In Dec. 2006, China Geosteering Drilling System-1 (CGDS-1) was used in Well Qi 604-Well Lian H2Z in

 

Liaohe Oilfield. Well Qi 604-Well Lian H2Z are located in the block which is marginal oil sheet, its reservoir thickness is 2-3m, control degree of the oil layer is low, and attitude of the oil layer is changed badly. The working time of the instrument downhole was 30h. The results show that the data of MWD satisfy the operation requirement. After examination and verification of the geological engineers on site, it was considered that the MWD data curve basically reflected actual conditions of the oil layer. The application of CGDS-1 in the wells hugely increases predication accuracy of strata being waited to drill for engineering and geological technicians and enhances probability of penetration for oil layers further.

 

At the end of Jan. 2007, in Jidong Oilfield, field operation service in 3 horizontal wells were successfully finished, including Well LB-P8, Well L90¬P2 and Well L23-P8, with the accumulative footage of 2994. 5m and the accumulative working time of 860.5h. The results of field operation indicated that CGDS-1 meets the operation requirement of engineering, measurement parameters are exact and stable, and enhances probability of penetration for oil layers.

 

 

In Nov. 2008, the system was used in Well Huan

 

127-Well Lian H205 in Liaohe Oilfield.

 

(1) The geological and engineering parameters of MWD data are stable, upload transmission of data and

 

 

Test for downhole instrument of CGDS-1 is conducted after tripping out

 

CGDS-1 is tripped out of wellhead

 

 

 

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Near-bit Geosteering Drilling Technology

 

System test is conducted before operation

 

ground decodification are fast and exact. For CFDS, its interface is good and operation is convenient; operating life of motor is long, gauging nipple and motor of CAIMS are relatively independent and it is easy to maintain on site. CGDS-1 works steadily and bears relatively high dependability, which can satisfy the requirement for industrial application.

 

(2) The MWD result of geological parameters, such as near-bit azimuth resistivity, bit resistivity and azimuthal natural gamma, reflects the variation trend of reservoir that is verified by actual drilling

 

results. Compared with the present domestically used imported products, the CGDS-1 has obvious advantage of near-bit measurement and the important direction to enhance probability of penetration for oil and gas, pinpoint landing, etc.

 

In Feb. 2010, this technology was applied in Well Haoping 2 of Jianghan Oilfield. Well Haoping 2 is located in Haokou Block in Jianghan Oilfield, the block belongs to Haokou structural nose in Qianjiang Sag, and it has thin oil layer and complex geological structure belonging to ultrathin oil layer (minimum reservoir thickness is 0.66m), so it is difficult to operate. Since the measurement point of

 

CGDS can reflect the variation of formation lithology ontime, it makes Party A of the project cognize the formation more timely and distinctly, provides timely and exact stratigraphic information to geological staffs as well as timely visual evidence for decision of further engineering implementation, and enhances probability of penetration for drilling.