| China's volcanic reservoir of oil and gas exploration and development began in the 1970s, in the late 1990s by rapid development. At present, almost all of China's major oil and gas basins are discovered volcanic rocks and volcanic reservoir. China has built a large number of a certain size, certain reserves and output to the reservoir rocks consisting mainly of oil and gas fields. Comparison with other countries, our country has more development the Cenozoic volcanic reservoir of oil and gas basins in the reservoir.Songliao Basin volcanic research began in the 20th century early 1990s, in 1996 after entering the rapid development period. Because the exploration of the actual needs of Songliao Basin volcanic reservoir studies continuously deepened in recent years in reservoir rocks and volcanic reservoir studies achieved a major breakthrough. Earthquake rocks from the non-recognition to the volcanic gas reservoir geology - earthquakes have established a comprehensive description of the corresponding series of theoretical and technical methods series. Daqing Oilfield in the current volcanic reservoir rocks and reservoir forecasts and exploration success rate of the leading international standard of living in the area, in the relevant theoretical research also living in the forefront of domestic and foreign counterparts.Songliao Basin, the exploration of deep volcanic rocks in recent years has made significant discovery, the Daqing Oilfield in December 2005 in the Songliao Basin Xujiaweizi depression to the State Reserve Committee submitted a 1000×108m3 proved reserves of natural gas, volcanic rock that is the Songliao Deep Basin, the main reservoir. However, in the southern part of Songliao Basin in Changling faulted constantly reveals new wells, the volcanic region from Changling lithology, larger changes in the same rocks, reservoir rocks on the size and distribution of the need for further understanding.To this end, the author relies on key projects in petrochemicals, "the Songliao Basin in Changling faulted volcanic reservoir characteristics of carry out the basic unit from the volcanic rock (volcanic bodies) point of a new awareness of volcanic reservoir characteristics of the research work. Through the volcanic reservoir description of the earthquake, in the geological model of restraint under the volcanic geology of the reservoir - comprehensive description of earthquakes, volcanic reservoir for the Fine forecast to provide a working guideline for speeding up the discovery of natural gas and improve the efficiency of exploration Important theoretical and practical significance.This paper mainly focus on the integrated study of volcanic reservoir with cores, gravity and magnetic data, logging and seismic data in the Changling fault depression of the Songliao basin following the elemental principles of litholgoy and geophysics in order to find the effective methods to predict volcanic reservoir. According to the Songliao Basin in southern Changling faulted the delineation of gravity and magnetic data to the distribution of volcanic rocks, seismic data interpretation of the distribution of volcanic the use of statistical methods to establish geological rock phase of the relationship between the reservoir and volcanic agencies and the reservoir of the relationship The use of waveform classification identification of volcanic rock, using dip properties and coherent method of identification of the volcano; phase and the use of reservoir rocks and volcanoes, the quantitative relationship with the agency relationship between the quantitative reservoir of semi-quantitative evaluation of seismic attributes at the same time And the geological reservoir effective statistical relationship between the reservoir effective earthquake prediction, using seismic inversion forecast favorable reservoir of distribution; forecast by tectonic stress fracture to find favorable reservoir. Above geological and seismic methods of effective reservoir prediction results for effective integrated reservoir forecast.1. Gravity and magnetic methodThe lithology of basement has been classified based on the vertical secondary derivative anomaly and continuation of gravity and geomagnetism. According to the geomagnetic nature of volcanic rocks, the distribution of intermediate and basic volcanic rocks was sketched out based on the waveletes analysis.2. Logging methodAccording to the logging curve comparisons, the logging characteristics of volcanic rocks have the following principles. The rhyolite shows high natural gamma, electrical resistivity and low acoustic interval transit time (high velocity). The intermediate volcanic rocks, such as andesite, show high natural gamma and electrical resistivity and low acoustic interval transit time (high velocity). In general, from the basic volcanic rock to felsic volcanic rock, the radioactivity increases, the neutron response descends, the density decreases. Low electrical resistivity and high acoustic interval transit time are the unique