This paper srggests removing the effects of regional gravitational fields, and the gravitational fields arising from density interfaces and shallow interference by making use of high accuracy gravity data together with known geological and seismic information so as to yield the residiual gravity anomalies.

As a result, the application of the method in recognizing weak anomalies of high accuracy gravity survey and determining the accurate position of buried hill in oil-bearing sedimcntary basin has brought forth sat isfactory results.

Based on the analysis of well drilling and physical property,using the high accuracy gravity and magnetic survey,the field modelling suvery depth,the seismic data,this paper makes a synthetic study of the Paleozoic Erathem interior lithology,lithofacies and their distribution rule.

Oil gravity survey in China began in 1945, then rather flourished in 1950s.By the end of 1950s,the petroleum industry had 36 gravity survey crews; however, at the beginning of 1960s,the gravity survey crews began to decrease with years. By the mid 1970s, the crew number stopped dropping and staned increasing because gravity survey scored quite good geological effect in exploring buried hills and because gravity survey must be done urgently in many medium-sized and smallsized basins....

Oil gravity survey in China began in 1945, then rather flourished in 1950s.By the end of 1950s,the petroleum industry had 36 gravity survey crews; however, at the beginning of 1960s,the gravity survey crews began to decrease with years. By the mid 1970s, the crew number stopped dropping and staned increasing because gravity survey scored quite good geological effect in exploring buried hills and because gravity survey must be done urgently in many medium-sized and smallsized basins. The practice shows that gravity survey is a quite good exploration method for researching into areal geological structure be- cause of its merits: low cost, fast operation and nice effect. Furthermore, gravity survey also brings good result in researching into the local geological structure, particularly the buried hills. Looking forward to the future,we have the following works to do: · Areal exploration of new basins; · New comprehensive study of old basins using not only new and old gravimetric data but also other geophysical and drilling data; · Mountainous-district gravity survey in combination with seismic exploration, and the improvement of both its accuracy and its effect; · High-accuracy gravity survey which mainly focuses its attention on buried hill; · Scientific researches on borehole gravity survey.aerogravity survey and the new data processing technique.

This paper srggests removing the effects of regional gravitational fields, and the gravitational fields arising from density interfaces and shallow interference by making use of high accuracy gravity data together with known geological and seismic information so as to yield the residiual gravity anomalies. Constrained by drilling data, inversion for residual density distribution is then performed to find out where fractures densely flock (i. e. the zone in which oil/gas potentialy accumulates) in...

This paper srggests removing the effects of regional gravitational fields, and the gravitational fields arising from density interfaces and shallow interference by making use of high accuracy gravity data together with known geological and seismic information so as to yield the residiual gravity anomalies. Constrained by drilling data, inversion for residual density distribution is then performed to find out where fractures densely flock (i. e. the zone in which oil/gas potentialy accumulates) in reservoir rocks. While confirmed to be effective via some theoretical model examples, the method was also applied to the real data from DaZuo area of Sichuan Province in delineating the lithology and fracture traps of this area. The results from the inversion are further verified via the comparison with known well-log, geological and other geophysical data. It is concluded that the method proposed in the paper is promising to be an useful tool in locating fracture type reservoirs in marine carbonate areas.

In this papcr, we make use of the orthogonal transformation method to transform the coefficient matrix of trcnd surface analysis to a diagonal matrix so as to avoid solving ill-conditioned system of cquations and improve the precision of solution . Meanwhile , the normal equations are transformed to a first-ordcr system of cquations which is very casy to solve,thcrefore, the solving process is sped up. Furthcr, the order-fixed trend surface analysis which is responsible for false anomaly is replaeed by sliding...

In this papcr, we make use of the orthogonal transformation method to transform the coefficient matrix of trcnd surface analysis to a diagonal matrix so as to avoid solving ill-conditioned system of cquations and improve the precision of solution . Meanwhile , the normal equations are transformed to a first-ordcr system of cquations which is very casy to solve,thcrefore, the solving process is sped up. Furthcr, the order-fixed trend surface analysis which is responsible for false anomaly is replaeed by sliding window and order-variant trend surface analysis. As a result, the application of the method in recognizing weak anomalies of high accuracy gravity survey and determining the accurate position of buried hill in oil-bearing sedimcntary basin has brought forth sat isfactory results.