. Some of the best ranking phosphonates in Water-1 and Water-2 with low and medium bicarbonate showed poor performance on Water-3 with high bicarbonate. Some polymers showed contrary ranking performance.
This paper gives a comprehensive study of the kinetics of CaCO3surface deposition considering the effects of calcium and bicarbonate, including prediction, laboratory evaluation, mechanisms and inhibitor selection. It will contribute to understand the kinetics of CaCO3 formation and recommend effective inhibitors for field application. Environmentally acceptable inhibitors have been developed for different CaCO3 water chemistries at elevated temperature and are suitable for applications through squeeze treatment or continuous injection.
Prediction of deeply buried (5,000-6,000 m), ultrathin (1–4 m) sandstones is critical to successful exploration and development of a large, subtle hydrocarbon accumulation in the Yudong area of the Kuqa Depression, Tarim Basin, China, as well as other basins. In this study, a geostatistical inversion approach was applied to improve areal mapping of very thin sandstone reservoirs in a Paleocene depositional sequence. We used a high-quality 3D seismic data set with sparse well control. Reasonable stratigraphic and depositional facies analysis established the framework necessary for the inversion workflow. A realistic statistical model (variogram type and range) was selected using a stochastic simulation of multiple combinations of parameters. Results were a significant improvement over those of the previous spark-spike inversion and have been used successfully in local exploration.
In this paper, a new concept of ETLP has been proposed. It is composed of four square columns and a ring pontoon which is consisted of four box beams. The new platform has lesser blocks and welds compared to ETLP, so it can be built at a lower cost and in a shorter construction period. Meanwhile, the pontoon extensions in the new platform is part of pontoons, therefore, the fatigue problem in the welds at the root of extensions in ETLP is solved. A hydrodynamic analysis is conducted to prove the structure’s dynamically stabilities. The results showed the new design has a reasonable hydrodynamic characteristic.
Zhu, Guowen (Daqing Oilfield Co,. Ltd.) | Sui, Xinguang (Daqing Oilfield Co,. Ltd.) | Liu, Bing (Daqing Oilfield Co,. Ltd.) | Xu, Bo (Tong Oil Tools Co., Ltd.) | Wang, Mingsheng (Daqing Oilfield Co,. Ltd.) | Xiang, Weiqing (Daqing Oilfield Co,. Ltd.) | Liu, Lihong (Daqing Oilfield Co,. Ltd.)
Daqing Oilfield is a continental deposit oilfield with multi-layers. It has entered a high water cut development stage, its tertiary infill wells mainly develop the formations with effective thickness less than 0.5m and a low permeability less than 0.05 Darcy, this kind of layers usually perform a low conductivity. Technically, this formation requires a better completion method. Being previously used on high permeability formation with small aperture and short penetration, the perforating bullet could not meet the completion requirement in such a low permeability formation. At present, new type of perforating bullets are being developed with aperture and penetration of 1.5 fold respectively, but its high perforating energy make a thicker compacted zone around the penetrated channel, this result in a low conductivity.
This paper discusses about this problem, by applying new completion methods to reduce the formation damage in low permeable reservoir. First, the negative pressure perforation method is applied to reduce the stemming ; second, a compound high energy perforation method is applied to perform about 10cm length fissures which can penetrates the compacted zone around the channel thus increase the conductivity. Both of the two methods were applied combined on 166 tertiary infill wells in 2011, it increased a fluid productivity to 2.8t/d.m, it was 2.9 folds of the previous perforation. It effectively solved the problem of formation damage caused by deep penetration bullet to highly increase the fluid productivity in low permeable reservoir.
Daqing Oilfied is a typical continental deposited reservoir with multi-layers and serious heterogeneity. Sazhong area of Daqing Oilfied covers an area of 161.25 km2. Its OOIP is 10.5 bbls, its current recovery percent is 39.0% with a water cut of 87.25%. Although this oilfield is on its later stage of high water-cut, infill adjustment is still a kind of effective measure to improve recovery. It shows that the tertiary infill adjustment can improve its recovery by 3-4% according to both theoretical calculation and practice, but with the progress of infill adjustment, the formation factors of the target formations are becoming more and more adverse. The remaining oil distribution is more difficult to grasp. For the formations with a complex remaining oil distribution in space and in low permeability zones, the ever effective measures of completion technology used before is not adequate for all the requirements of infill adjustment wells. A new completion technology must be developed to meet the requirements of improving the general effect in extreme low permeability.
It is very difficult on the exploration of fracture-cavity carbonate reservoirs because of being restricted to the great heterogeneities and the complex situation of fracture-cavity system. In addition, the scale of target geologic body is much smaller than seismic resolution, it is very hard to find out several or several tens of meters caves which are 5000 meters below underground, even though detect its hydrocarbon characteristic. So the wells are always very hard to stay a high and steady productivity. The purpose of this research is through an accurate identification, particular description, veracious reserves calculation and reliable hydrocarbon detection for single fracture-cavity body to improve the reserve precision and drilling success ratio. At the same time to improve the percentage of high and steady productivity wells.