characteristics of tuff.Element Capture Spectroscopy (ECS) data was employed to classify the volcanic rocks and to calculate the rock matrix parameters, that is, the ECS data was effective to recognize the lithology of volcanic rocks. The porosity of volcanic rocks can be recognized according to the density logging and nuclear magnetic resonance (NMR) logging as well as the rock matrix parameters calculated based on the ECS data. The effectivity of volcanic reservoir can be classified based on the porosity. The capillary pressure curve was calculated from the T2 distribution spectrum of NMR, then, the gas bedding was recognized based on the fluid saturation which was calculated based on the capillary pressure curve and the free water interface.3. Seismic reflection features analysis and recognition techniques The recognition resolution of seismic reflection to the deep volcanic reservoirs and the relationship among various wavelets were studied based on the wavelet forward of different frequency, thus, the recognition capability of current seismic data was deduced. The position and the spatial distribution of volcanic rocks were accurately sketched out with volcanic rocks orientated technique, for instance, the pre-stack depth migration technique and the unconventional section of seismic facies. 4. Integrated prediction of volcanic reservoir4.1 Prediction of development zones of volcanic cratersThe distribution and spatial extension of craters in the target area were recognized with coherence, dipping angle as well as various time slices of seismic data.4.2 the prediction of lateral distribution of volcanic faciesThe lateral distribution of volcanic facies was predicted with waveform clustering analysis method based on the distribution features in single well and the corresponding seismic reflection of volcanic rocks. The volcanic facies shows the following seismic reflection features. Volcanic vent facies: asymmetric acetabuliform, lenticular or wedge-shaped, low-middle frequency, weak-strong amplitude, bad continuity. Volcanic vent facies fingered with middle and lower subfacies of effusive facies in lateral. Explosive facies: sheet drape, slaty and wedge-shaped, and silllike drape, mid-low frequency and some is mid-high frequency, weak-mid amplitude and some is mid-strong amplitude, middle-well continuity and infrequent some is bad continuity. Effusive facies: wedge-shaped, sill-like drape, slaty and lenticular, mid-low frequency and some is mid-high frequency, mid-weak amplitude and some is mid-strong amplitude, middle-bad continuity and some is middle-well continuity. Extrusive facies: asymmetric bosslike, lenticular, slaty and wedge-shaped, mid-low frequency, mid-weak amplitude, bad continuity. Volcanogenitic sedimentary facies: silllike drape, mid-high frequency, strong amplitude, well continuity. Volcanic vent facies and its combination: asymmetric acetabuliform, lenticular or wedge-shaped, low-middle frequency, weak-strong amplitude, bad continuity. Volcanic vent facies fingered with middle and lower subfacies of effusive facies in lateral.Explosive facies and is combination: sheet drape, slaty and wedge-shaped, and silllike drape, mid-low frequency and some is mid-high frequency, weak-mid amplitude and some is mid-strong amplitude, middle-well continuity and infrequent some is bad continuity.Effusive facies and is combination: wedge-shaped, silllike drape, slaty and lenticular, mid-low frequency and some is mid-high frequency, mid-weak amplitude and some is mid-strong amplitude, middle-bad continuity and some is middle-well continuity.Extrusive facies and is combination: asymmetric bosslike, lenticular, slaty and wedge-shaped, mid-low frequency, mid-weak amplitude, bad continuity. Volcanogenitic sedimentary facies and is combination: silllike drape, mid-high frequency, strong amplitude, well continuity.4.3 Integrated prediction of volcanic reservoirThe wave impedance inversion method was used here to predict volcanic reservoir. The tectonic evolution history as well as the development strata, occurrences and nature of fissures was modelled based on the regional tectonic stress field analysis. The gas saturation was analyzed with instantaneous wavelet technique.The distribution of volcanic reservoir and the volcanic gas pool were studied with the methods mentioned before. The volcanic reservoir was preferable to develop in the explosive facies and the effusive facies near the crater, the local relative tectonic highs and close to the fault, the development of volcanic reservoir was controlled by the volcanic edifices. The structure -lithology gas pools are dominating in the target area. The most advantageous position for drilling situates in the local tectonic highs of fault developed zones, especially the crater area. The current research results indicate the volcanic rocks of Yingcheng formation (K1yc) in Yaoyingtai region have the best exploration and development potential and.in Dongling region have better potential.
|
PDF Full Text Request